[mdatagen] generate goleak package test (open-telemetry#9959)

This automates the generation of package_test.go for any component that
uses mdatagen.

The following configuration can be used to skip or ignore certain funcs:

```yaml
tests:
  goleak:
    skip: true

tests:
  goleak:
    ignore:
      top:
        - "go.opencensus.io/stats/view.(*worker).start"
```

---------

Signed-off-by: Alex Boten <223565+codeboten@users.noreply.github.com>

.chloggen/codeboten_mdatagen-goleak.yaml

@@ -0,0 +1,25 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: enhancement
+
+# The name of the component, or a single word describing the area of concern, (e.g. otlpreceiver)
+component: mdatagen
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: enable goleak tests by default via mdatagen
+
+# One or more tracking issues or pull requests related to the change
+issues: [9959]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:
+
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: []

cmd/mdatagen/embeded_templates_test.go

@@ -28,6 +28,7 @@ func TestEnsureTemplatesLoaded(t *testing.T) {
 			path.Join(rootDir, "resource_test.go.tmpl"):        {},
 			path.Join(rootDir, "config.go.tmpl"):               {},
 			path.Join(rootDir, "config_test.go.tmpl"):          {},
+			path.Join(rootDir, "package_test.go.tmpl"):         {},
 			path.Join(rootDir, "readme.md.tmpl"):               {},
 			path.Join(rootDir, "status.go.tmpl"):               {},
 			path.Join(rootDir, "testdata", "config.yaml.tmpl"): {},

cmd/mdatagen/loader.go

@@ -201,11 +201,22 @@ func (a attribute) TestValue() string {
 	return ""
 }
 
+type ignore struct {
+	Top []string `mapstructure:"top"`
+	Any []string `mapstructure:"any"`
+}
+
+type goLeak struct {
+	Skip   bool   `mapstructure:"skip"`
+	Ignore ignore `mapstructure:"ignore"`
+}
+
 type tests struct {
-	Config              any  `mapstructure:"config"`
-	SkipLifecycle       bool `mapstructure:"skip_lifecycle"`
-	SkipShutdown        bool `mapstructure:"skip_shutdown"`
-	ExpectConsumerError bool `mapstructure:"expect_consumer_error"`
+	Config              any    `mapstructure:"config"`
+	SkipLifecycle       bool   `mapstructure:"skip_lifecycle"`
+	SkipShutdown        bool   `mapstructure:"skip_shutdown"`
+	GoLeak              goLeak `mapstructure:"goleak"`
+	ExpectConsumerError bool   `mapstructure:"expect_consumer_error"`
 }
 
 type metadata struct {

cmd/mdatagen/main.go

@@ -66,6 +66,10 @@ func run(ymlPath string) error {
 				filepath.Join(ymlDir, "generated_component_test.go"), md, packageName); err != nil {
 				return err
 			}
+			if err = generateFile(filepath.Join(tmplDir, "package_test.go.tmpl"),
+				filepath.Join(ymlDir, "generated_package_test.go"), md, packageName); err != nil {
+				return err
+			}
 		}
 
 		if _, err = os.Stat(filepath.Join(ymlDir, "README.md")); err == nil {

cmd/mdatagen/main_test.go

@@ -23,6 +23,8 @@ func TestRunContents(t *testing.T) {
 		wantMetricsGenerated bool
 		wantConfigGenerated  bool
 		wantStatusGenerated  bool
+		wantGoleakIgnore     bool
+		wantGoleakSkip       bool
 		wantErr              bool
 	}{
 		{
@@ -64,6 +66,16 @@ func TestRunContents(t *testing.T) {
 			yml:                 "with_tests_connector.yaml",
 			wantStatusGenerated: true,
 		},
+		{
+			yml:                 "with_goleak_ignores.yaml",
+			wantStatusGenerated: true,
+			wantGoleakIgnore:    true,
+		},
+		{
+			yml:                 "with_goleak_skip.yaml",
+			wantStatusGenerated: true,
+			wantGoleakSkip:      true,
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.yml, func(t *testing.T) {
@@ -123,6 +135,27 @@ foo
 			require.Contains(t, string(contents), "func Test")
 			_, err = parser.ParseFile(token.NewFileSet(), "", contents, parser.DeclarationErrors)
 			require.NoError(t, err)
+
+			require.FileExists(t, filepath.Join(tmpdir, "generated_package_test.go"))
+			contents, err = os.ReadFile(filepath.Join(tmpdir, "generated_package_test.go")) // nolint: gosec
+			require.NoError(t, err)
+			require.Contains(t, string(contents), "func TestMain")
+			_, err = parser.ParseFile(token.NewFileSet(), "", contents, parser.DeclarationErrors)
+			require.NoError(t, err)
+
+			if tt.wantGoleakSkip {
+				require.Contains(t, string(contents), "skipping goleak test")
+			} else {
+				require.NotContains(t, string(contents), "skipping goleak test")
+			}
+
+			if tt.wantGoleakIgnore {
+				require.Contains(t, string(contents), "IgnoreTopFunction")
+				require.Contains(t, string(contents), "IgnoreAnyFunction")
+			} else {
+				require.NotContains(t, string(contents), "IgnoreTopFunction")
+				require.NotContains(t, string(contents), "IgnoreAnyFunction")
+			}
 		})
 	}
 }

