From 22d8ef540ea35ccbab955cabd6281e5b130af508 Mon Sep 17 00:00:00 2001
From: Haily Nguyen <haily.ng@uber.com>
Date: Thu, 12 Sep 2024 12:50:45 -0700
Subject: [PATCH] make rewrite default for single-file mode and update ALL
 generate test cases

---
 _examples/type-system-extension/gqlgen.yml    |   3 -
 codegen/testserver/followschema/resolver.go   | 213 +++++++++---------
 .../testserver/nullabledirectives/gqlgen.yml  |   5 +-
 codegen/testserver/singlefile/resolver.go     | 213 +++++++++---------
 integration/server/gqlgen.yml                 |   3 -
 plugin/resolvergen/resolver.go                |  26 ++-
 plugin/resolvergen/resolver.gotpl             |   2 +
 .../testdata/singlefile/out/resolver.go       |   7 +-
 8 files changed, 241 insertions(+), 231 deletions(-)

diff --git a/_examples/type-system-extension/gqlgen.yml b/_examples/type-system-extension/gqlgen.yml
index bc7a31dba0..eba540c1f8 100644
--- a/_examples/type-system-extension/gqlgen.yml
+++ b/_examples/type-system-extension/gqlgen.yml
@@ -10,6 +10,3 @@ exec:
   filename: generated.go
 model:
   filename: models_gen.go
-resolver:
-  filename: resolver.go
-  type: Resolver
diff --git a/codegen/testserver/followschema/resolver.go b/codegen/testserver/followschema/resolver.go
index 94bd8816ca..ce5ce96966 100644
--- a/codegen/testserver/followschema/resolver.go
+++ b/codegen/testserver/followschema/resolver.go
@@ -1,9 +1,10 @@
 package followschema
 
-// THIS CODE IS A STARTING POINT ONLY. IT WILL NOT BE UPDATED WITH SCHEMA CHANGES.
+// THIS CODE WILL BE UPDATED WITH SCHEMA CHANGES. PREVIOUS IMPLEMENTATION FOR SCHEMA CHANGES WILL BE KEPT IN THE COMMENT SECTION. IMPLEMENTATION FOR UNCHANGED SCHEMA WILL BE KEPT.
 
 import (
 	"context"
+	"fmt"
 
 	introspection1 "github.com/99designs/gqlgen/codegen/testserver/followschema/introspection"
 	invalid_packagename "github.com/99designs/gqlgen/codegen/testserver/followschema/invalid-packagename"
@@ -14,527 +15,527 @@ type Resolver struct{}
 
 // ID is the resolver for the id field.
 func (r *backedByInterfaceResolver) ID(ctx context.Context, obj BackedByInterface) (string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: ID - id"))
 }
 
 // Values is the resolver for the values field.
 func (r *deferModelResolver) Values(ctx context.Context, obj *DeferModel) ([]string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Values - values"))
 }
 
 // A is the resolver for the a field.
 func (r *errorsResolver) A(ctx context.Context, obj *Errors) (*Error, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: A - a"))
 }
 
 // B is the resolver for the b field.
 func (r *errorsResolver) B(ctx context.Context, obj *Errors) (*Error, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: B - b"))
 }
 
 // C is the resolver for the c field.
 func (r *errorsResolver) C(ctx context.Context, obj *Errors) (*Error, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: C - c"))
 }
 
 // D is the resolver for the d field.
 func (r *errorsResolver) D(ctx context.Context, obj *Errors) (*Error, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: D - d"))
 }
 
 // E is the resolver for the e field.
 func (r *errorsResolver) E(ctx context.Context, obj *Errors) (*Error, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: E - e"))
 }
 
 // Field is the resolver for the field field.
 func (r *forcedResolverResolver) Field(ctx context.Context, obj *ForcedResolver) (*Circle, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Field - field"))
 }
 
 // ResolverField is the resolver for the resolverField field.
 func (r *modelMethodsResolver) ResolverField(ctx context.Context, obj *ModelMethods) (bool, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: ResolverField - resolverField"))
 }
 
 // DefaultInput is the resolver for the defaultInput field.
 func (r *mutationResolver) DefaultInput(ctx context.Context, input DefaultInput) (*DefaultParametersMirror, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: DefaultInput - defaultInput"))
 }
 
 // OverrideValueViaInput is the resolver for the overrideValueViaInput field.
 func (r *mutationResolver) OverrideValueViaInput(ctx context.Context, input FieldsOrderInput) (*FieldsOrderPayload, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: OverrideValueViaInput - overrideValueViaInput"))
 }
 
 // UpdateSomething is the resolver for the updateSomething field.
 func (r *mutationResolver) UpdateSomething(ctx context.Context, input SpecialInput) (string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: UpdateSomething - updateSomething"))
 }
 
 // UpdatePtrToPtr is the resolver for the updatePtrToPtr field.
 func (r *mutationResolver) UpdatePtrToPtr(ctx context.Context, input UpdatePtrToPtrOuter) (*PtrToPtrOuter, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: UpdatePtrToPtr - updatePtrToPtr"))
 }
 
 // OldFoo is the resolver for the oldFoo field.
 func (r *overlappingFieldsResolver) OldFoo(ctx context.Context, obj *OverlappingFields) (int, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: OldFoo - oldFoo"))
 }
 
 // FieldScalarMarshal is the resolver for the fieldScalarMarshal field.
 func (r *panicsResolver) FieldScalarMarshal(ctx context.Context, obj *Panics) ([]MarshalPanic, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: FieldScalarMarshal - fieldScalarMarshal"))
 }
 
 // ArgUnmarshal is the resolver for the argUnmarshal field.
 func (r *panicsResolver) ArgUnmarshal(ctx context.Context, obj *Panics, u []MarshalPanic) (bool, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: ArgUnmarshal - argUnmarshal"))
 }
 
 // Friends is the resolver for the friends field.
 func (r *petResolver) Friends(ctx context.Context, obj *Pet, limit *int) ([]*Pet, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Friends - friends"))
 }
 
 // Value is the resolver for the value field.
 func (r *primitiveResolver) Value(ctx context.Context, obj *Primitive) (int, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Value - value"))
 }
 
 // Value is the resolver for the value field.
 func (r *primitiveStringResolver) Value(ctx context.Context, obj *PrimitiveString) (string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Value - value"))
 }
 
 // Len is the resolver for the len field.
 func (r *primitiveStringResolver) Len(ctx context.Context, obj *PrimitiveString) (int, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Len - len"))
 }
 
 // InvalidIdentifier is the resolver for the invalidIdentifier field.
 func (r *queryResolver) InvalidIdentifier(ctx context.Context) (*invalid_packagename.InvalidIdentifier, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: InvalidIdentifier - invalidIdentifier"))
 }
 
