From 2bde0593131b299b5f8d7da100122c8a2b74fd39 Mon Sep 17 00:00:00 2001
From: Tyler Yahn <codingalias@gmail.com>
Date: Tue, 2 Aug 2022 09:02:10 -0700
Subject: [PATCH 01/20] PoC stdoutmetric exporter

---
 .github/dependabot.yml                        |   9 +
 exporters/stdout/stdoutmetric/config.go       |  66 ++++++
 exporters/stdout/stdoutmetric/doc.go          |  22 ++
 exporters/stdout/stdoutmetric/encoder.go      |  49 ++++
 exporters/stdout/stdoutmetric/example_test.go | 220 ++++++++++++++++++
 exporters/stdout/stdoutmetric/exporter.go     |  75 ++++++
 exporters/stdout/stdoutmetric/go.mod          |  27 +++
 exporters/stdout/stdoutmetric/go.sum          |  12 +
 sdk/instrumentation/scope.go                  |   2 +-
 sdk/metric/metricdata/data.go                 |   8 +-
 sdk/metric/metricdata/temporality.go          |  15 ++
 11 files changed, 500 insertions(+), 5 deletions(-)
 create mode 100644 exporters/stdout/stdoutmetric/config.go
 create mode 100644 exporters/stdout/stdoutmetric/doc.go
 create mode 100644 exporters/stdout/stdoutmetric/encoder.go
 create mode 100644 exporters/stdout/stdoutmetric/example_test.go
 create mode 100644 exporters/stdout/stdoutmetric/exporter.go
 create mode 100644 exporters/stdout/stdoutmetric/go.mod
 create mode 100644 exporters/stdout/stdoutmetric/go.sum

