errors: move example functions into example_test file

Change-Id: Ide70476698d82a51881802dd6bf05dd7abcd60e8
GitHub-Last-Rev: ddb251ded6
GitHub-Pull-Request: golang/go#57931
Reviewed-on: https://go-review.googlesource.com/c/go/+/462292
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Auto-Submit: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Ian Lance Taylor <iant@google.com>

src/errors/errors_test.go

@@ -6,7 +6,6 @@ package errors_test
 
 import (
 	"errors"
-	"fmt"
 	"testing"
 )
 
@@ -32,40 +31,3 @@ func TestErrorMethod(t *testing.T) {
 		t.Errorf(`New("abc").Error() = %q, want %q`, err.Error(), "abc")
 	}
 }
-
-func ExampleNew() {
-	err := errors.New("emit macho dwarf: elf header corrupted")
-	if err != nil {
-		fmt.Print(err)
-	}
-	// Output: emit macho dwarf: elf header corrupted
-}
-
-// The fmt package's Errorf function lets us use the package's formatting
-// features to create descriptive error messages.
-func ExampleNew_errorf() {
-	const name, id = "bimmler", 17
-	err := fmt.Errorf("user %q (id %d) not found", name, id)
-	if err != nil {
-		fmt.Print(err)
-	}
-	// Output: user "bimmler" (id 17) not found
-}
-
-func ExampleJoin() {
-	err1 := errors.New("err1")
-	err2 := errors.New("err2")
-	err := errors.Join(err1, err2)
-	fmt.Println(err)
-	if errors.Is(err, err1) {
-		fmt.Println("err is err1")
-	}
-	if errors.Is(err, err2) {
-		fmt.Println("err is err2")
-	}
-	// Output:
-	// err1
-	// err2
-	// err is err1
-	// err is err2
-}

src/errors/example_test.go

@@ -5,7 +5,10 @@
 package errors_test
 
 import (
+	"errors"
 	"fmt"
+	"io/fs"
+	"os"
 	"time"
 )
 
@@ -32,3 +35,77 @@ func Example() {
 	}
 	// Output: 1989-03-15 22:30:00 +0000 UTC: the file system has gone away
 }
+
+func ExampleNew() {
+	err := errors.New("emit macho dwarf: elf header corrupted")
+	if err != nil {
+		fmt.Print(err)
+	}
+	// Output: emit macho dwarf: elf header corrupted
+}
+
+// The fmt package's Errorf function lets us use the package's formatting
+// features to create descriptive error messages.
+func ExampleNew_errorf() {
+	const name, id = "bimmler", 17
+	err := fmt.Errorf("user %q (id %d) not found", name, id)
+	if err != nil {
+		fmt.Print(err)
+	}
+	// Output: user "bimmler" (id 17) not found
+}
+
+func ExampleJoin() {
+	err1 := errors.New("err1")
+	err2 := errors.New("err2")
+	err := errors.Join(err1, err2)
+	fmt.Println(err)
+	if errors.Is(err, err1) {
+		fmt.Println("err is err1")
+	}
+	if errors.Is(err, err2) {
+		fmt.Println("err is err2")
+	}
+	// Output:
+	// err1
+	// err2
+	// err is err1
+	// err is err2
+}
+
+func ExampleIs() {
+	if _, err := os.Open("non-existing"); err != nil {
+		if errors.Is(err, fs.ErrNotExist) {
+			fmt.Println("file does not exist")
+		} else {
+			fmt.Println(err)
+		}
+	}
+
+	// Output:
+	// file does not exist
+}
+
+func ExampleAs() {
+	if _, err := os.Open("non-existing"); err != nil {
+		var pathError *fs.PathError
+		if errors.As(err, &pathError) {
+			fmt.Println("Failed at path:", pathError.Path)
+		} else {
+			fmt.Println(err)
+		}
+	}
+
+	// Output:
+	// Failed at path: non-existing
+}
+
+func ExampleUnwrap() {
+	err1 := errors.New("error1")
+	err2 := fmt.Errorf("error2: [%w]", err1)
+	fmt.Println(err2)
+	fmt.Println(errors.Unwrap(err2))
+	// Output
+	// error2: [error1]
+	// error1
+}

src/errors/wrap_test.go

@@ -288,40 +288,3 @@ func (errorUncomparable) Is(target error) bool {
 	_, ok := target.(errorUncomparable)
 	return ok
 }
-
-func ExampleIs() {
-	if _, err := os.Open("non-existing"); err != nil {
-		if errors.Is(err, fs.ErrNotExist) {
-			fmt.Println("file does not exist")
-		} else {
-			fmt.Println(err)
-		}
-	}
-
-	// Output:
-	// file does not exist
-}
-
-func ExampleAs() {
-	if _, err := os.Open("non-existing"); err != nil {
-		var pathError *fs.PathError
-		if errors.As(err, &pathError) {
-			fmt.Println("Failed at path:", pathError.Path)
-		} else {
-			fmt.Println(err)
-		}
-	}
-
-	// Output:
-	// Failed at path: non-existing
-}
-
-func ExampleUnwrap() {
-	err1 := errors.New("error1")
-	err2 := fmt.Errorf("error2: [%w]", err1)
-	fmt.Println(err2)
-	fmt.Println(errors.Unwrap(err2))
-	// Output
-	// error2: [error1]
-	// error1
-}