 // Collision is the resolver for the collision field.
 func (r *queryResolver) Collision(ctx context.Context) (*introspection1.It, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Collision - collision"))
 }
 
 // MapInput is the resolver for the mapInput field.
 func (r *queryResolver) MapInput(ctx context.Context, input map[string]interface{}) (*bool, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: MapInput - mapInput"))
 }
 
 // Recursive is the resolver for the recursive field.
 func (r *queryResolver) Recursive(ctx context.Context, input *RecursiveInputSlice) (*bool, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Recursive - recursive"))
 }
 
 // NestedInputs is the resolver for the nestedInputs field.
 func (r *queryResolver) NestedInputs(ctx context.Context, input [][]*OuterInput) (*bool, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: NestedInputs - nestedInputs"))
 }
 
 // NestedOutputs is the resolver for the nestedOutputs field.
 func (r *queryResolver) NestedOutputs(ctx context.Context) ([][]*OuterObject, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: NestedOutputs - nestedOutputs"))
 }
 
 // ModelMethods is the resolver for the modelMethods field.
 func (r *queryResolver) ModelMethods(ctx context.Context) (*ModelMethods, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: ModelMethods - modelMethods"))
 }
 
 // User is the resolver for the user field.
 func (r *queryResolver) User(ctx context.Context, id int) (*User, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: User - user"))
 }
 
 // NullableArg is the resolver for the nullableArg field.
 func (r *queryResolver) NullableArg(ctx context.Context, arg *int) (*string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: NullableArg - nullableArg"))
 }
 
 // InputSlice is the resolver for the inputSlice field.
 func (r *queryResolver) InputSlice(ctx context.Context, arg []string) (bool, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: InputSlice - inputSlice"))
 }
 
 // InputNullableSlice is the resolver for the inputNullableSlice field.
 func (r *queryResolver) InputNullableSlice(ctx context.Context, arg []string) (bool, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: InputNullableSlice - inputNullableSlice"))
 }
 
 // InputOmittable is the resolver for the inputOmittable field.
 func (r *queryResolver) InputOmittable(ctx context.Context, arg OmittableInput) (string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: InputOmittable - inputOmittable"))
 }
 
 // ShapeUnion is the resolver for the shapeUnion field.
 func (r *queryResolver) ShapeUnion(ctx context.Context) (ShapeUnion, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: ShapeUnion - shapeUnion"))
 }
 
 // Autobind is the resolver for the autobind field.
 func (r *queryResolver) Autobind(ctx context.Context) (*Autobind, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Autobind - autobind"))
 }
 
 // DeprecatedField is the resolver for the deprecatedField field.
 func (r *queryResolver) DeprecatedField(ctx context.Context) (string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: DeprecatedField - deprecatedField"))
 }
 
 // Overlapping is the resolver for the overlapping field.
 func (r *queryResolver) Overlapping(ctx context.Context) (*OverlappingFields, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Overlapping - overlapping"))
 }
 
 // DefaultParameters is the resolver for the defaultParameters field.
 func (r *queryResolver) DefaultParameters(ctx context.Context, falsyBoolean *bool, truthyBoolean *bool) (*DefaultParametersMirror, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: DefaultParameters - defaultParameters"))
 }
 
 // DeferCase1 is the resolver for the deferCase1 field.
 func (r *queryResolver) DeferCase1(ctx context.Context) (*DeferModel, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: DeferCase1 - deferCase1"))
 }
 
 // DeferCase2 is the resolver for the deferCase2 field.
 func (r *queryResolver) DeferCase2(ctx context.Context) ([]*DeferModel, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: DeferCase2 - deferCase2"))
 }
 
 // DirectiveArg is the resolver for the directiveArg field.
 func (r *queryResolver) DirectiveArg(ctx context.Context, arg string) (*string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: DirectiveArg - directiveArg"))
 }
 
 // DirectiveNullableArg is the resolver for the directiveNullableArg field.
 func (r *queryResolver) DirectiveNullableArg(ctx context.Context, arg *int, arg2 *int, arg3 *string) (*string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: DirectiveNullableArg - directiveNullableArg"))
 }
 
 // DirectiveSingleNullableArg is the resolver for the directiveSingleNullableArg field.
 func (r *queryResolver) DirectiveSingleNullableArg(ctx context.Context, arg1 *string) (*string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: DirectiveSingleNullableArg - directiveSingleNullableArg"))
 }
 
 // DirectiveInputNullable is the resolver for the directiveInputNullable field.
 func (r *queryResolver) DirectiveInputNullable(ctx context.Context, arg *InputDirectives) (*string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: DirectiveInputNullable - directiveInputNullable"))
 }
 
 // DirectiveInput is the resolver for the directiveInput field.
 func (r *queryResolver) DirectiveInput(ctx context.Context, arg InputDirectives) (*string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: DirectiveInput - directiveInput"))
 }
 
 // DirectiveInputType is the resolver for the directiveInputType field.
 func (r *queryResolver) DirectiveInputType(ctx context.Context, arg InnerInput) (*string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: DirectiveInputType - directiveInputType"))
 }
 
 // DirectiveObject is the resolver for the directiveObject field.
 func (r *queryResolver) DirectiveObject(ctx context.Context) (*ObjectDirectives, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: DirectiveObject - directiveObject"))
 }
 
 // DirectiveObjectWithCustomGoModel is the resolver for the directiveObjectWithCustomGoModel field.
 func (r *queryResolver) DirectiveObjectWithCustomGoModel(ctx context.Context) (*ObjectDirectivesWithCustomGoModel, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: DirectiveObjectWithCustomGoModel - directiveObjectWithCustomGoModel"))
 }
 
 // DirectiveFieldDef is the resolver for the directiveFieldDef field.
 func (r *queryResolver) DirectiveFieldDef(ctx context.Context, ret string) (string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: DirectiveFieldDef - directiveFieldDef"))
 }
 
 // DirectiveField is the resolver for the directiveField field.
 func (r *queryResolver) DirectiveField(ctx context.Context) (*string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: DirectiveField - directiveField"))
 }
 
 // DirectiveDouble is the resolver for the directiveDouble field.
 func (r *queryResolver) DirectiveDouble(ctx context.Context) (*string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: DirectiveDouble - directiveDouble"))
 }
 
 // DirectiveUnimplemented is the resolver for the directiveUnimplemented field.
 func (r *queryResolver) DirectiveUnimplemented(ctx context.Context) (*string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: DirectiveUnimplemented - directiveUnimplemented"))
 }
 
 // DirectiveConcurrent is the resolver for the directiveConcurrent field.
 func (r *queryResolver) DirectiveConcurrent(ctx context.Context) ([]*ObjectDirectivesConcurrent, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: DirectiveConcurrent - directiveConcurrent"))
 }
 
