testing: replace CRLF by LF on windows before comparing to the expected output

Fixes #51269

Change-Id: I06747db18ca078c1f1bda9b7bc60006f53191f4d
Reviewed-on: https://go-review.googlesource.com/c/go/+/627035
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: Michael Matloob <matloob@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>

src/cmd/go/testdata/script/test_crlf_example.txt

@@ -0,0 +1,39 @@
+# Tests that crlf in the output of examples are handled.
+# Verifies golang.org/issue/51269
+go test x_test.go
+
+-- x_test.go --
+package  x
+
+import (
+    "io"
+    "fmt"
+    "os"
+    "runtime"
+)
+
+func Example_lf() {
+	fmt.Print("foo", "\n", "bar")
+	// Output:
+	// foo
+	// bar
+}
+
+func Example_println() {
+	fmt.Println("foo")
+	fmt.Println("bar")
+	// Output:
+	// foo
+	// bar
+}
+
+func Example_crlf() {
+	if runtime.GOOS == "windows" {
+		io.WriteString(os.Stdout, "foo\r\nbar\r\n")
+	} else {
+		io.WriteString(os.Stdout, "foo\nbar\n")
+	}
+	// Output:
+	// foo
+	// bar
+}

src/testing/example.go

@@ -6,6 +6,7 @@ package testing
 
 import (
 	"fmt"
+	"runtime"
 	"slices"
 	"strings"
 	"time"
@@ -66,6 +67,10 @@ func (eg *InternalExample) processRunResult(stdout string, timeSpent time.Durati
 	var fail string
 	got := strings.TrimSpace(stdout)
 	want := strings.TrimSpace(eg.Output)
+	if runtime.GOOS == "windows" {
+		got = strings.ReplaceAll(got, "\r\n", "\n")
+		want = strings.ReplaceAll(want, "\r\n", "\n")
+	}
 	if eg.Unordered {
 		if sortLines(got) != sortLines(want) && recovered == nil {
 			fail = fmt.Sprintf("got:\n%s\nwant (unordered):\n%s\n", stdout, eg.Output)