diff --git a/.github/dependabot.yml b/.github/dependabot.yml
index 556c5ad0309..cd0fec29c29 100644
--- a/.github/dependabot.yml
+++ b/.github/dependabot.yml
@@ -127,6 +127,15 @@ updates:
     schedule:
       interval: weekly
       day: sunday
+  - package-ecosystem: gomod
+    directory: /exporters/stdout/stdoutmetric
+    labels:
+      - dependencies
+      - go
+      - Skip Changelog
+    schedule:
+      interval: weekly
+      day: sunday
   - package-ecosystem: gomod
     directory: /exporters/stdout/stdouttrace
     labels:
diff --git a/exporters/stdout/stdoutmetric/config.go b/exporters/stdout/stdoutmetric/config.go
new file mode 100644
index 00000000000..04168a3867a
--- /dev/null
+++ b/exporters/stdout/stdoutmetric/config.go
@@ -0,0 +1,66 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build go1.18
+// +build go1.18
+
+package stdoutmetric
+
+import (
+	"encoding/json"
+	"os"
+)
+
+// config contains options for the exporter.
+type config struct {
+	encoder *encoderHolder
+}
+
+// newConfig creates a validated config configured with options.
+func newConfig(options ...Option) (config, error) {
+	cfg := config{}
+	for _, opt := range options {
+		cfg = opt.apply(cfg)
+	}
+
+	if cfg.encoder == nil {
+		enc := json.NewEncoder(os.Stdout)
+		enc.SetIndent("", "\t")
+		cfg.encoder = &encoderHolder{encoder: enc}
+	}
+
+	return cfg, nil
+}
+
+// Option sets exporter option values.
+type Option interface {
+	apply(config) config
+}
+
+type optionFunc func(config) config
+
+func (o optionFunc) apply(c config) config {
+	return o(c)
+}
+
+// WithEncoder sets the exporter to use ecoder to encode all the metric
+// data-types to an output.
+func WithEncoder(encoder Encoder) Option {
+	return optionFunc(func(c config) config {
+		if encoder != nil {
+			c.encoder = &encoderHolder{encoder: encoder}
+		}
+		return c
+	})
+}
diff --git a/exporters/stdout/stdoutmetric/doc.go b/exporters/stdout/stdoutmetric/doc.go
new file mode 100644
index 00000000000..4710c73f2f3
--- /dev/null
+++ b/exporters/stdout/stdoutmetric/doc.go
@@ -0,0 +1,22 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package stdoutmetric provides an exporter for OpenTelemetry metric
+// telemetry.
+//
+// The exporter is intended to be used for testing and debugging. It is not an
+// exporter meant for production use. Additionally, it does not provide an
+// interchange format for OpenTelemetry that is supported with any stability
+// or compatibility guarantees. Please use the OTLP instead.
+package stdoutmetric // import "go.opentelemetry.io/otel/exporters/stdout/stdoutmetric"
diff --git a/exporters/stdout/stdoutmetric/encoder.go b/exporters/stdout/stdoutmetric/encoder.go
new file mode 100644
index 00000000000..dbfc78e493a
--- /dev/null
+++ b/exporters/stdout/stdoutmetric/encoder.go
@@ -0,0 +1,49 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build go1.18
+// +build go1.18
+
+package stdoutmetric
+
+import "errors"
+
+var ErrUnrecognized = errors.New("unrecognized metric data")
+
+// Encoder encodes and outputs OpenTelemetry metric data-types as human
+// readable text.
+type Encoder interface {
+	// Encode handles the encoding and writing OpenTelemetry metric data-types
+	// that the exporter will pass to it.
+	//
+	// Any data-type that is not recognized by the encoder and not output to
+	// the user, will have an ErrUnrecognized returned from Encode.
+	Encode(v any) error
+}
+
+// encoderHolder is the concrete type used to wrap an Encoder so it can be
+// used as a atomic.Value type.
+type encoderHolder struct {
+	encoder Encoder
+}
+
+func (e encoderHolder) Encode(v any) error { return e.encoder.Encode(v) }
+
+// shutdownEncoder is used when the exporter is shutdown. It always returns
+// errShutdown when Encode is called.
+type shutdownEncoder struct{}
+
+var errShutdown = errors.New("exporter shutdown")
+
+func (shutdownEncoder) Encode(any) error { return errShutdown }
diff --git a/exporters/stdout/stdoutmetric/example_test.go b/exporters/stdout/stdoutmetric/example_test.go
new file mode 100644
index 00000000000..7403c03c3fc
--- /dev/null
+++ b/exporters/stdout/stdoutmetric/example_test.go
@@ -0,0 +1,220 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build go1.18
+// +build go1.18
+
+package stdoutmetric_test
+
+import (
+	"context"
+	"encoding/json"
+	"os"
+	"time"
+
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/exporters/stdout/stdoutmetric"
+	"go.opentelemetry.io/otel/metric/unit"
+	"go.opentelemetry.io/otel/sdk/instrumentation"
+	"go.opentelemetry.io/otel/sdk/metric/metricdata"
+	"go.opentelemetry.io/otel/sdk/resource"
+	semconv "go.opentelemetry.io/otel/semconv/v1.10.0"
+)
+
+// Sat Jan 01 2000 00:00:00 GMT+0000.
+var now = time.Unix(946684800, 0)
+
+var mockData = metricdata.ResourceMetrics{
+	Resource: resource.NewSchemaless(semconv.ServiceNameKey.String("stdoutmetric-example")),
+	ScopeMetrics: []metricdata.ScopeMetrics{
+		{
+			Scope: instrumentation.Scope{
+				Name:    "example",
+				Version: "v0.0.1",
+			},
+			Metrics: []metricdata.Metrics{
+				{
+					Name:        "requests",
+					Description: "Number of requests received",
+					Unit:        unit.Dimensionless,
+					Data: metricdata.Sum[int64]{
+						IsMonotonic: true,
+						Temporality: metricdata.DeltaTemporality,
+						DataPoints: []metricdata.DataPoint[int64]{
+							{
+								Attributes: attribute.NewSet(attribute.String("server", "central")),
+								StartTime:  now,
+								Time:       now.Add(1 * time.Second),
+								Value:      5,
+							},
+						},
+					},
+				},
+				{
+					Name:        "latency",
+					Description: "Time spend processing received requests",
+					Unit:        unit.Milliseconds,
+					Data: metricdata.Histogram{
+						Temporality: metricdata.DeltaTemporality,
+						DataPoints: []metricdata.HistogramDataPoint{
+							{
+								Attributes:   attribute.NewSet(attribute.String("server", "central")),
+								StartTime:    now,
+								Time:         now.Add(1 * time.Second),
+								Count:        10,
+								Bounds:       []float64{1, 5, 10},
+								BucketCounts: []uint64{1, 3, 6, 0},
+								Sum:          57,
+							},
+						},
+					},
+				},
+				{
+					Name:        "temperature",
+					Description: "CPU global temperature",
+					Unit:        unit.Unit("cel(1 K)"),
+					Data: metricdata.Gauge[float64]{
+						DataPoints: []metricdata.DataPoint[float64]{
+							{
+								Attributes: attribute.NewSet(attribute.String("server", "central")),
+								Time:       now.Add(1 * time.Second),
+								Value:      32.4,
+							},
+						},
+					},
+				},
+			},
+		},
+	},
+}
+
+func Example() {
+	// Print with a JSON encoder that indents with two spaces.
+	enc := json.NewEncoder(os.Stdout)
+	enc.SetIndent("", "  ")
+	exp, err := stdoutmetric.New(stdoutmetric.WithEncoder(enc))
+	if err != nil {
+		panic(err)
+	}
+	// FIXME: The exporter should be registered with an SDK and the output
+	// should come from that.
+	exp.Export(context.Background(), mockData)
+
+	// Output:
+	// {
+	//   "Resource": [
+	//     {
+	//       "Key": "service.name",
+	//       "Value": {
+	//         "Type": "STRING",
+	//         "Value": "stdoutmetric-example"
+	//       }
+	//     }
+	//   ],
+	//   "ScopeMetrics": [
+	//     {
+	//       "Scope": {
+	//         "Name": "example",
+	//         "Version": "v0.0.1"
+	//       },
+	//       "Metrics": [
+	//         {
+	//           "Name": "requests",
+	//           "Description": "Number of requests received",
+	//           "Unit": "1",
+	//           "Data": {
+	//             "DataPoints": [
+	//               {
+	//                 "Attributes": [
+	//                   {
+	//                     "Key": "server",
+	//                     "Value": {
+	//                       "Type": "STRING",
+	//                       "Value": "central"
+	//                     }
+	//                   }
+	//                 ],
+	//                 "StartTime": "1999-12-31T16:00:00-08:00",
+	//                 "Time": "1999-12-31T16:00:01-08:00",
+	//                 "Value": 5
+	//               }
+	//             ],
+	//             "Temporality": "delta",
+	//             "IsMonotonic": true
+	//           }
+	//         },
+	//         {
+	//           "Name": "latency",
+	//           "Description": "Time spend processing received requests",
+	//           "Unit": "ms",
+	//           "Data": {
+	//             "DataPoints": [
+	//               {
+	//                 "Attributes": [
+	//                   {
+	//                     "Key": "server",
+	//                     "Value": {
+	//                       "Type": "STRING",
+	//                       "Value": "central"
+	//                     }
+	//                   }
+	//                 ],
+	//                 "StartTime": "1999-12-31T16:00:00-08:00",
+	//                 "Time": "1999-12-31T16:00:01-08:00",
+	//                 "Count": 10,
+	//                 "Bounds": [
+	//                   1,
+	//                   5,
+	//                   10
+	//                 ],
+	//                 "BucketCounts": [
+	//                   1,
+	//                   3,
+	//                   6,
+	//                   0
+	//                 ],
+	//                 "Sum": 57
+	//               }
+	//             ],
+	//             "Temporality": "delta"
+	//           }
+	//         },
+	//         {
+	//           "Name": "temperature",
+	//           "Description": "CPU global temperature",
+	//           "Unit": "cel(1 K)",
+	//           "Data": {
+	//             "DataPoints": [
+	//               {
+	//                 "Attributes": [
+	//                   {
+	//                     "Key": "server",
+	//                     "Value": {
+	//                       "Type": "STRING",
+	//                       "Value": "central"
+	//                     }
+	//                   }
+	//                 ],
+	//                 "StartTime": "0001-01-01T00:00:00Z",
+	//                 "Time": "1999-12-31T16:00:01-08:00",
+	//                 "Value": 32.4
+	//               }
+	//             ]
+	//           }
+	//         }
+	//       ]
+	//     }
+	//   ]
+	// }
+}
diff --git a/exporters/stdout/stdoutmetric/exporter.go b/exporters/stdout/stdoutmetric/exporter.go
new file mode 100644
index 00000000000..084c887c9bb
--- /dev/null
+++ b/exporters/stdout/stdoutmetric/exporter.go
@@ -0,0 +1,75 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build go1.18
+// +build go1.18
+
+package stdoutmetric // import "go.opentelemetry.io/otel/exporters/stdout/stdoutmetric"
+
+import (
+	"context"
+	"sync"
+	"sync/atomic"
+
+	"go.opentelemetry.io/otel/sdk/metric"
+	"go.opentelemetry.io/otel/sdk/metric/metricdata"
+)
+
+// exporter is an OpenTelemetry metric exporter.
+type exporter struct {
+	encVal atomic.Value // encoderHolder
+
+	shutdownOnce sync.Once
+}
+
+// New returns a configured metric Exporter.
+//
+// If no options are passed, the default exporter returned will use a JSON
+// encoder with tab indentations.
+func New(options ...Option) (metric.Exporter, error) {
+	cfg, err := newConfig(options...)
+	if err != nil {
+		return nil, err
+	}
+
+	exp := &exporter{}
+	exp.encVal.Store(*cfg.encoder)
+	return exp, nil
+}
+
+func (e *exporter) Export(ctx context.Context, data metricdata.ResourceMetrics) error {
+	select {
+	case <-ctx.Done():
+		// Don't do anything if the context has already timed out.
+		return ctx.Err()
+	default:
+		// Context is still valid, continue.
+	}
+
+	return e.encVal.Load().(encoderHolder).Encode(data)
+}
+
+func (e *exporter) ForceFlush(context.Context) error {
+	// exporter holds no state, nothing to flush.
+	return nil
+}
+
+func (e *exporter) Shutdown(context.Context) error {
+	e.shutdownOnce.Do(func() {
+		e.encVal.Store(encoderHolder{
+			encoder: shutdownEncoder{},
+		})
+	})
+	return nil
+}
diff --git a/exporters/stdout/stdoutmetric/go.mod b/exporters/stdout/stdoutmetric/go.mod
new file mode 100644
index 00000000000..b6940a6db45
--- /dev/null
+++ b/exporters/stdout/stdoutmetric/go.mod
@@ -0,0 +1,27 @@
+module go.opentelemetry.io/otel/exporters/stdout/stdoutmetric
+
+go 1.18
+
+require (
+	go.opentelemetry.io/otel v1.7.0
+	go.opentelemetry.io/otel/sdk v0.0.0-00010101000000-000000000000
+	go.opentelemetry.io/otel/sdk/metric v0.0.0-00010101000000-000000000000
+)
+
+require (
+	github.com/go-logr/logr v1.2.3 // indirect
+	github.com/go-logr/stdr v1.2.2 // indirect
+	go.opentelemetry.io/otel/metric v0.0.0-00010101000000-000000000000 // indirect
+	go.opentelemetry.io/otel/trace v1.7.0 // indirect
+	golang.org/x/sys v0.0.0-20210423185535-09eb48e85fd7 // indirect
+)
+
+replace go.opentelemetry.io/otel/metric => ../../../metric
+
+replace go.opentelemetry.io/otel => ../../..
+
+replace go.opentelemetry.io/otel/sdk/metric => ../../../sdk/metric
+
+replace go.opentelemetry.io/otel/trace => ../../../trace
+
+replace go.opentelemetry.io/otel/sdk => ../../../sdk
diff --git a/exporters/stdout/stdoutmetric/go.sum b/exporters/stdout/stdoutmetric/go.sum
new file mode 100644
index 00000000000..2af466654a5
--- /dev/null
+++ b/exporters/stdout/stdoutmetric/go.sum
@@ -0,0 +1,12 @@
+github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
+github.com/go-logr/logr v1.2.2/go.mod h1:jdQByPbusPIv2/zmleS9BjJVeZ6kBagPoEUsqbVz/1A=
+github.com/go-logr/logr v1.2.3 h1:2DntVwHkVopvECVRSlL5PSo9eG+cAkDCuckLubN+rq0=
+github.com/go-logr/logr v1.2.3/go.mod h1:jdQByPbusPIv2/zmleS9BjJVeZ6kBagPoEUsqbVz/1A=
+github.com/go-logr/stdr v1.2.2 h1:hSWxHoqTgW2S2qGc0LTAI563KZ5YKYRhT3MFKZMbjag=
+github.com/go-logr/stdr v1.2.2/go.mod h1:mMo/vtBO5dYbehREoey6XUKy/eSumjCCveDpRre4VKE=
+github.com/google/go-cmp v0.5.8 h1:e6P7q2lk1O+qJJb4BtCQXlK8vWEO8V1ZeuEdJNOqZyg=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/stretchr/testify v1.7.1 h1:5TQK59W5E3v0r2duFAb7P95B6hEeOyEnHRa8MjYSMTY=
+golang.org/x/sys v0.0.0-20210423185535-09eb48e85fd7 h1:iGu644GcxtEcrInvDsQRCwJjtCIOlT2V7IRt6ah2Whw=
+golang.org/x/sys v0.0.0-20210423185535-09eb48e85fd7/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
diff --git a/sdk/instrumentation/scope.go b/sdk/instrumentation/scope.go
index 775de40e30c..bbbed01c5b3 100644
--- a/sdk/instrumentation/scope.go
+++ b/sdk/instrumentation/scope.go
@@ -29,5 +29,5 @@ type Scope struct {
 	// Version is the version of the instrumentation scope.
 	Version string
 	// SchemaURL of the telemetry emitted by the scope.
-	SchemaURL string
+	SchemaURL string `json:",omitempty"`
 }
diff --git a/sdk/metric/metricdata/data.go b/sdk/metric/metricdata/data.go
index b770b702346..f02adbbdf71 100644
--- a/sdk/metric/metricdata/data.go
+++ b/sdk/metric/metricdata/data.go
@@ -91,9 +91,9 @@ type DataPoint[N int64 | float64] struct {
 	// timeseries.
 	Attributes attribute.Set
 	// StartTime is when the timeseries was started. (optional)
-	StartTime time.Time
+	StartTime time.Time `json:",omitempty"`
 	// Time is the time when the timeseries was recorded. (optional)
-	Time time.Time
+	Time time.Time `json:",omitempty"`
 	// Value is the value of this data point.
 	Value N
 }
@@ -128,9 +128,9 @@ type HistogramDataPoint struct {
 	BucketCounts []uint64
 