 // EmbeddedCase1 is the resolver for the embeddedCase1 field.
 func (r *queryResolver) EmbeddedCase1(ctx context.Context) (*EmbeddedCase1, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: EmbeddedCase1 - embeddedCase1"))
 }
 
 // EmbeddedCase2 is the resolver for the embeddedCase2 field.
 func (r *queryResolver) EmbeddedCase2(ctx context.Context) (*EmbeddedCase2, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: EmbeddedCase2 - embeddedCase2"))
 }
 
 // EmbeddedCase3 is the resolver for the embeddedCase3 field.
 func (r *queryResolver) EmbeddedCase3(ctx context.Context) (*EmbeddedCase3, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: EmbeddedCase3 - embeddedCase3"))
 }
 
 // EnumInInput is the resolver for the enumInInput field.
 func (r *queryResolver) EnumInInput(ctx context.Context, input *InputWithEnumValue) (EnumTest, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: EnumInInput - enumInInput"))
 }
 
 // Shapes is the resolver for the shapes field.
 func (r *queryResolver) Shapes(ctx context.Context) ([]Shape, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Shapes - shapes"))
 }
 
 // NoShape is the resolver for the noShape field.
 func (r *queryResolver) NoShape(ctx context.Context) (Shape, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: NoShape - noShape"))
 }
 
 // Node is the resolver for the node field.
 func (r *queryResolver) Node(ctx context.Context) (Node, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Node - node"))
 }
 
 // NoShapeTypedNil is the resolver for the noShapeTypedNil field.
 func (r *queryResolver) NoShapeTypedNil(ctx context.Context) (Shape, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: NoShapeTypedNil - noShapeTypedNil"))
 }
 
 // Animal is the resolver for the animal field.
 func (r *queryResolver) Animal(ctx context.Context) (Animal, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Animal - animal"))
 }
 
 // NotAnInterface is the resolver for the notAnInterface field.
 func (r *queryResolver) NotAnInterface(ctx context.Context) (BackedByInterface, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: NotAnInterface - notAnInterface"))
 }
 
 // Dog is the resolver for the dog field.
 func (r *queryResolver) Dog(ctx context.Context) (*Dog, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Dog - dog"))
 }
 
 // Issue896a is the resolver for the issue896a field.
 func (r *queryResolver) Issue896a(ctx context.Context) ([]*CheckIssue896, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Issue896a - issue896a"))
 }
 
 // MapStringInterface is the resolver for the mapStringInterface field.
 func (r *queryResolver) MapStringInterface(ctx context.Context, in map[string]interface{}) (map[string]interface{}, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: MapStringInterface - mapStringInterface"))
 }
 
 // MapNestedStringInterface is the resolver for the mapNestedStringInterface field.
 func (r *queryResolver) MapNestedStringInterface(ctx context.Context, in *NestedMapInput) (map[string]interface{}, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: MapNestedStringInterface - mapNestedStringInterface"))
 }
 
 // ErrorBubble is the resolver for the errorBubble field.
 func (r *queryResolver) ErrorBubble(ctx context.Context) (*Error, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: ErrorBubble - errorBubble"))
 }
 
 // ErrorBubbleList is the resolver for the errorBubbleList field.
 func (r *queryResolver) ErrorBubbleList(ctx context.Context) ([]*Error, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: ErrorBubbleList - errorBubbleList"))
 }
 
 // ErrorList is the resolver for the errorList field.
 func (r *queryResolver) ErrorList(ctx context.Context) ([]*Error, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: ErrorList - errorList"))
 }
 
 // Errors is the resolver for the errors field.
 func (r *queryResolver) Errors(ctx context.Context) (*Errors, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Errors - errors"))
 }
 
 // Valid is the resolver for the valid field.
 func (r *queryResolver) Valid(ctx context.Context) (string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Valid - valid"))
 }
 
 // Invalid is the resolver for the invalid field.
 func (r *queryResolver) Invalid(ctx context.Context) (string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Invalid - invalid"))
 }
 
 // Panics is the resolver for the panics field.
 func (r *queryResolver) Panics(ctx context.Context) (*Panics, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Panics - panics"))
 }
 
 // PrimitiveObject is the resolver for the primitiveObject field.
 func (r *queryResolver) PrimitiveObject(ctx context.Context) ([]Primitive, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: PrimitiveObject - primitiveObject"))
 }
 
 // PrimitiveStringObject is the resolver for the primitiveStringObject field.
 func (r *queryResolver) PrimitiveStringObject(ctx context.Context) ([]PrimitiveString, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: PrimitiveStringObject - primitiveStringObject"))
 }
 
 // PtrToAnyContainer is the resolver for the ptrToAnyContainer field.
 func (r *queryResolver) PtrToAnyContainer(ctx context.Context) (*PtrToAnyContainer, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: PtrToAnyContainer - ptrToAnyContainer"))
 }
 
 // PtrToSliceContainer is the resolver for the ptrToSliceContainer field.
 func (r *queryResolver) PtrToSliceContainer(ctx context.Context) (*PtrToSliceContainer, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: PtrToSliceContainer - ptrToSliceContainer"))
 }
 
 // Infinity is the resolver for the infinity field.
 func (r *queryResolver) Infinity(ctx context.Context) (float64, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Infinity - infinity"))
 }
 
 // StringFromContextInterface is the resolver for the stringFromContextInterface field.
 func (r *queryResolver) StringFromContextInterface(ctx context.Context) (*StringFromContextInterface, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: StringFromContextInterface - stringFromContextInterface"))
 }
 
 // StringFromContextFunction is the resolver for the stringFromContextFunction field.
 func (r *queryResolver) StringFromContextFunction(ctx context.Context) (string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: StringFromContextFunction - stringFromContextFunction"))
 }
 
 // DefaultScalar is the resolver for the defaultScalar field.
 func (r *queryResolver) DefaultScalar(ctx context.Context, arg string) (string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: DefaultScalar - defaultScalar"))
 }
 
 // Slices is the resolver for the slices field.
 func (r *queryResolver) Slices(ctx context.Context) (*Slices, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Slices - slices"))
 }
 
 // ScalarSlice is the resolver for the scalarSlice field.
 func (r *queryResolver) ScalarSlice(ctx context.Context) ([]byte, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: ScalarSlice - scalarSlice"))
 }
 
 // Fallback is the resolver for the fallback field.
 func (r *queryResolver) Fallback(ctx context.Context, arg FallbackToStringEncoding) (FallbackToStringEncoding, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Fallback - fallback"))
 }
 
 // OptionalUnion is the resolver for the optionalUnion field.
 func (r *queryResolver) OptionalUnion(ctx context.Context) (TestUnion, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: OptionalUnion - optionalUnion"))
 }
 