cmd/mdatagen/metadata-schema.yaml

@@ -118,3 +118,8 @@ tests:
   skip_shutdown: false # false by default
   # Whether it's expected that the Consume[Logs|Metrics|Traces] method will return an error with the given configuration.
   expect_consumer_error: true # false by default
+  goleak: # {} by default generates a package_test to enable check for leaks
+    skip: false # set to true if goleak tests should be skipped
+    ignore:
+      top: [string] # Optional: array of strings representing functions that should be ignore via IgnoreTopFunction
+      any: [string] # Optional: array of strings representing functions that should be ignore via IgnoreAnyFunction

cmd/mdatagen/templates/package_test.go.tmpl

@@ -0,0 +1,17 @@
+// Code generated by mdatagen. DO NOT EDIT.
+
+package {{ .Package }}
+
+import (
+	"testing"
+
+	"go.uber.org/goleak"
+)
+
+func TestMain(m *testing.M) {
+    {{- if .Tests.GoLeak.Skip }}
+    // skipping goleak test as per metadata.yml configuration
+    {{- else }}
+	goleak.VerifyTestMain(m {{- range $val := .Tests.GoLeak.Ignore.Top}}, goleak.IgnoreTopFunction("{{$val}}"){{end}}{{- range $val := .Tests.GoLeak.Ignore.Any}}, goleak.IgnoreAnyFunction("{{$val}}"){{end}} )
+    {{- end }}
+}

cmd/mdatagen/testdata/with_goleak_ignores.yaml

@@ -0,0 +1,14 @@
+type: foobar
+
+status:
+  class: connector
+  stability:
+    beta: [traces_to_metrics, traces_to_traces, traces_to_logs, metrics_to_logs, metrics_to_metrics, metrics_to_traces, logs_to_logs, logs_to_metrics, logs_to_traces]
+
+tests:
+  goleak:
+    ignore:
+      top:
+        - "testfunc1"
+      any:
+        - "testfunc2"

cmd/mdatagen/testdata/with_goleak_skip.yaml

@@ -0,0 +1,10 @@
+type: foobar
+
+status:
+  class: connector
+  stability:
+    beta: [traces_to_metrics, traces_to_traces, traces_to_logs, metrics_to_logs, metrics_to_metrics, metrics_to_traces, logs_to_logs, logs_to_metrics, logs_to_traces]
+
+tests:
+  goleak:
+    skip: true

exporter/nopexporter/go.mod

@@ -13,6 +13,7 @@ require (
 	go.opentelemetry.io/collector/pdata v1.5.0
 	go.opentelemetry.io/otel/metric v1.25.0
 	go.opentelemetry.io/otel/trace v1.25.0
+	go.uber.org/goleak v1.3.0
 )
 
 require (

extension/memorylimiterextension/go.mod

@@ -10,6 +10,7 @@ require (
 	go.opentelemetry.io/collector/extension v0.98.0
 	go.opentelemetry.io/otel/metric v1.25.0
 	go.opentelemetry.io/otel/trace v1.25.0
+	go.uber.org/goleak v1.3.0
 	go.uber.org/zap v1.27.0
 )
 

receiver/nopreceiver/go.mod

@@ -12,6 +12,7 @@ require (
 	go.opentelemetry.io/collector/receiver v0.98.0
 	go.opentelemetry.io/otel/metric v1.25.0
 	go.opentelemetry.io/otel/trace v1.25.0
+	go.uber.org/goleak v1.3.0
 )
 
 require (