 	// Min is the minimum value recorded. (optional)
-	Min *float64
+	Min *float64 `json:",omitempty"`
 	// Max is the maximum value recorded. (optional)
-	Max *float64
+	Max *float64 `json:",omitempty"`
 	// Sum is the sum of the values recorded.
 	Sum float64
 }
diff --git a/sdk/metric/metricdata/temporality.go b/sdk/metric/metricdata/temporality.go
index 561fdab50c3..f058bac1aad 100644
--- a/sdk/metric/metricdata/temporality.go
+++ b/sdk/metric/metricdata/temporality.go
@@ -35,3 +35,18 @@ const (
 	// from other cycles do not affect them.
 	DeltaTemporality
 )
+
+var temporalityString = map[Temporality]string{
+	CumulativeTemporality: "cumulative",
+	DeltaTemporality:      "delta",
+}
+
+// String returns the string name of t.
+func (t Temporality) String() string {
+	return temporalityString[t]
+}
+
+// MarshalText returns the byte encoded of t.
+func (t Temporality) MarshalText() ([]byte, error) {
+	return []byte(temporalityString[t]), nil
+}

From 406fc8a1a72e1e930778d971e74225c8095174e7 Mon Sep 17 00:00:00 2001
From: Tyler Yahn <codingalias@gmail.com>
Date: Tue, 2 Aug 2022 11:11:55 -0700
Subject: [PATCH 02/20] Use stringer to generate String for Temporality

---
 sdk/metric/metricdata/temporality.go        | 13 ++---------
 sdk/metric/metricdata/temporality_string.go | 25 +++++++++++++++++++++
 2 files changed, 27 insertions(+), 11 deletions(-)
 create mode 100644 sdk/metric/metricdata/temporality_string.go

diff --git a/sdk/metric/metricdata/temporality.go b/sdk/metric/metricdata/temporality.go
index f058bac1aad..5cf105b7947 100644
--- a/sdk/metric/metricdata/temporality.go
+++ b/sdk/metric/metricdata/temporality.go
@@ -12,6 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+//go:generate stringer -type=Temporality
 //go:build go1.17
 // +build go1.17
 
@@ -36,17 +37,7 @@ const (
 	DeltaTemporality
 )
 
-var temporalityString = map[Temporality]string{
-	CumulativeTemporality: "cumulative",
-	DeltaTemporality:      "delta",
-}
-
-// String returns the string name of t.
-func (t Temporality) String() string {
-	return temporalityString[t]
-}
-
 // MarshalText returns the byte encoded of t.
 func (t Temporality) MarshalText() ([]byte, error) {
-	return []byte(temporalityString[t]), nil
+	return []byte(t.String()), nil
 }
diff --git a/sdk/metric/metricdata/temporality_string.go b/sdk/metric/metricdata/temporality_string.go
new file mode 100644
index 00000000000..4da833cdce2
--- /dev/null
+++ b/sdk/metric/metricdata/temporality_string.go
@@ -0,0 +1,25 @@
+// Code generated by "stringer -type=Temporality"; DO NOT EDIT.
+
+package metricdata
+
+import "strconv"
+
+func _() {
+	// An "invalid array index" compiler error signifies that the constant values have changed.
+	// Re-run the stringer command to generate them again.
+	var x [1]struct{}
+	_ = x[undefinedTemporality-0]
+	_ = x[CumulativeTemporality-1]
+	_ = x[DeltaTemporality-2]
+}
+
+const _Temporality_name = "undefinedTemporalityCumulativeTemporalityDeltaTemporality"
+
+var _Temporality_index = [...]uint8{0, 20, 41, 57}
+
+func (i Temporality) String() string {
+	if i >= Temporality(len(_Temporality_index)-1) {
+		return "Temporality(" + strconv.FormatInt(int64(i), 10) + ")"
+	}
+	return _Temporality_name[_Temporality_index[i]:_Temporality_index[i+1]]
+}

From 308007d7f38589913c0e1d2dd9fe9d203513b286 Mon Sep 17 00:00:00 2001
From: Tyler Yahn <codingalias@gmail.com>
Date: Tue, 2 Aug 2022 11:12:28 -0700
Subject: [PATCH 03/20] Add vanity imports

---
 exporters/stdout/stdoutmetric/config.go  | 2 +-
 exporters/stdout/stdoutmetric/encoder.go | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/exporters/stdout/stdoutmetric/config.go b/exporters/stdout/stdoutmetric/config.go
index 04168a3867a..b18dc0b280c 100644
--- a/exporters/stdout/stdoutmetric/config.go
+++ b/exporters/stdout/stdoutmetric/config.go
@@ -15,7 +15,7 @@
 //go:build go1.18
 // +build go1.18
 
-package stdoutmetric
+package stdoutmetric // import "go.opentelemetry.io/otel/exporters/stdout/stdoutmetric"
 
 import (
 	"encoding/json"
diff --git a/exporters/stdout/stdoutmetric/encoder.go b/exporters/stdout/stdoutmetric/encoder.go
index dbfc78e493a..de397f2953e 100644
--- a/exporters/stdout/stdoutmetric/encoder.go
+++ b/exporters/stdout/stdoutmetric/encoder.go
@@ -15,7 +15,7 @@
 //go:build go1.18
 // +build go1.18
 
-package stdoutmetric
+package stdoutmetric // import "go.opentelemetry.io/otel/exporters/stdout/stdoutmetric"
 
 import "errors"
 

From d9a6180c9eeaa941cd21916100b834357e246a83 Mon Sep 17 00:00:00 2001
From: Tyler Yahn <codingalias@gmail.com>
Date: Tue, 2 Aug 2022 11:13:29 -0700
Subject: [PATCH 04/20] Update Temporality string expected output