 // VOkCaseValue is the resolver for the vOkCaseValue field.
 func (r *queryResolver) VOkCaseValue(ctx context.Context) (*VOkCaseValue, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: VOkCaseValue - vOkCaseValue"))
 }
 
 // VOkCaseNil is the resolver for the vOkCaseNil field.
 func (r *queryResolver) VOkCaseNil(ctx context.Context) (*VOkCaseNil, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: VOkCaseNil - vOkCaseNil"))
 }
 
 // ValidType is the resolver for the validType field.
 func (r *queryResolver) ValidType(ctx context.Context) (*ValidType, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: ValidType - validType"))
 }
 
 // VariadicModel is the resolver for the variadicModel field.
 func (r *queryResolver) VariadicModel(ctx context.Context) (*VariadicModel, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: VariadicModel - variadicModel"))
 }
 
 // WrappedStruct is the resolver for the wrappedStruct field.
 func (r *queryResolver) WrappedStruct(ctx context.Context) (*WrappedStruct, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: WrappedStruct - wrappedStruct"))
 }
 
 // WrappedScalar is the resolver for the wrappedScalar field.
 func (r *queryResolver) WrappedScalar(ctx context.Context) (otherpkg.Scalar, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: WrappedScalar - wrappedScalar"))
 }
 
 // WrappedMap is the resolver for the wrappedMap field.
 func (r *queryResolver) WrappedMap(ctx context.Context) (WrappedMap, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: WrappedMap - wrappedMap"))
 }
 
 // WrappedSlice is the resolver for the wrappedSlice field.
 func (r *queryResolver) WrappedSlice(ctx context.Context) (WrappedSlice, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: WrappedSlice - wrappedSlice"))
 }
 
 // Updated is the resolver for the updated field.
 func (r *subscriptionResolver) Updated(ctx context.Context) (<-chan string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Updated - updated"))
 }
 
 // InitPayload is the resolver for the initPayload field.
 func (r *subscriptionResolver) InitPayload(ctx context.Context) (<-chan string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: InitPayload - initPayload"))
 }
 
 // DirectiveArg is the resolver for the directiveArg field.
 func (r *subscriptionResolver) DirectiveArg(ctx context.Context, arg string) (<-chan *string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: DirectiveArg - directiveArg"))
 }
 
 // DirectiveNullableArg is the resolver for the directiveNullableArg field.
 func (r *subscriptionResolver) DirectiveNullableArg(ctx context.Context, arg *int, arg2 *int, arg3 *string) (<-chan *string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: DirectiveNullableArg - directiveNullableArg"))
 }
 
 // DirectiveDouble is the resolver for the directiveDouble field.
 func (r *subscriptionResolver) DirectiveDouble(ctx context.Context) (<-chan *string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: DirectiveDouble - directiveDouble"))
 }
 
 // DirectiveUnimplemented is the resolver for the directiveUnimplemented field.
 func (r *subscriptionResolver) DirectiveUnimplemented(ctx context.Context) (<-chan *string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: DirectiveUnimplemented - directiveUnimplemented"))
 }
 
 // Issue896b is the resolver for the issue896b field.
 func (r *subscriptionResolver) Issue896b(ctx context.Context) (<-chan []*CheckIssue896, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Issue896b - issue896b"))
 }
 
 // ErrorRequired is the resolver for the errorRequired field.
 func (r *subscriptionResolver) ErrorRequired(ctx context.Context) (<-chan *Error, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: ErrorRequired - errorRequired"))
 }
 
 // Friends is the resolver for the friends field.
 func (r *userResolver) Friends(ctx context.Context, obj *User) ([]*User, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Friends - friends"))
 }
 
 // Pets is the resolver for the pets field.
 func (r *userResolver) Pets(ctx context.Context, obj *User, limit *int) ([]*Pet, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Pets - pets"))
 }
 
 // Get is the resolver for the get field.
 func (r *wrappedMapResolver) Get(ctx context.Context, obj WrappedMap, key string) (string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Get - get"))
 }
 
 // Get is the resolver for the get field.
 func (r *wrappedSliceResolver) Get(ctx context.Context, obj WrappedSlice, idx int) (string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Get - get"))
 }
 
 // BackedByInterface returns BackedByInterfaceResolver implementation.
diff --git a/codegen/testserver/nullabledirectives/gqlgen.yml b/codegen/testserver/nullabledirectives/gqlgen.yml
index 657e9d0412..0090b822b2 100644
--- a/codegen/testserver/nullabledirectives/gqlgen.yml
+++ b/codegen/testserver/nullabledirectives/gqlgen.yml
@@ -8,9 +8,6 @@ exec:
 model:
   filename: generated/models/models-gen.go
   package: models
-resolver:
-  filename: generated/resolvers/resolver.go
-  package: resolver
-  type: Resolver
+
 
 call_argument_directives_with_null: true
diff --git a/codegen/testserver/singlefile/resolver.go b/codegen/testserver/singlefile/resolver.go
index 89a37561ab..4a6263f97b 100644
--- a/codegen/testserver/singlefile/resolver.go
+++ b/codegen/testserver/singlefile/resolver.go
@@ -1,9 +1,10 @@
 package singlefile
 
-// THIS CODE IS A STARTING POINT ONLY. IT WILL NOT BE UPDATED WITH SCHEMA CHANGES.
+// THIS CODE WILL BE UPDATED WITH SCHEMA CHANGES. PREVIOUS IMPLEMENTATION FOR SCHEMA CHANGES WILL BE KEPT IN THE COMMENT SECTION. IMPLEMENTATION FOR UNCHANGED SCHEMA WILL BE KEPT.
 
 import (
 	"context"
+	"fmt"
 
 	introspection1 "github.com/99designs/gqlgen/codegen/testserver/singlefile/introspection"
 	invalid_packagename "github.com/99designs/gqlgen/codegen/testserver/singlefile/invalid-packagename"
@@ -14,527 +15,527 @@ type Resolver struct{}
 
 // ID is the resolver for the id field.
 func (r *backedByInterfaceResolver) ID(ctx context.Context, obj BackedByInterface) (string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: ID - id"))
 }
 
 // Values is the resolver for the values field.
 func (r *deferModelResolver) Values(ctx context.Context, obj *DeferModel) ([]string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Values - values"))
 }
 
 // A is the resolver for the a field.
 func (r *errorsResolver) A(ctx context.Context, obj *Errors) (*Error, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: A - a"))
 }
 
 // B is the resolver for the b field.
 func (r *errorsResolver) B(ctx context.Context, obj *Errors) (*Error, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: B - b"))
 }
 
