feat: add testableexamples linter (#3170)

Author: maratori

.golangci.reference.yml

@@ -2011,6 +2011,7 @@ linters:
     - stylecheck
     - tagliatelle
     - tenv
+    - testableexamples
     - testpackage
     - thelper
     - tparallel
@@ -2116,6 +2117,7 @@ linters:
     - stylecheck
     - tagliatelle
     - tenv
+    - testableexamples
     - testpackage
     - thelper
     - tparallel

go.mod

@@ -58,6 +58,7 @@ require (
 	github.com/ldez/tagliatelle v0.3.1
 	github.com/leonklingele/grouper v1.1.0
 	github.com/lufeee/execinquery v1.2.1
+	github.com/maratori/testableexamples v1.0.0
 	github.com/maratori/testpackage v1.1.0
 	github.com/matoous/godox v0.0.0-20210227103229-6504466cf951 // v1.0
 	github.com/mattn/go-colorable v0.1.13

go.sum

@@ -0,0 +1,19 @@
+package golinters
+
+import (
+	"github.com/maratori/testableexamples/pkg/testableexamples"
+	"golang.org/x/tools/go/analysis"
+
+	"github.com/golangci/golangci-lint/pkg/golinters/goanalysis"
+)
+
+func NewTestableexamples() *goanalysis.Linter {
+	a := testableexamples.NewAnalyzer()
+
+	return goanalysis.NewLinter(
+		a.Name,
+		a.Doc,
+		[]*analysis.Analyzer{a},
+		nil,
+	).WithLoadMode(goanalysis.LoadModeSyntax)
+}

pkg/golinters/testableexamples.go

@@ -750,6 +750,11 @@ func (m Manager) GetAllSupportedLinterConfigs() []*linter.Config {
 			WithLoadForGoAnalysis().
 			WithURL("https://github.com/sivchari/tenv"),
 
+		linter.NewConfig(golinters.NewTestableexamples()).
+			WithSince("v1.50.0").
+			WithPresets(linter.PresetTest).
+			WithURL("https://github.com/maratori/testableexamples"),
+
 		linter.NewConfig(golinters.NewTestpackage(testpackageCfg)).
 			WithSince("v1.25.0").
 			WithPresets(linter.PresetStyle, linter.PresetTest).

pkg/lint/lintersdb/manager.go

@@ -0,0 +1,23 @@
+//golangcitest:args -Etestableexamples
+package testdata
+
+import "fmt"
+
+func Example_good() {
+	fmt.Println("hello")
+	// Output: hello
+}
+
+func Example_goodEmptyOutput() {
+	fmt.Println("")
+	// Output:
+}
+
+func Example_bad() { // want `^missing output for example, go test can't validate it$`
+	fmt.Println("hello")
+}
+
+//nolint:testableexamples
+func Example_nolint() {
+	fmt.Println("hello")
+}