---
 exporters/stdout/stdoutmetric/example_test.go | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/exporters/stdout/stdoutmetric/example_test.go b/exporters/stdout/stdoutmetric/example_test.go
index 7403c03c3fc..4fb2eb7d893 100644
--- a/exporters/stdout/stdoutmetric/example_test.go
+++ b/exporters/stdout/stdoutmetric/example_test.go
@@ -150,7 +150,7 @@ func Example() {
 	//                 "Value": 5
 	//               }
 	//             ],
-	//             "Temporality": "delta",
+	//             "Temporality": "DeltaTemporality",
 	//             "IsMonotonic": true
 	//           }
 	//         },
@@ -187,7 +187,7 @@ func Example() {
 	//                 "Sum": 57
 	//               }
 	//             ],
-	//             "Temporality": "delta"
+	//             "Temporality": "DeltaTemporality"
 	//           }
 	//         },
 	//         {

From 949a0aad1dc70e8070706b01ff16bbbfd0ea63e8 Mon Sep 17 00:00:00 2001
From: Tyler Yahn <codingalias@gmail.com>
Date: Tue, 2 Aug 2022 11:14:46 -0700
Subject: [PATCH 05/20] Do not return error from newConfig

---
 exporters/stdout/stdoutmetric/config.go   | 5 ++---
 exporters/stdout/stdoutmetric/exporter.go | 6 +-----
 2 files changed, 3 insertions(+), 8 deletions(-)

diff --git a/exporters/stdout/stdoutmetric/config.go b/exporters/stdout/stdoutmetric/config.go
index b18dc0b280c..b044ff7993d 100644
--- a/exporters/stdout/stdoutmetric/config.go
+++ b/exporters/stdout/stdoutmetric/config.go
@@ -1,5 +1,4 @@
 // Copyright The OpenTelemetry Authors
-//
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
@@ -28,7 +27,7 @@ type config struct {
 }
 
 // newConfig creates a validated config configured with options.
-func newConfig(options ...Option) (config, error) {
+func newConfig(options ...Option) config {
 	cfg := config{}
 	for _, opt := range options {
 		cfg = opt.apply(cfg)
@@ -40,7 +39,7 @@ func newConfig(options ...Option) (config, error) {
 		cfg.encoder = &encoderHolder{encoder: enc}
 	}
 
-	return cfg, nil
+	return cfg
 }
 
 // Option sets exporter option values.
diff --git a/exporters/stdout/stdoutmetric/exporter.go b/exporters/stdout/stdoutmetric/exporter.go
index 084c887c9bb..448fd373cce 100644
--- a/exporters/stdout/stdoutmetric/exporter.go
+++ b/exporters/stdout/stdoutmetric/exporter.go
@@ -38,11 +38,7 @@ type exporter struct {
 // If no options are passed, the default exporter returned will use a JSON
 // encoder with tab indentations.
 func New(options ...Option) (metric.Exporter, error) {
-	cfg, err := newConfig(options...)
-	if err != nil {
-		return nil, err
-	}
-
+	cfg := newConfig(options...)
 	exp := &exporter{}
 	exp.encVal.Store(*cfg.encoder)
 	return exp, nil

From e0ffcd5dbb07371c3cbc4d58528f5f921ab52714 Mon Sep 17 00:00:00 2001
From: Aaron Clawson <3766680+MadVikingGod@users.noreply.github.com>
Date: Tue, 2 Aug 2022 15:14:48 +0000
Subject: [PATCH 06/20] Add shutdown unit tests

---
 exporters/stdout/stdoutmetric/exporter.go     |  8 +--
 .../stdout/stdoutmetric/exporter_test.go      | 68 +++++++++++++++++++
 exporters/stdout/stdoutmetric/go.mod          |  6 +-
 exporters/stdout/stdoutmetric/go.sum          |  7 ++
 4 files changed, 84 insertions(+), 5 deletions(-)
 create mode 100644 exporters/stdout/stdoutmetric/exporter_test.go

diff --git a/exporters/stdout/stdoutmetric/exporter.go b/exporters/stdout/stdoutmetric/exporter.go
index 448fd373cce..c72fef6c39c 100644
--- a/exporters/stdout/stdoutmetric/exporter.go
+++ b/exporters/stdout/stdoutmetric/exporter.go
@@ -56,16 +56,16 @@ func (e *exporter) Export(ctx context.Context, data metricdata.ResourceMetrics)
 	return e.encVal.Load().(encoderHolder).Encode(data)
 }
 
-func (e *exporter) ForceFlush(context.Context) error {
+func (e *exporter) ForceFlush(ctx context.Context) error {
 	// exporter holds no state, nothing to flush.
-	return nil
+	return ctx.Err()
 }
 
-func (e *exporter) Shutdown(context.Context) error {
+func (e *exporter) Shutdown(ctx context.Context) error {
 	e.shutdownOnce.Do(func() {
 		e.encVal.Store(encoderHolder{
 			encoder: shutdownEncoder{},
 		})
 	})
-	return nil
+	return ctx.Err()
 }
diff --git a/exporters/stdout/stdoutmetric/exporter_test.go b/exporters/stdout/stdoutmetric/exporter_test.go
new file mode 100644
index 00000000000..43128899ecd
--- /dev/null
+++ b/exporters/stdout/stdoutmetric/exporter_test.go
@@ -0,0 +1,68 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build go1.18
+// +build go1.18
+
+package stdoutmetric // import "go.opentelemetry.io/otel/exporters/stdout/stdoutmetric"
+
+import (
+	"context"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestExporterShutdownHonorsTimeout(t *testing.T) {
+	ctx, cancel := context.WithTimeout(context.Background(), 1*time.Minute)
+	defer cancel()
+
+	e, err := New()
+	if err != nil {
+		t.Fatalf("failed to create exporter: %v", err)
+	}
+
+	innerCtx, innerCancel := context.WithTimeout(ctx, time.Nanosecond)
+	defer innerCancel()
+	<-innerCtx.Done()
+	err = e.Shutdown(innerCtx)
+	assert.ErrorIs(t, err, context.DeadlineExceeded)
+}
+
+func TestExporterShutdownHonorsCancel(t *testing.T) {
+	ctx, cancel := context.WithTimeout(context.Background(), 1*time.Minute)
+	defer cancel()
+
+	e, err := New()
+	if err != nil {
+		t.Fatalf("failed to create exporter: %v", err)
+	}
+
+	innerCtx, innerCancel := context.WithCancel(ctx)
+	innerCancel()
+	err = e.Shutdown(innerCtx)
+	assert.ErrorIs(t, err, context.Canceled)
+}
+
+func TestExporterShutdownNoError(t *testing.T) {
+	e, err := New()
+	if err != nil {
+		t.Fatalf("failed to create exporter: %v", err)
+	}
+
+	if err := e.Shutdown(context.Background()); err != nil {
+		t.Errorf("shutdown errored: expected nil, got %v", err)
+	}
+}
diff --git a/exporters/stdout/stdoutmetric/go.mod b/exporters/stdout/stdoutmetric/go.mod
index b6940a6db45..7795f9d53e5 100644
--- a/exporters/stdout/stdoutmetric/go.mod
+++ b/exporters/stdout/stdoutmetric/go.mod
@@ -3,17 +3,21 @@ module go.opentelemetry.io/otel/exporters/stdout/stdoutmetric
 go 1.18
 
 require (
+	github.com/stretchr/testify v1.7.1
 	go.opentelemetry.io/otel v1.7.0
+	go.opentelemetry.io/otel/metric v0.0.0-00010101000000-000000000000
 	go.opentelemetry.io/otel/sdk v0.0.0-00010101000000-000000000000
 	go.opentelemetry.io/otel/sdk/metric v0.0.0-00010101000000-000000000000
 )
 
 require (
+	github.com/davecgh/go-spew v1.1.0 // indirect
 	github.com/go-logr/logr v1.2.3 // indirect
 	github.com/go-logr/stdr v1.2.2 // indirect
-	go.opentelemetry.io/otel/metric v0.0.0-00010101000000-000000000000 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
 	go.opentelemetry.io/otel/trace v1.7.0 // indirect
 	golang.org/x/sys v0.0.0-20210423185535-09eb48e85fd7 // indirect
+	gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c // indirect
 )
 