 // C is the resolver for the c field.
 func (r *errorsResolver) C(ctx context.Context, obj *Errors) (*Error, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: C - c"))
 }
 
 // D is the resolver for the d field.
 func (r *errorsResolver) D(ctx context.Context, obj *Errors) (*Error, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: D - d"))
 }
 
 // E is the resolver for the e field.
 func (r *errorsResolver) E(ctx context.Context, obj *Errors) (*Error, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: E - e"))
 }
 
 // Field is the resolver for the field field.
 func (r *forcedResolverResolver) Field(ctx context.Context, obj *ForcedResolver) (*Circle, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Field - field"))
 }
 
 // ResolverField is the resolver for the resolverField field.
 func (r *modelMethodsResolver) ResolverField(ctx context.Context, obj *ModelMethods) (bool, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: ResolverField - resolverField"))
 }
 
 // DefaultInput is the resolver for the defaultInput field.
 func (r *mutationResolver) DefaultInput(ctx context.Context, input DefaultInput) (*DefaultParametersMirror, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: DefaultInput - defaultInput"))
 }
 
 // OverrideValueViaInput is the resolver for the overrideValueViaInput field.
 func (r *mutationResolver) OverrideValueViaInput(ctx context.Context, input FieldsOrderInput) (*FieldsOrderPayload, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: OverrideValueViaInput - overrideValueViaInput"))
 }
 
 // UpdateSomething is the resolver for the updateSomething field.
 func (r *mutationResolver) UpdateSomething(ctx context.Context, input SpecialInput) (string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: UpdateSomething - updateSomething"))
 }
 
 // UpdatePtrToPtr is the resolver for the updatePtrToPtr field.
 func (r *mutationResolver) UpdatePtrToPtr(ctx context.Context, input UpdatePtrToPtrOuter) (*PtrToPtrOuter, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: UpdatePtrToPtr - updatePtrToPtr"))
 }
 
 // OldFoo is the resolver for the oldFoo field.
 func (r *overlappingFieldsResolver) OldFoo(ctx context.Context, obj *OverlappingFields) (int, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: OldFoo - oldFoo"))
 }
 
 // FieldScalarMarshal is the resolver for the fieldScalarMarshal field.
 func (r *panicsResolver) FieldScalarMarshal(ctx context.Context, obj *Panics) ([]MarshalPanic, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: FieldScalarMarshal - fieldScalarMarshal"))
 }
 
 // ArgUnmarshal is the resolver for the argUnmarshal field.
 func (r *panicsResolver) ArgUnmarshal(ctx context.Context, obj *Panics, u []MarshalPanic) (bool, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: ArgUnmarshal - argUnmarshal"))
 }
 
 // Friends is the resolver for the friends field.
 func (r *petResolver) Friends(ctx context.Context, obj *Pet, limit *int) ([]*Pet, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Friends - friends"))
 }
 
 // Value is the resolver for the value field.
 func (r *primitiveResolver) Value(ctx context.Context, obj *Primitive) (int, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Value - value"))
 }
 
 // Value is the resolver for the value field.
 func (r *primitiveStringResolver) Value(ctx context.Context, obj *PrimitiveString) (string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Value - value"))
 }
 
 // Len is the resolver for the len field.
 func (r *primitiveStringResolver) Len(ctx context.Context, obj *PrimitiveString) (int, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Len - len"))
 }
 
 // InvalidIdentifier is the resolver for the invalidIdentifier field.
 func (r *queryResolver) InvalidIdentifier(ctx context.Context) (*invalid_packagename.InvalidIdentifier, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: InvalidIdentifier - invalidIdentifier"))
 }
 
 // Collision is the resolver for the collision field.
 func (r *queryResolver) Collision(ctx context.Context) (*introspection1.It, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Collision - collision"))
 }
 
 // MapInput is the resolver for the mapInput field.
 func (r *queryResolver) MapInput(ctx context.Context, input map[string]interface{}) (*bool, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: MapInput - mapInput"))
 }
 
 // Recursive is the resolver for the recursive field.
 func (r *queryResolver) Recursive(ctx context.Context, input *RecursiveInputSlice) (*bool, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Recursive - recursive"))
 }
 
 // NestedInputs is the resolver for the nestedInputs field.
 func (r *queryResolver) NestedInputs(ctx context.Context, input [][]*OuterInput) (*bool, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: NestedInputs - nestedInputs"))
 }
 
 // NestedOutputs is the resolver for the nestedOutputs field.
 func (r *queryResolver) NestedOutputs(ctx context.Context) ([][]*OuterObject, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: NestedOutputs - nestedOutputs"))
 }
 
 // ModelMethods is the resolver for the modelMethods field.
 func (r *queryResolver) ModelMethods(ctx context.Context) (*ModelMethods, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: ModelMethods - modelMethods"))
 }
 
 // User is the resolver for the user field.
 func (r *queryResolver) User(ctx context.Context, id int) (*User, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: User - user"))
 }
 
 // NullableArg is the resolver for the nullableArg field.
 func (r *queryResolver) NullableArg(ctx context.Context, arg *int) (*string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: NullableArg - nullableArg"))
 }
 
 // InputSlice is the resolver for the inputSlice field.
 func (r *queryResolver) InputSlice(ctx context.Context, arg []string) (bool, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: InputSlice - inputSlice"))
 }
 
 // InputNullableSlice is the resolver for the inputNullableSlice field.
 func (r *queryResolver) InputNullableSlice(ctx context.Context, arg []string) (bool, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: InputNullableSlice - inputNullableSlice"))
 }
 
 // InputOmittable is the resolver for the inputOmittable field.
 func (r *queryResolver) InputOmittable(ctx context.Context, arg OmittableInput) (string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: InputOmittable - inputOmittable"))
 }
 
 // ShapeUnion is the resolver for the shapeUnion field.
 func (r *queryResolver) ShapeUnion(ctx context.Context) (ShapeUnion, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: ShapeUnion - shapeUnion"))
 }
 
 // Autobind is the resolver for the autobind field.
 func (r *queryResolver) Autobind(ctx context.Context) (*Autobind, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Autobind - autobind"))
 }
 
 // DeprecatedField is the resolver for the deprecatedField field.
 func (r *queryResolver) DeprecatedField(ctx context.Context) (string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: DeprecatedField - deprecatedField"))
 }
 
 // Overlapping is the resolver for the overlapping field.
 func (r *queryResolver) Overlapping(ctx context.Context) (*OverlappingFields, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Overlapping - overlapping"))
 }
 
 // DefaultParameters is the resolver for the defaultParameters field.
 func (r *queryResolver) DefaultParameters(ctx context.Context, falsyBoolean *bool, truthyBoolean *bool) (*DefaultParametersMirror, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: DefaultParameters - defaultParameters"))
 }
 
