From 76aa8907d85837ba4ac4b2050fcbd3937bef7a8f Mon Sep 17 00:00:00 2001
From: Allen Zhong <zhongbenli@pingcap.com>
Date: Tue, 21 Jul 2020 17:40:23 +0800
Subject: [PATCH] utils/diff: use better error message

---
 pkg/utils/diff.go      | 11 ++++++++++-
 pkg/utils/diff_test.go | 16 ++++++++--------
 2 files changed, 18 insertions(+), 9 deletions(-)

diff --git a/pkg/utils/diff.go b/pkg/utils/diff.go
index c9d924c201..2c7e7dc3ed 100644
--- a/pkg/utils/diff.go
+++ b/pkg/utils/diff.go
@@ -94,7 +94,16 @@ func ValidateSpecDiff(s1, s2 interface{}) error {
 				continue
 			}
 		}
-		msg = append(msg, fmt.Sprintf("(%s) %s '%v' -> '%v'", c.Type, buildFieldPath(c.Path), c.From, c.To))
+
+		// build error messages
+		switch c.Type {
+		case diff.CREATE:
+			msg = append(msg, fmt.Sprintf("added %s with value '%v'", buildFieldPath(c.Path), c.To))
+		case diff.DELETE:
+			msg = append(msg, fmt.Sprintf("removed %s with value '%v'", buildFieldPath(c.Path), c.From))
+		case diff.UPDATE:
+			msg = append(msg, fmt.Sprintf("%s changed from '%v' to '%v'", buildFieldPath(c.Path), c.From, c.To))
+		}
 	}
 
 	if len(msg) > 0 {
diff --git a/pkg/utils/diff_test.go b/pkg/utils/diff_test.go
index c858aef5c0..24539e20bf 100644
--- a/pkg/utils/diff_test.go
+++ b/pkg/utils/diff_test.go
@@ -70,7 +70,7 @@ strs:
 	err = ValidateSpecDiff(d1, d2)
 	c.Assert(err, IsNil)
 
-	// add editable element
+	// add editable element (without specifing alias)
 	err = yaml.Unmarshal([]byte(`
 ints: [11, 13, 12]
 strs:
@@ -89,7 +89,7 @@ ints: [11, 12, 13, 14]
 	c.Assert(err, IsNil)
 	err = ValidateSpecDiff(d1, d2)
 	c.Assert(err, NotNil)
-	c.Assert(err.Error(), Equals, "immutable field changed: (create) IntSlice.3 '<nil>' -> '14'")
+	c.Assert(err.Error(), Equals, "immutable field changed: added IntSlice.3 with value '14'")
 }
 
 func (d *diffSuite) TestValidateSpecDiff2(c *C) {
@@ -144,7 +144,7 @@ slice1:
 	c.Assert(err, IsNil)
 	err = ValidateSpecDiff(d1, d2)
 	c.Assert(err, NotNil)
-	c.Assert(err.Error(), Equals, "immutable field changed: (update) slice1.1.IntElem '42' -> '43'")
+	c.Assert(err.Error(), Equals, "immutable field changed: slice1.1.IntElem changed from '42' to '43'")
 
 	// Add item with immutable field to editable slice
 	err = yaml.Unmarshal([]byte(`
@@ -166,7 +166,7 @@ slice1:
 	c.Assert(err, IsNil)
 	err = ValidateSpecDiff(d1, d2)
 	c.Assert(err, NotNil)
-	c.Assert(err.Error(), Equals, "immutable field changed: (create) slice1.2.IntElem '<nil>' -> '42'")
+	c.Assert(err.Error(), Equals, "immutable field changed: added slice1.2.IntElem with value '42'")
 
 	// Delete item with immutable field from editable slice
 	err = yaml.Unmarshal([]byte(`
@@ -180,7 +180,7 @@ slice1:
 	c.Assert(err, IsNil)
 	err = ValidateSpecDiff(d1, d2)
 	c.Assert(err, NotNil)
-	c.Assert(err.Error(), Equals, "immutable field changed: (delete) slice1.1.IntElem '42' -> '<nil>'")
+	c.Assert(err.Error(), Equals, "immutable field changed: removed slice1.1.IntElem with value '42'")
 }
 
 func (d *diffSuite) TestValidateSpecDiff3(c *C) {
@@ -235,7 +235,7 @@ slice2:
 	c.Assert(err, IsNil)
 	err = ValidateSpecDiff(d1, d2)
 	c.Assert(err, NotNil)
-	c.Assert(err.Error(), Equals, "immutable field changed: (update) StructSlice2.1.IntElem '42' -> '43'")
+	c.Assert(err.Error(), Equals, "immutable field changed: StructSlice2.1.IntElem changed from '42' to '43'")
 
 	// Add item to immutable slice
 	err = yaml.Unmarshal([]byte(`
@@ -255,7 +255,7 @@ slice2:
 	c.Assert(err, IsNil)
 	err = ValidateSpecDiff(d1, d2)
 	c.Assert(err, NotNil)
-	c.Assert(err.Error(), Equals, "immutable field changed: (create) StructSlice2.2.str1 '<nil>' -> 'strv31', (create) StructSlice2.2.str2 '<nil>' -> 'strv32'")
+	c.Assert(err.Error(), Equals, "immutable field changed: added StructSlice2.2.str1 with value 'strv31', added StructSlice2.2.str2 with value 'strv32'")
 
 	// Remove item from immutable slice
 	err = yaml.Unmarshal([]byte(`
@@ -269,7 +269,7 @@ slice2:
 	c.Assert(err, IsNil)
 	err = ValidateSpecDiff(d1, d2)
 	c.Assert(err, NotNil)
-	c.Assert(err.Error(), Equals, "immutable field changed: (delete) StructSlice2.1.str1 'strv12' -> '<nil>', (delete) StructSlice2.1.str2 'strv22' -> '<nil>', (delete) StructSlice2.1.IntElem '42' -> '<nil>', (delete) StructSlice2.1.interface '12' -> '<nil>'")
+	c.Assert(err.Error(), Equals, "immutable field changed: removed StructSlice2.1.str1 with value 'strv12', removed StructSlice2.1.str2 with value 'strv22', removed StructSlice2.1.IntElem with value '42', removed StructSlice2.1.interface with value '12'")
 }
 
 func (d *diffSuite) TestValidateSpecDiff4(c *C) {