 replace go.opentelemetry.io/otel/metric => ../../../metric
diff --git a/exporters/stdout/stdoutmetric/go.sum b/exporters/stdout/stdoutmetric/go.sum
index 2af466654a5..2e2aed63d24 100644
--- a/exporters/stdout/stdoutmetric/go.sum
+++ b/exporters/stdout/stdoutmetric/go.sum
@@ -1,4 +1,5 @@
 github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/go-logr/logr v1.2.2/go.mod h1:jdQByPbusPIv2/zmleS9BjJVeZ6kBagPoEUsqbVz/1A=
 github.com/go-logr/logr v1.2.3 h1:2DntVwHkVopvECVRSlL5PSo9eG+cAkDCuckLubN+rq0=
 github.com/go-logr/logr v1.2.3/go.mod h1:jdQByPbusPIv2/zmleS9BjJVeZ6kBagPoEUsqbVz/1A=
@@ -6,7 +7,13 @@ github.com/go-logr/stdr v1.2.2 h1:hSWxHoqTgW2S2qGc0LTAI563KZ5YKYRhT3MFKZMbjag=
 github.com/go-logr/stdr v1.2.2/go.mod h1:mMo/vtBO5dYbehREoey6XUKy/eSumjCCveDpRre4VKE=
 github.com/google/go-cmp v0.5.8 h1:e6P7q2lk1O+qJJb4BtCQXlK8vWEO8V1ZeuEdJNOqZyg=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/testify v1.7.1 h1:5TQK59W5E3v0r2duFAb7P95B6hEeOyEnHRa8MjYSMTY=
+github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 golang.org/x/sys v0.0.0-20210423185535-09eb48e85fd7 h1:iGu644GcxtEcrInvDsQRCwJjtCIOlT2V7IRt6ah2Whw=
 golang.org/x/sys v0.0.0-20210423185535-09eb48e85fd7/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

From 949cf28367e99698beb8a94fe4603a29f750254f Mon Sep 17 00:00:00 2001
From: Tyler Yahn <codingalias@gmail.com>
Date: Tue, 2 Aug 2022 11:24:16 -0700
Subject: [PATCH 07/20] Fix spelling error

---
 exporters/stdout/stdoutmetric/config.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/exporters/stdout/stdoutmetric/config.go b/exporters/stdout/stdoutmetric/config.go
index b044ff7993d..63ba9fc592e 100644
--- a/exporters/stdout/stdoutmetric/config.go
+++ b/exporters/stdout/stdoutmetric/config.go
@@ -53,7 +53,7 @@ func (o optionFunc) apply(c config) config {
 	return o(c)
 }
 
-// WithEncoder sets the exporter to use ecoder to encode all the metric
+// WithEncoder sets the exporter to use encoder to encode all the metric
 // data-types to an output.
 func WithEncoder(encoder Encoder) Option {
 	return optionFunc(func(c config) config {

From ad8785f90a5e0f5e1a52946d5d9f668dfd3c4a5c Mon Sep 17 00:00:00 2001
From: Tyler Yahn <codingalias@gmail.com>
Date: Tue, 2 Aug 2022 11:40:21 -0700
Subject: [PATCH 08/20] Unify testing of ctx errors and test ForceFlush

---
 .../stdout/stdoutmetric/exporter_test.go      | 70 ++++++++++---------
 1 file changed, 37 insertions(+), 33 deletions(-)

diff --git a/exporters/stdout/stdoutmetric/exporter_test.go b/exporters/stdout/stdoutmetric/exporter_test.go
index 43128899ecd..a6562d54994 100644
--- a/exporters/stdout/stdoutmetric/exporter_test.go
+++ b/exporters/stdout/stdoutmetric/exporter_test.go
@@ -15,7 +15,7 @@
 //go:build go1.18
 // +build go1.18
 
-package stdoutmetric // import "go.opentelemetry.io/otel/exporters/stdout/stdoutmetric"
+package stdoutmetric_test // import "go.opentelemetry.io/otel/exporters/stdout/stdoutmetric"
 
 import (
 	"context"
@@ -23,46 +23,50 @@ import (
 	"time"
 
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"go.opentelemetry.io/otel/exporters/stdout/stdoutmetric"
 )
 
-func TestExporterShutdownHonorsTimeout(t *testing.T) {
-	ctx, cancel := context.WithTimeout(context.Background(), 1*time.Minute)
-	defer cancel()
+func testCtxErrHonored(factory func(*testing.T) func(context.Context) error) func(t *testing.T) {
+	return func(t *testing.T) {
+		t.Helper()
+		ctx, cancel := context.WithCancel(context.Background())
+		t.Cleanup(cancel)
 
-	e, err := New()
-	if err != nil {
-		t.Fatalf("failed to create exporter: %v", err)
-	}
+		t.Run("DeadlineExceeded", func(t *testing.T) {
+			innerCtx, innerCancel := context.WithTimeout(ctx, time.Nanosecond)
+			t.Cleanup(innerCancel)
+			<-innerCtx.Done()
 
-	innerCtx, innerCancel := context.WithTimeout(ctx, time.Nanosecond)
-	defer innerCancel()
-	<-innerCtx.Done()
-	err = e.Shutdown(innerCtx)
-	assert.ErrorIs(t, err, context.DeadlineExceeded)
-}
+			f := factory(t)
+			assert.ErrorIs(t, f(innerCtx), context.DeadlineExceeded)
+		})
 
-func TestExporterShutdownHonorsCancel(t *testing.T) {
-	ctx, cancel := context.WithTimeout(context.Background(), 1*time.Minute)
-	defer cancel()
+		t.Run("Canceled", func(t *testing.T) {
+			innerCtx, innerCancel := context.WithCancel(ctx)
+			innerCancel()
 
-	e, err := New()
-	if err != nil {
-		t.Fatalf("failed to create exporter: %v", err)
-	}
+			f := factory(t)
+			assert.ErrorIs(t, f(innerCtx), context.Canceled)
+		})
 
-	innerCtx, innerCancel := context.WithCancel(ctx)
-	innerCancel()
-	err = e.Shutdown(innerCtx)
-	assert.ErrorIs(t, err, context.Canceled)
+		t.Run("NoError", func(t *testing.T) {
+			f := factory(t)
+			assert.NoError(t, f(ctx))
+		})
+	}
 }
 
-func TestExporterShutdownNoError(t *testing.T) {
-	e, err := New()
-	if err != nil {
-		t.Fatalf("failed to create exporter: %v", err)
-	}
+func TestExporterHonorsContextErrors(t *testing.T) {
+	t.Run("Shutdown", testCtxErrHonored(func(t *testing.T) func(context.Context) error {
+		exp, err := stdoutmetric.New()
+		require.NoError(t, err)
+		return exp.Shutdown
+	}))
 
-	if err := e.Shutdown(context.Background()); err != nil {
-		t.Errorf("shutdown errored: expected nil, got %v", err)
-	}
+	t.Run("ForceFlush", testCtxErrHonored(func(t *testing.T) func(context.Context) error {
+		exp, err := stdoutmetric.New()
+		require.NoError(t, err)
+		return exp.ForceFlush
+	}))
 }

From 31f86bbac7f351d37b5f8996ba3fb473550eb347 Mon Sep 17 00:00:00 2001
From: Tyler Yahn <codingalias@gmail.com>
Date: Tue, 2 Aug 2022 11:43:43 -0700
Subject: [PATCH 09/20] Add unit test for Export handle of ctx errs

---
 exporters/stdout/stdoutmetric/exporter_test.go | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/exporters/stdout/stdoutmetric/exporter_test.go b/exporters/stdout/stdoutmetric/exporter_test.go
index a6562d54994..db4a3bc535b 100644
--- a/exporters/stdout/stdoutmetric/exporter_test.go
+++ b/exporters/stdout/stdoutmetric/exporter_test.go
@@ -25,6 +25,7 @@ import (
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 	"go.opentelemetry.io/otel/exporters/stdout/stdoutmetric"
+	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 )
 
 func testCtxErrHonored(factory func(*testing.T) func(context.Context) error) func(t *testing.T) {
@@ -69,4 +70,13 @@ func TestExporterHonorsContextErrors(t *testing.T) {
 		require.NoError(t, err)
 		return exp.ForceFlush
 	}))
+
+	t.Run("Export", testCtxErrHonored(func(t *testing.T) func(context.Context) error {
+		exp, err := stdoutmetric.New()
+		require.NoError(t, err)
+		return func(ctx context.Context) error {
+			var data metricdata.ResourceMetrics
+			return exp.Export(ctx, data)
+		}
+	}))
 }