 // DeferCase1 is the resolver for the deferCase1 field.
 func (r *queryResolver) DeferCase1(ctx context.Context) (*DeferModel, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: DeferCase1 - deferCase1"))
 }
 
 // DeferCase2 is the resolver for the deferCase2 field.
 func (r *queryResolver) DeferCase2(ctx context.Context) ([]*DeferModel, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: DeferCase2 - deferCase2"))
 }
 
 // DirectiveArg is the resolver for the directiveArg field.
 func (r *queryResolver) DirectiveArg(ctx context.Context, arg string) (*string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: DirectiveArg - directiveArg"))
 }
 
 // DirectiveNullableArg is the resolver for the directiveNullableArg field.
 func (r *queryResolver) DirectiveNullableArg(ctx context.Context, arg *int, arg2 *int, arg3 *string) (*string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: DirectiveNullableArg - directiveNullableArg"))
 }
 
 // DirectiveSingleNullableArg is the resolver for the directiveSingleNullableArg field.
 func (r *queryResolver) DirectiveSingleNullableArg(ctx context.Context, arg1 *string) (*string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: DirectiveSingleNullableArg - directiveSingleNullableArg"))
 }
 
 // DirectiveInputNullable is the resolver for the directiveInputNullable field.
 func (r *queryResolver) DirectiveInputNullable(ctx context.Context, arg *InputDirectives) (*string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: DirectiveInputNullable - directiveInputNullable"))
 }
 
 // DirectiveInput is the resolver for the directiveInput field.
 func (r *queryResolver) DirectiveInput(ctx context.Context, arg InputDirectives) (*string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: DirectiveInput - directiveInput"))
 }
 
 // DirectiveInputType is the resolver for the directiveInputType field.
 func (r *queryResolver) DirectiveInputType(ctx context.Context, arg InnerInput) (*string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: DirectiveInputType - directiveInputType"))
 }
 
 // DirectiveObject is the resolver for the directiveObject field.
 func (r *queryResolver) DirectiveObject(ctx context.Context) (*ObjectDirectives, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: DirectiveObject - directiveObject"))
 }
 
 // DirectiveObjectWithCustomGoModel is the resolver for the directiveObjectWithCustomGoModel field.
 func (r *queryResolver) DirectiveObjectWithCustomGoModel(ctx context.Context) (*ObjectDirectivesWithCustomGoModel, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: DirectiveObjectWithCustomGoModel - directiveObjectWithCustomGoModel"))
 }
 
 // DirectiveFieldDef is the resolver for the directiveFieldDef field.
 func (r *queryResolver) DirectiveFieldDef(ctx context.Context, ret string) (string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: DirectiveFieldDef - directiveFieldDef"))
 }
 
 // DirectiveField is the resolver for the directiveField field.
 func (r *queryResolver) DirectiveField(ctx context.Context) (*string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: DirectiveField - directiveField"))
 }
 
 // DirectiveDouble is the resolver for the directiveDouble field.
 func (r *queryResolver) DirectiveDouble(ctx context.Context) (*string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: DirectiveDouble - directiveDouble"))
 }
 
 // DirectiveUnimplemented is the resolver for the directiveUnimplemented field.
 func (r *queryResolver) DirectiveUnimplemented(ctx context.Context) (*string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: DirectiveUnimplemented - directiveUnimplemented"))
 }
 
 // DirectiveConcurrent is the resolver for the directiveConcurrent field.
 func (r *queryResolver) DirectiveConcurrent(ctx context.Context) ([]*ObjectDirectivesConcurrent, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: DirectiveConcurrent - directiveConcurrent"))
 }
 
 // EmbeddedCase1 is the resolver for the embeddedCase1 field.
 func (r *queryResolver) EmbeddedCase1(ctx context.Context) (*EmbeddedCase1, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: EmbeddedCase1 - embeddedCase1"))
 }
 
 // EmbeddedCase2 is the resolver for the embeddedCase2 field.
 func (r *queryResolver) EmbeddedCase2(ctx context.Context) (*EmbeddedCase2, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: EmbeddedCase2 - embeddedCase2"))
 }
 
 // EmbeddedCase3 is the resolver for the embeddedCase3 field.
 func (r *queryResolver) EmbeddedCase3(ctx context.Context) (*EmbeddedCase3, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: EmbeddedCase3 - embeddedCase3"))
 }
 
 // EnumInInput is the resolver for the enumInInput field.
 func (r *queryResolver) EnumInInput(ctx context.Context, input *InputWithEnumValue) (EnumTest, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: EnumInInput - enumInInput"))
 }
 
 // Shapes is the resolver for the shapes field.
 func (r *queryResolver) Shapes(ctx context.Context) ([]Shape, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Shapes - shapes"))
 }
 
 // NoShape is the resolver for the noShape field.
 func (r *queryResolver) NoShape(ctx context.Context) (Shape, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: NoShape - noShape"))
 }
 
 // Node is the resolver for the node field.
 func (r *queryResolver) Node(ctx context.Context) (Node, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Node - node"))
 }
 
 // NoShapeTypedNil is the resolver for the noShapeTypedNil field.
 func (r *queryResolver) NoShapeTypedNil(ctx context.Context) (Shape, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: NoShapeTypedNil - noShapeTypedNil"))
 }
 
 // Animal is the resolver for the animal field.
 func (r *queryResolver) Animal(ctx context.Context) (Animal, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Animal - animal"))
 }
 
 // NotAnInterface is the resolver for the notAnInterface field.
 func (r *queryResolver) NotAnInterface(ctx context.Context) (BackedByInterface, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: NotAnInterface - notAnInterface"))
 }
 
 // Dog is the resolver for the dog field.
 func (r *queryResolver) Dog(ctx context.Context) (*Dog, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Dog - dog"))
 }
 
 // Issue896a is the resolver for the issue896a field.
 func (r *queryResolver) Issue896a(ctx context.Context) ([]*CheckIssue896, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Issue896a - issue896a"))
 }
 
 // MapStringInterface is the resolver for the mapStringInterface field.
 func (r *queryResolver) MapStringInterface(ctx context.Context, in map[string]interface{}) (map[string]interface{}, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: MapStringInterface - mapStringInterface"))
 }
 
 // MapNestedStringInterface is the resolver for the mapNestedStringInterface field.
 func (r *queryResolver) MapNestedStringInterface(ctx context.Context, in *NestedMapInput) (map[string]interface{}, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: MapNestedStringInterface - mapNestedStringInterface"))
 }
 
 // ErrorBubble is the resolver for the errorBubble field.
 func (r *queryResolver) ErrorBubble(ctx context.Context) (*Error, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: ErrorBubble - errorBubble"))
 }
 
