1 files changed, 191 insertions, 0 deletions
diff --git a/src/go/doc/example_test.go b/src/go/doc/example_test.go
new file mode 100644
index 000000000..e154ea8bf
--- /dev/null
+++ b/src/go/doc/example_test.go
@@ -0,0 +1,191 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package doc_test
+
+import (
+	"bytes"
+	"go/doc"
+	"go/format"
+	"go/parser"
+	"go/token"
+	"strings"
+	"testing"
+)
+
+const exampleTestFile = `
+package foo_test
+
+import (
+	"flag"
+	"fmt"
+	"log"
+	"os/exec"
+)
+
+func ExampleHello() {
+	fmt.Println("Hello, world!")
+	// Output: Hello, world!
+}
+
+func ExampleImport() {
+	out, err := exec.Command("date").Output()
+	if err != nil {
+		log.Fatal(err)
+	}
+	fmt.Printf("The date is %s\n", out)
+}
+
+func ExampleKeyValue() {
+	v := struct {
+		a string
+		b int
+	}{
+		a: "A",
+		b: 1,
+	}
+	fmt.Print(v)
+	// Output: a: "A", b: 1
+}
+
+func ExampleKeyValueImport() {
+	f := flag.Flag{
+		Name: "play",
+	}
+	fmt.Print(f)
+	// Output: Name: "play"
+}
+
+var keyValueTopDecl = struct {
+	a string
+	b int
+}{
+	a: "B",
+	b: 2,
+}
+
+func ExampleKeyValueTopDecl() {
+	fmt.Print(keyValueTopDecl)
+}
+`
+
+var exampleTestCases = []struct {
+	Name, Play, Output string
+}{
+	{
+		Name:   "Hello",
+		Play:   exampleHelloPlay,
+		Output: "Hello, world!\n",
+	},
+	{
+		Name: "Import",
+		Play: exampleImportPlay,
+	},
+	{
+		Name:   "KeyValue",
+		Play:   exampleKeyValuePlay,
+		Output: "a: \"A\", b: 1\n",
+	},
+	{
+		Name:   "KeyValueImport",
+		Play:   exampleKeyValueImportPlay,
+		Output: "Name: \"play\"\n",
+	},
+	{
+		Name: "KeyValueTopDecl",
+		Play: "<nil>",
+	},
+}
+
+const exampleHelloPlay = `package main
+
+import (
+	"fmt"
+)
+
+func main() {
+	fmt.Println("Hello, world!")
+}
+`
+const exampleImportPlay = `package main
+
+import (
+	"fmt"
+	"log"
+	"os/exec"
+)
+
+func main() {
+	out, err := exec.Command("date").Output()
+	if err != nil {
+		log.Fatal(err)
+	}
+	fmt.Printf("The date is %s\n", out)
+}
+`
+
+const exampleKeyValuePlay = `package main
+
+import (
+	"fmt"
+)
+
+func main() {
+	v := struct {
+		a string
+		b int
+	}{
+		a: "A",
+		b: 1,
+	}
+	fmt.Print(v)
+}
+`
+
+const exampleKeyValueImportPlay = `package main
+
+import (
+	"flag"
+	"fmt"
+)
+
+func main() {
+	f := flag.Flag{
+		Name: "play",
+	}
+	fmt.Print(f)
+}
+`
+
+func TestExamples(t *testing.T) {
+	fset := token.NewFileSet()
+	file, err := parser.ParseFile(fset, "test.go", strings.NewReader(exampleTestFile), parser.ParseComments)
+	if err != nil {
+		t.Fatal(err)
+	}
+	for i, e := range doc.Examples(file) {
+		c := exampleTestCases[i]
+		if e.Name != c.Name {
+			t.Errorf("got Name == %q, want %q", e.Name, c.Name)
+		}
+		if w := c.Play; w != "" {
+			var g string // hah
+			if e.Play == nil {
+				g = "<nil>"
+			} else {
+				var buf bytes.Buffer
+				if err := format.Node(&buf, fset, e.Play); err != nil {
+					t.Fatal(err)
+				}
+				g = buf.String()
+			}
+			if g != w {
+				t.Errorf("%s: got Play == %q, want %q", c.Name, g, w)
+			}
+		}
+		if g, w := e.Output, c.Output; g != w {
+			t.Errorf("%s: got Output == %q, want %q", c.Name, g, w)
+		}
+	}
+}