From d4319c9da36e5a2c82ecf9cacdbe1901acf4c705 Mon Sep 17 00:00:00 2001
From: Tyler Yahn <codingalias@gmail.com>
Date: Tue, 2 Aug 2022 12:03:15 -0700
Subject: [PATCH 10/20] Clarify documentation about alt OTLP exporter

---
 exporters/stdout/stdoutmetric/doc.go | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/exporters/stdout/stdoutmetric/doc.go b/exporters/stdout/stdoutmetric/doc.go
index 4710c73f2f3..eea70f8a6fa 100644
--- a/exporters/stdout/stdoutmetric/doc.go
+++ b/exporters/stdout/stdoutmetric/doc.go
@@ -18,5 +18,6 @@
 // The exporter is intended to be used for testing and debugging. It is not an
 // exporter meant for production use. Additionally, it does not provide an
 // interchange format for OpenTelemetry that is supported with any stability
-// or compatibility guarantees. Please use the OTLP instead.
+// or compatibility guarantees. If these are needed features, please use the
+// OTLP exporter instead.
 package stdoutmetric // import "go.opentelemetry.io/otel/exporters/stdout/stdoutmetric"

From 0f82e3867d4be1dc06f3c8be83c87d108a08af03 Mon Sep 17 00:00:00 2001
From: Tyler Yahn <codingalias@gmail.com>
Date: Tue, 2 Aug 2022 12:03:36 -0700
Subject: [PATCH 11/20] Remove unused ErrUnrecognized

A third party encoder can produce their own errors. This code does
nothing unique with this error, therefore, it is removed.
---
 exporters/stdout/stdoutmetric/encoder.go | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/exporters/stdout/stdoutmetric/encoder.go b/exporters/stdout/stdoutmetric/encoder.go
index de397f2953e..b2bc34c9f13 100644
--- a/exporters/stdout/stdoutmetric/encoder.go
+++ b/exporters/stdout/stdoutmetric/encoder.go
@@ -19,16 +19,11 @@ package stdoutmetric // import "go.opentelemetry.io/otel/exporters/stdout/stdout
 
 import "errors"
 
-var ErrUnrecognized = errors.New("unrecognized metric data")
-
 // Encoder encodes and outputs OpenTelemetry metric data-types as human
 // readable text.
 type Encoder interface {
 	// Encode handles the encoding and writing OpenTelemetry metric data-types
 	// that the exporter will pass to it.
-	//
-	// Any data-type that is not recognized by the encoder and not output to
-	// the user, will have an ErrUnrecognized returned from Encode.
 	Encode(v any) error
 }
 

From 25f2f0ae646399456b1851b778d4e74e71dc9633 Mon Sep 17 00:00:00 2001
From: Tyler Yahn <codingalias@gmail.com>
Date: Tue, 2 Aug 2022 12:04:41 -0700
Subject: [PATCH 12/20] Lint exporter_test.go

---
 exporters/stdout/stdoutmetric/exporter_test.go | 1 +
 1 file changed, 1 insertion(+)

diff --git a/exporters/stdout/stdoutmetric/exporter_test.go b/exporters/stdout/stdoutmetric/exporter_test.go
index db4a3bc535b..25b26fb1587 100644
--- a/exporters/stdout/stdoutmetric/exporter_test.go
+++ b/exporters/stdout/stdoutmetric/exporter_test.go
@@ -24,6 +24,7 @@ import (
 
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
+
 	"go.opentelemetry.io/otel/exporters/stdout/stdoutmetric"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 )

From 830e97a55ad23400192e9bfb71992e0316c9f8c2 Mon Sep 17 00:00:00 2001
From: Tyler Yahn <codingalias@gmail.com>
Date: Tue, 2 Aug 2022 12:05:38 -0700
Subject: [PATCH 13/20] Refactor example_test.go removing FIXME

---
 exporters/stdout/stdoutmetric/example_test.go | 128 ++++++++++--------
 1 file changed, 72 insertions(+), 56 deletions(-)

diff --git a/exporters/stdout/stdoutmetric/example_test.go b/exporters/stdout/stdoutmetric/example_test.go
index 4fb2eb7d893..d19c3eee9c8 100644
--- a/exporters/stdout/stdoutmetric/example_test.go
+++ b/exporters/stdout/stdoutmetric/example_test.go
@@ -27,77 +27,81 @@ import (
 	"go.opentelemetry.io/otel/exporters/stdout/stdoutmetric"
 	"go.opentelemetry.io/otel/metric/unit"
 	"go.opentelemetry.io/otel/sdk/instrumentation"
+	"go.opentelemetry.io/otel/sdk/metric"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 	"go.opentelemetry.io/otel/sdk/resource"
 	semconv "go.opentelemetry.io/otel/semconv/v1.10.0"
 )
 
-// Sat Jan 01 2000 00:00:00 GMT+0000.
-var now = time.Unix(946684800, 0)
+var (
+	// Sat Jan 01 2000 00:00:00 GMT+0000.
+	now = time.Unix(946684800, 0)
 
-var mockData = metricdata.ResourceMetrics{
-	Resource: resource.NewSchemaless(semconv.ServiceNameKey.String("stdoutmetric-example")),
-	ScopeMetrics: []metricdata.ScopeMetrics{
-		{
-			Scope: instrumentation.Scope{
-				Name:    "example",
-				Version: "v0.0.1",
-			},
-			Metrics: []metricdata.Metrics{
-				{
-					Name:        "requests",
-					Description: "Number of requests received",
-					Unit:        unit.Dimensionless,
-					Data: metricdata.Sum[int64]{
-						IsMonotonic: true,
-						Temporality: metricdata.DeltaTemporality,
-						DataPoints: []metricdata.DataPoint[int64]{
-							{
-								Attributes: attribute.NewSet(attribute.String("server", "central")),
-								StartTime:  now,
-								Time:       now.Add(1 * time.Second),
-								Value:      5,
+	res = resource.NewSchemaless(
+		semconv.ServiceNameKey.String("stdoutmetric-example"),
+	)
+
+	mockData = metricdata.ResourceMetrics{
+		Resource: res,
+		ScopeMetrics: []metricdata.ScopeMetrics{
+			{
+				Scope: instrumentation.Scope{Name: "example", Version: "v0.0.1"},
+				Metrics: []metricdata.Metrics{
+					{
+						Name:        "requests",
+						Description: "Number of requests received",
+						Unit:        unit.Dimensionless,
+						Data: metricdata.Sum[int64]{
+							IsMonotonic: true,
+							Temporality: metricdata.DeltaTemporality,
+							DataPoints: []metricdata.DataPoint[int64]{
+								{
+									Attributes: attribute.NewSet(attribute.String("server", "central")),
+									StartTime:  now,
+									Time:       now.Add(1 * time.Second),
+									Value:      5,
+								},
 							},
 						},
 					},
-				},
-				{
-					Name:        "latency",
-					Description: "Time spend processing received requests",
-					Unit:        unit.Milliseconds,
-					Data: metricdata.Histogram{
-						Temporality: metricdata.DeltaTemporality,
-						DataPoints: []metricdata.HistogramDataPoint{
-							{
-								Attributes:   attribute.NewSet(attribute.String("server", "central")),
-								StartTime:    now,
-								Time:         now.Add(1 * time.Second),
-								Count:        10,
-								Bounds:       []float64{1, 5, 10},
-								BucketCounts: []uint64{1, 3, 6, 0},
-								Sum:          57,
+					{
+						Name:        "latency",
+						Description: "Time spend processing received requests",
+						Unit:        unit.Milliseconds,
+						Data: metricdata.Histogram{
+							Temporality: metricdata.DeltaTemporality,
+							DataPoints: []metricdata.HistogramDataPoint{
+								{
+									Attributes:   attribute.NewSet(attribute.String("server", "central")),
+									StartTime:    now,
+									Time:         now.Add(1 * time.Second),
+									Count:        10,
+									Bounds:       []float64{1, 5, 10},
+									BucketCounts: []uint64{1, 3, 6, 0},
+									Sum:          57,
+								},
 							},
 						},
 					},
-				},
-				{
-					Name:        "temperature",
-					Description: "CPU global temperature",
-					Unit:        unit.Unit("cel(1 K)"),
-					Data: metricdata.Gauge[float64]{
-						DataPoints: []metricdata.DataPoint[float64]{
-							{
-								Attributes: attribute.NewSet(attribute.String("server", "central")),
-								Time:       now.Add(1 * time.Second),
-								Value:      32.4,
+					{
+						Name:        "temperature",
+						Description: "CPU global temperature",
+						Unit:        unit.Unit("cel(1 K)"),
+						Data: metricdata.Gauge[float64]{
+							DataPoints: []metricdata.DataPoint[float64]{
+								{
+									Attributes: attribute.NewSet(attribute.String("server", "central")),
+									Time:       now.Add(1 * time.Second),
+									Value:      32.4,
+								},
 							},
 						},
 					},
 				},
 			},
 		},
-	},
-}
+	}
+)
 