 // ErrorBubbleList is the resolver for the errorBubbleList field.
 func (r *queryResolver) ErrorBubbleList(ctx context.Context) ([]*Error, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: ErrorBubbleList - errorBubbleList"))
 }
 
 // ErrorList is the resolver for the errorList field.
 func (r *queryResolver) ErrorList(ctx context.Context) ([]*Error, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: ErrorList - errorList"))
 }
 
 // Errors is the resolver for the errors field.
 func (r *queryResolver) Errors(ctx context.Context) (*Errors, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Errors - errors"))
 }
 
 // Valid is the resolver for the valid field.
 func (r *queryResolver) Valid(ctx context.Context) (string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Valid - valid"))
 }
 
 // Invalid is the resolver for the invalid field.
 func (r *queryResolver) Invalid(ctx context.Context) (string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Invalid - invalid"))
 }
 
 // Panics is the resolver for the panics field.
 func (r *queryResolver) Panics(ctx context.Context) (*Panics, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Panics - panics"))
 }
 
 // PrimitiveObject is the resolver for the primitiveObject field.
 func (r *queryResolver) PrimitiveObject(ctx context.Context) ([]Primitive, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: PrimitiveObject - primitiveObject"))
 }
 
 // PrimitiveStringObject is the resolver for the primitiveStringObject field.
 func (r *queryResolver) PrimitiveStringObject(ctx context.Context) ([]PrimitiveString, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: PrimitiveStringObject - primitiveStringObject"))
 }
 
 // PtrToAnyContainer is the resolver for the ptrToAnyContainer field.
 func (r *queryResolver) PtrToAnyContainer(ctx context.Context) (*PtrToAnyContainer, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: PtrToAnyContainer - ptrToAnyContainer"))
 }
 
 // PtrToSliceContainer is the resolver for the ptrToSliceContainer field.
 func (r *queryResolver) PtrToSliceContainer(ctx context.Context) (*PtrToSliceContainer, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: PtrToSliceContainer - ptrToSliceContainer"))
 }
 
 // Infinity is the resolver for the infinity field.
 func (r *queryResolver) Infinity(ctx context.Context) (float64, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Infinity - infinity"))
 }
 
 // StringFromContextInterface is the resolver for the stringFromContextInterface field.
 func (r *queryResolver) StringFromContextInterface(ctx context.Context) (*StringFromContextInterface, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: StringFromContextInterface - stringFromContextInterface"))
 }
 
 // StringFromContextFunction is the resolver for the stringFromContextFunction field.
 func (r *queryResolver) StringFromContextFunction(ctx context.Context) (string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: StringFromContextFunction - stringFromContextFunction"))
 }
 
 // DefaultScalar is the resolver for the defaultScalar field.
 func (r *queryResolver) DefaultScalar(ctx context.Context, arg string) (string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: DefaultScalar - defaultScalar"))
 }
 
 // Slices is the resolver for the slices field.
 func (r *queryResolver) Slices(ctx context.Context) (*Slices, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Slices - slices"))
 }
 
 // ScalarSlice is the resolver for the scalarSlice field.
 func (r *queryResolver) ScalarSlice(ctx context.Context) ([]byte, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: ScalarSlice - scalarSlice"))
 }
 
 // Fallback is the resolver for the fallback field.
 func (r *queryResolver) Fallback(ctx context.Context, arg FallbackToStringEncoding) (FallbackToStringEncoding, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Fallback - fallback"))
 }
 
 // OptionalUnion is the resolver for the optionalUnion field.
 func (r *queryResolver) OptionalUnion(ctx context.Context) (TestUnion, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: OptionalUnion - optionalUnion"))
 }
 
 // VOkCaseValue is the resolver for the vOkCaseValue field.
 func (r *queryResolver) VOkCaseValue(ctx context.Context) (*VOkCaseValue, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: VOkCaseValue - vOkCaseValue"))
 }
 
 // VOkCaseNil is the resolver for the vOkCaseNil field.
 func (r *queryResolver) VOkCaseNil(ctx context.Context) (*VOkCaseNil, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: VOkCaseNil - vOkCaseNil"))
 }
 
 // ValidType is the resolver for the validType field.
 func (r *queryResolver) ValidType(ctx context.Context) (*ValidType, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: ValidType - validType"))
 }
 
 // VariadicModel is the resolver for the variadicModel field.
 func (r *queryResolver) VariadicModel(ctx context.Context) (*VariadicModel, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: VariadicModel - variadicModel"))
 }
 
 // WrappedStruct is the resolver for the wrappedStruct field.
 func (r *queryResolver) WrappedStruct(ctx context.Context) (*WrappedStruct, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: WrappedStruct - wrappedStruct"))
 }
 
 // WrappedScalar is the resolver for the wrappedScalar field.
 func (r *queryResolver) WrappedScalar(ctx context.Context) (otherpkg.Scalar, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: WrappedScalar - wrappedScalar"))
 }
 
 // WrappedMap is the resolver for the wrappedMap field.
 func (r *queryResolver) WrappedMap(ctx context.Context) (WrappedMap, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: WrappedMap - wrappedMap"))
 }
 
 // WrappedSlice is the resolver for the wrappedSlice field.
 func (r *queryResolver) WrappedSlice(ctx context.Context) (WrappedSlice, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: WrappedSlice - wrappedSlice"))
 }
 
 // Updated is the resolver for the updated field.
 func (r *subscriptionResolver) Updated(ctx context.Context) (<-chan string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Updated - updated"))
 }
 
 // InitPayload is the resolver for the initPayload field.
 func (r *subscriptionResolver) InitPayload(ctx context.Context) (<-chan string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: InitPayload - initPayload"))
 }
 
 // DirectiveArg is the resolver for the directiveArg field.
 func (r *subscriptionResolver) DirectiveArg(ctx context.Context, arg string) (<-chan *string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: DirectiveArg - directiveArg"))
 }
 
 // DirectiveNullableArg is the resolver for the directiveNullableArg field.
 func (r *subscriptionResolver) DirectiveNullableArg(ctx context.Context, arg *int, arg2 *int, arg3 *string) (<-chan *string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: DirectiveNullableArg - directiveNullableArg"))
 }
 
 // DirectiveDouble is the resolver for the directiveDouble field.
 func (r *subscriptionResolver) DirectiveDouble(ctx context.Context) (<-chan *string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: DirectiveDouble - directiveDouble"))
 }
 
 // DirectiveUnimplemented is the resolver for the directiveUnimplemented field.
 func (r *subscriptionResolver) DirectiveUnimplemented(ctx context.Context) (<-chan *string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: DirectiveUnimplemented - directiveUnimplemented"))
 }
 
 // Issue896b is the resolver for the issue896b field.
 func (r *subscriptionResolver) Issue896b(ctx context.Context) (<-chan []*CheckIssue896, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Issue896b - issue896b"))
 }
 
 // ErrorRequired is the resolver for the errorRequired field.
 func (r *subscriptionResolver) ErrorRequired(ctx context.Context) (<-chan *Error, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: ErrorRequired - errorRequired"))
 }
 
 // Friends is the resolver for the friends field.
 func (r *userResolver) Friends(ctx context.Context, obj *User) ([]*User, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Friends - friends"))
 }
 
 // Pets is the resolver for the pets field.
 func (r *userResolver) Pets(ctx context.Context, obj *User, limit *int) ([]*Pet, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Pets - pets"))
 }
 
 // Get is the resolver for the get field.
 func (r *wrappedMapResolver) Get(ctx context.Context, obj WrappedMap, key string) (string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Get - get"))
 }
 
 // Get is the resolver for the get field.
 func (r *wrappedSliceResolver) Get(ctx context.Context, obj WrappedSlice, idx int) (string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Get - get"))
 }
 
 // BackedByInterface returns BackedByInterfaceResolver implementation.
diff --git a/integration/server/gqlgen.yml b/integration/server/gqlgen.yml
index 427490c7ef..9195079be1 100644
--- a/integration/server/gqlgen.yml
+++ b/integration/server/gqlgen.yml
@@ -5,9 +5,6 @@ exec:
   filename: generated.go
 model:
   filename: models-go/generated.go
-resolver:
-  filename: resolver.go
-  type: Resolver
 
 struct_tag: json
 
diff --git a/plugin/resolvergen/resolver.go b/plugin/resolvergen/resolver.go
index 38138d5201..c50b476366 100644
--- a/plugin/resolvergen/resolver.go
+++ b/plugin/resolvergen/resolver.go
@@ -53,26 +53,40 @@ func (m *Plugin) GenerateCode(data *codegen.Data) error {
 
 func (m *Plugin) generateSingleFile(data *codegen.Data) error {
 	file := File{}
-
-	if _, err := os.Stat(data.Config.Resolver.Filename); err == nil {
-		// file already exists and we do not support updating resolvers with layout = single so just return
-		return nil
+	rewriter, err := rewrite.New(data.Config.Resolver.Dir())
+	if err != nil {
+		return err
 	}
 
 	for _, o := range data.Objects {
 		if o.HasResolvers() {
+			caser := cases.Title(language.English, cases.NoLower)
+			rewriter.MarkStructCopied(templates.LcFirst(o.Name) + templates.UcFirst(data.Config.Resolver.Type))
+			rewriter.GetMethodBody(data.Config.Resolver.Type, caser.String(o.Name))
+
 			file.Objects = append(file.Objects, o)
 		}
+
 		for _, f := range o.Fields {
 			if !f.IsResolver {
 				continue
 			}
 
-			resolver := Resolver{o, f, nil, "", `panic("not implemented")`, nil}
+			structName := templates.LcFirst(o.Name) + templates.UcFirst(data.Config.Resolver.Type)
+			comment := strings.TrimSpace(strings.TrimLeft(rewriter.GetMethodComment(structName, f.GoFieldName), `\`))
+			implementation := strings.TrimSpace(rewriter.GetMethodBody(structName, f.GoFieldName))
+
+			resolver := Resolver{o, f, rewriter.GetPrevDecl(structName, f.GoFieldName), comment, implementation, nil}
 			file.Resolvers = append(file.Resolvers, &resolver)
 		}
 	}
 
+	if _, err := os.Stat(data.Config.Resolver.Filename); err == nil {
+		file.name = data.Config.Resolver.Filename
+		file.imports = rewriter.ExistingImports(file.name)
+		file.RemainingSource = rewriter.RemainingSource(file.name)
+	}
+
 	resolverBuild := &ResolverBuild{
 		File:                &file,
 		PackageName:         data.Config.Resolver.Package,
@@ -88,7 +102,7 @@ func (m *Plugin) generateSingleFile(data *codegen.Data) error {
 
 	return templates.Render(templates.Options{
 		PackageName: data.Config.Resolver.Package,
-		FileNotice:  `// THIS CODE IS A STARTING POINT ONLY. IT WILL NOT BE UPDATED WITH SCHEMA CHANGES.`,
+		FileNotice:  `// THIS CODE WILL BE UPDATED WITH SCHEMA CHANGES. PREVIOUS IMPLEMENTATION FOR SCHEMA CHANGES WILL BE KEPT IN THE COMMENT SECTION. IMPLEMENTATION FOR UNCHANGED SCHEMA WILL BE KEPT.`,
 		Filename:    data.Config.Resolver.Filename,
 		Data:        resolverBuild,
 		Packages:    data.Config.Packages,
diff --git a/plugin/resolvergen/resolver.gotpl b/plugin/resolvergen/resolver.gotpl
index c25bd1d562..ad6c108581 100644
--- a/plugin/resolvergen/resolver.gotpl
+++ b/plugin/resolvergen/resolver.gotpl
@@ -48,5 +48,7 @@
 	//  - When renaming or deleting a resolver the old code will be put in here. You can safely delete
 	//    it when you're done.
 	//  - You have helper methods in this file. Move them out to keep these resolver files clean.
+	/*
 	{{ .RemainingSource }}
+	*/
 {{ end }}
diff --git a/plugin/resolvergen/testdata/singlefile/out/resolver.go b/plugin/resolvergen/testdata/singlefile/out/resolver.go
index 844b077c4a..614c66cf18 100644
--- a/plugin/resolvergen/testdata/singlefile/out/resolver.go
+++ b/plugin/resolvergen/testdata/singlefile/out/resolver.go
@@ -1,21 +1,22 @@
 package customresolver
 
-// THIS CODE IS A STARTING POINT ONLY. IT WILL NOT BE UPDATED WITH SCHEMA CHANGES.
+// THIS CODE WILL BE UPDATED WITH SCHEMA CHANGES. PREVIOUS IMPLEMENTATION FOR SCHEMA CHANGES WILL BE KEPT IN THE COMMENT SECTION. IMPLEMENTATION FOR UNCHANGED SCHEMA WILL BE KEPT.
 
 import (
 	"context"
+	"fmt"
 )
 
 type CustomResolverType struct{}
 
 // Resolver is the resolver for the resolver field.
 func (r *queryCustomResolverType) Resolver(ctx context.Context) (*Resolver, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Resolver - resolver"))
 }
 
 // Name is the resolver for the name field.
 func (r *resolverCustomResolverType) Name(ctx context.Context, obj *Resolver) (string, error) {
-	panic("not implemented")
+	panic(fmt.Errorf("not implemented: Name - name"))
 }
 
 // Query returns QueryResolver implementation.