 func Example() {
 	// Print with a JSON encoder that indents with two spaces.
@@ -107,9 +111,21 @@ func Example() {
 	if err != nil {
 		panic(err)
 	}
-	// FIXME: The exporter should be registered with an SDK and the output
-	// should come from that.
-	exp.Export(context.Background(), mockData)
+
+	// Register the exporter with an SDK via a periodic reader.
+	sdk := metric.NewMeterProvider(
+		metric.WithResource(res),
+		metric.WithReader(metric.NewPeriodicReader(exp)),
+	)
+
+	ctx := context.Background()
+	// This is where the sdk would be used to create a Meter and from that
+	// instruments that would make measurments of your code. To simulate that
+	// behavior, call export directly with mocked data.
+	_ = exp.Export(ctx, mockData)
+
+	// Ensure the periodic reader is cleaned up by shutting down the sdk.
+	sdk.Shutdown(ctx)
 
 	// Output:
 	// {

From 8e490873c757aa3b41f8c4549d8cd16351c00c0f Mon Sep 17 00:00:00 2001
From: Tyler Yahn <codingalias@gmail.com>
Date: Tue, 2 Aug 2022 12:13:08 -0700
Subject: [PATCH 14/20] Add test for Export shutdown err

---
 exporters/stdout/stdoutmetric/exporter_test.go | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/exporters/stdout/stdoutmetric/exporter_test.go b/exporters/stdout/stdoutmetric/exporter_test.go
index 25b26fb1587..bd88fd4804d 100644
--- a/exporters/stdout/stdoutmetric/exporter_test.go
+++ b/exporters/stdout/stdoutmetric/exporter_test.go
@@ -81,3 +81,14 @@ func TestExporterHonorsContextErrors(t *testing.T) {
 		}
 	}))
 }
+
+func TestShutdownExporterReturnsShutdownErrorOnExport(t *testing.T) {
+	var (
+		data     metricdata.ResourceMetrics
+		ctx      = context.Background()
+		exp, err = stdoutmetric.New()
+	)
+	require.NoError(t, err)
+	require.NoError(t, exp.Shutdown(ctx))
+	assert.EqualError(t, exp.Export(ctx, data), "exporter shutdown")
+}

From 59602ba51fb9774bc7e45bc6f24f8a321045928c Mon Sep 17 00:00:00 2001
From: Tyler Yahn <codingalias@gmail.com>
Date: Tue, 2 Aug 2022 12:30:38 -0700
Subject: [PATCH 15/20] Add a discard encoder for testing

---
 exporters/stdout/stdoutmetric/exporter_test.go | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/exporters/stdout/stdoutmetric/exporter_test.go b/exporters/stdout/stdoutmetric/exporter_test.go
index bd88fd4804d..4e55637ca40 100644
--- a/exporters/stdout/stdoutmetric/exporter_test.go
+++ b/exporters/stdout/stdoutmetric/exporter_test.go
@@ -19,6 +19,8 @@ package stdoutmetric_test // import "go.opentelemetry.io/otel/exporters/stdout/s
 
 import (
 	"context"
+	"encoding/json"
+	"io"
 	"testing"
 	"time"
 
@@ -29,6 +31,12 @@ import (
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 )
 
+func testEncoderOption(t *testing.T) stdoutmetric.Option {
+	// Discard export output for testing.
+	enc := json.NewEncoder(io.Discard)
+	return stdoutmetric.WithEncoder(enc)
+}
+
 func testCtxErrHonored(factory func(*testing.T) func(context.Context) error) func(t *testing.T) {
 	return func(t *testing.T) {
 		t.Helper()
@@ -61,19 +69,19 @@ func testCtxErrHonored(factory func(*testing.T) func(context.Context) error) fun
 
 func TestExporterHonorsContextErrors(t *testing.T) {
 	t.Run("Shutdown", testCtxErrHonored(func(t *testing.T) func(context.Context) error {
-		exp, err := stdoutmetric.New()
+		exp, err := stdoutmetric.New(testEncoderOption(t))
 		require.NoError(t, err)
 		return exp.Shutdown
 	}))
 
 	t.Run("ForceFlush", testCtxErrHonored(func(t *testing.T) func(context.Context) error {
-		exp, err := stdoutmetric.New()
+		exp, err := stdoutmetric.New(testEncoderOption(t))
 		require.NoError(t, err)
 		return exp.ForceFlush
 	}))
 
 	t.Run("Export", testCtxErrHonored(func(t *testing.T) func(context.Context) error {
-		exp, err := stdoutmetric.New()
+		exp, err := stdoutmetric.New(testEncoderOption(t))
 		require.NoError(t, err)
 		return func(ctx context.Context) error {
 			var data metricdata.ResourceMetrics
@@ -86,7 +94,7 @@ func TestShutdownExporterReturnsShutdownErrorOnExport(t *testing.T) {
 	var (
 		data     metricdata.ResourceMetrics
 		ctx      = context.Background()
-		exp, err = stdoutmetric.New()
+		exp, err = stdoutmetric.New(testEncoderOption(t))
 	)
 	require.NoError(t, err)
 	require.NoError(t, exp.Shutdown(ctx))

From 070f15980a469bf0e93f02b76f9f642e4079255c Mon Sep 17 00:00:00 2001
From: Tyler Yahn <codingalias@gmail.com>
Date: Tue, 2 Aug 2022 13:03:35 -0700
Subject: [PATCH 16/20] Acknowledged error is returned from Shutdown

---
 exporters/stdout/stdoutmetric/example_test.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/exporters/stdout/stdoutmetric/example_test.go b/exporters/stdout/stdoutmetric/example_test.go
index d19c3eee9c8..784c4dee42d 100644
--- a/exporters/stdout/stdoutmetric/example_test.go
+++ b/exporters/stdout/stdoutmetric/example_test.go
@@ -125,7 +125,7 @@ func Example() {
 	_ = exp.Export(ctx, mockData)
 
 	// Ensure the periodic reader is cleaned up by shutting down the sdk.
-	sdk.Shutdown(ctx)
+	_ = sdk.Shutdown(ctx)
 
 	// Output:
 	// {

From e25735a1e03209dceeb3c0604dc136d5445165ef Mon Sep 17 00:00:00 2001
From: Tyler Yahn <codingalias@gmail.com>
Date: Tue, 2 Aug 2022 13:04:13 -0700
Subject: [PATCH 17/20] Remove unexpected SchemaURL from stdouttrace test

---
 exporters/stdout/stdouttrace/trace_test.go | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/exporters/stdout/stdouttrace/trace_test.go b/exporters/stdout/stdouttrace/trace_test.go
index 649312bf697..8f056460cdb 100644
--- a/exporters/stdout/stdouttrace/trace_test.go
+++ b/exporters/stdout/stdouttrace/trace_test.go
@@ -185,8 +185,7 @@ func expectedJSON(now time.Time) string {
 	],
 	"InstrumentationLibrary": {
 		"Name": "",
-		"Version": "",
-		"SchemaURL": ""
+		"Version": ""
 	}
 }
 `

From 61fa5ad4ee6bec191e545c6710a5919b418ad388 Mon Sep 17 00:00:00 2001
From: Tyler Yahn <codingalias@gmail.com>
Date: Tue, 2 Aug 2022 13:09:16 -0700
Subject: [PATCH 18/20] Remove unneeded *testing.T arg from testEncoderOption

---
 exporters/stdout/stdoutmetric/exporter_test.go | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/exporters/stdout/stdoutmetric/exporter_test.go b/exporters/stdout/stdoutmetric/exporter_test.go
index 4e55637ca40..9e8faa3e8ec 100644
--- a/exporters/stdout/stdoutmetric/exporter_test.go
+++ b/exporters/stdout/stdoutmetric/exporter_test.go
@@ -31,7 +31,7 @@ import (
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 )
 
-func testEncoderOption(t *testing.T) stdoutmetric.Option {
+func testEncoderOption() stdoutmetric.Option {
 	// Discard export output for testing.
 	enc := json.NewEncoder(io.Discard)
 	return stdoutmetric.WithEncoder(enc)
@@ -69,19 +69,19 @@ func testCtxErrHonored(factory func(*testing.T) func(context.Context) error) fun
 
 func TestExporterHonorsContextErrors(t *testing.T) {
 	t.Run("Shutdown", testCtxErrHonored(func(t *testing.T) func(context.Context) error {
-		exp, err := stdoutmetric.New(testEncoderOption(t))
+		exp, err := stdoutmetric.New(testEncoderOption())
 		require.NoError(t, err)
 		return exp.Shutdown
 	}))
 
 	t.Run("ForceFlush", testCtxErrHonored(func(t *testing.T) func(context.Context) error {
-		exp, err := stdoutmetric.New(testEncoderOption(t))
+		exp, err := stdoutmetric.New(testEncoderOption())
 		require.NoError(t, err)
 		return exp.ForceFlush
 	}))
 
 	t.Run("Export", testCtxErrHonored(func(t *testing.T) func(context.Context) error {
-		exp, err := stdoutmetric.New(testEncoderOption(t))
+		exp, err := stdoutmetric.New(testEncoderOption())
 		require.NoError(t, err)
 		return func(ctx context.Context) error {
 			var data metricdata.ResourceMetrics
@@ -94,7 +94,7 @@ func TestShutdownExporterReturnsShutdownErrorOnExport(t *testing.T) {
 	var (
 		data     metricdata.ResourceMetrics
 		ctx      = context.Background()
-		exp, err = stdoutmetric.New(testEncoderOption(t))
+		exp, err = stdoutmetric.New(testEncoderOption())
 	)
 	require.NoError(t, err)
 	require.NoError(t, exp.Shutdown(ctx))

From e2926a093053ac217beb84882219abe6a51ffd23 Mon Sep 17 00:00:00 2001
From: Tyler Yahn <codingalias@gmail.com>
Date: Tue, 2 Aug 2022 14:27:45 -0700
Subject: [PATCH 19/20] Fix the location of now

---
 exporters/stdout/stdoutmetric/example_test.go | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/exporters/stdout/stdoutmetric/example_test.go b/exporters/stdout/stdoutmetric/example_test.go
index 784c4dee42d..8a2528661dd 100644
--- a/exporters/stdout/stdoutmetric/example_test.go
+++ b/exporters/stdout/stdoutmetric/example_test.go
@@ -35,7 +35,7 @@ import (
 
 var (
 	// Sat Jan 01 2000 00:00:00 GMT+0000.
-	now = time.Unix(946684800, 0)
+	now = time.Date(2000, time.January, 01, 0, 0, 0, 0, time.FixedZone("GMT", 0))
 
 	res = resource.NewSchemaless(
 		semconv.ServiceNameKey.String("stdoutmetric-example"),
@@ -161,8 +161,8 @@ func Example() {
 	//                     }
 	//                   }
 	//                 ],
-	//                 "StartTime": "1999-12-31T16:00:00-08:00",
-	//                 "Time": "1999-12-31T16:00:01-08:00",
+	//                 "StartTime": "2000-01-01T00:00:00Z",
+	//                 "Time": "2000-01-01T00:00:01Z",
 	//                 "Value": 5
 	//               }
 	//             ],
@@ -186,8 +186,8 @@ func Example() {
 	//                     }
 	//                   }
 	//                 ],
-	//                 "StartTime": "1999-12-31T16:00:00-08:00",
-	//                 "Time": "1999-12-31T16:00:01-08:00",
+	//                 "StartTime": "2000-01-01T00:00:00Z",
+	//                 "Time": "2000-01-01T00:00:01Z",
 	//                 "Count": 10,
 	//                 "Bounds": [
 	//                   1,
@@ -223,7 +223,7 @@ func Example() {
 	//                   }
 	//                 ],
 	//                 "StartTime": "0001-01-01T00:00:00Z",
-	//                 "Time": "1999-12-31T16:00:01-08:00",
+	//                 "Time": "2000-01-01T00:00:01Z",
 	//                 "Value": 32.4
 	//               }
 	//             ]

From 54a3e2489a6666c3c368b9aebc373594b94425ef Mon Sep 17 00:00:00 2001
From: Tyler Yahn <codingalias@gmail.com>
Date: Tue, 2 Aug 2022 14:41:22 -0700
Subject: [PATCH 20/20] Revise and edit docs

---
 exporters/stdout/stdoutmetric/doc.go      | 10 +++++-----
 exporters/stdout/stdoutmetric/encoder.go  |  3 +--
 exporters/stdout/stdoutmetric/exporter.go |  4 ++--
 3 files changed, 8 insertions(+), 9 deletions(-)

diff --git a/exporters/stdout/stdoutmetric/doc.go b/exporters/stdout/stdoutmetric/doc.go
index eea70f8a6fa..fc766ad0bea 100644
--- a/exporters/stdout/stdoutmetric/doc.go
+++ b/exporters/stdout/stdoutmetric/doc.go
@@ -15,9 +15,9 @@
 // Package stdoutmetric provides an exporter for OpenTelemetry metric
 // telemetry.
 //
-// The exporter is intended to be used for testing and debugging. It is not an
-// exporter meant for production use. Additionally, it does not provide an
-// interchange format for OpenTelemetry that is supported with any stability
-// or compatibility guarantees. If these are needed features, please use the
-// OTLP exporter instead.
+// The exporter is intended to be used for testing and debugging, it is not
+// meant for production use. Additionally, it does not provide an interchange
+// format for OpenTelemetry that is supported with any stability or
+// compatibility guarantees. If these are needed features, please use the OTLP
+// exporter instead.
 package stdoutmetric // import "go.opentelemetry.io/otel/exporters/stdout/stdoutmetric"
diff --git a/exporters/stdout/stdoutmetric/encoder.go b/exporters/stdout/stdoutmetric/encoder.go
index b2bc34c9f13..ab5510afcbe 100644
--- a/exporters/stdout/stdoutmetric/encoder.go
+++ b/exporters/stdout/stdoutmetric/encoder.go
@@ -22,8 +22,7 @@ import "errors"
 // Encoder encodes and outputs OpenTelemetry metric data-types as human
 // readable text.
 type Encoder interface {
-	// Encode handles the encoding and writing OpenTelemetry metric data-types
-	// that the exporter will pass to it.
+	// Encode handles the encoding and writing of OpenTelemetry metric data.
 	Encode(v any) error
 }
 
diff --git a/exporters/stdout/stdoutmetric/exporter.go b/exporters/stdout/stdoutmetric/exporter.go
index c72fef6c39c..f7976d5993f 100644
--- a/exporters/stdout/stdoutmetric/exporter.go
+++ b/exporters/stdout/stdoutmetric/exporter.go
@@ -33,10 +33,10 @@ type exporter struct {
 	shutdownOnce sync.Once
 }
 
-// New returns a configured metric Exporter.
+// New returns a configured metric exporter.
 //
 // If no options are passed, the default exporter returned will use a JSON
-// encoder with tab indentations.
+// encoder with tab indentations that output to STDOUT.
 func New(options ...Option) (metric.Exporter, error) {
 	cfg := newConfig(options...)
 	exp := &exporter{}