godoc: run TestStructField for Go 1.7 and up only (fix build)

There's no testing.T.Run method in Go 1.6.

Change-Id: I0ed7bdbe91d4cc4406ad5626dbae9acc42b4853a
Reviewed-on: https://go-review.googlesource.com/36119
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

godoc/godoc17_test.go

@@ -0,0 +1,35 @@
+// Copyright 2017 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.
+
+// +build go1.7
+
+package godoc
+
+import (
+	"bytes"
+	"fmt"
+	"testing"
+)
+
+// Verify that scanIdentifier isn't quadratic.
+// This doesn't actually measure and fail on its own, but it was previously
+// very obvious when running by hand.
+//
+// TODO: if there's a reliable and non-flaky way to test this, do so.
+// Maybe count user CPU time instead of wall time? But that's not easy
+// to do portably in Go.
+func TestStructField(t *testing.T) {
+	for _, n := range []int{10, 100, 1000, 10000} {
+		n := n
+		t.Run(fmt.Sprint(n), func(t *testing.T) {
+			var buf bytes.Buffer
+			fmt.Fprintf(&buf, "package foo\n\ntype T struct {\n")
+			for i := 0; i < n; i++ {
+				fmt.Fprintf(&buf, "\t// Field%d is foo.\n\tField%d int\n\n", i, i)
+			}
+			fmt.Fprintf(&buf, "}\n")
+			linkifyStructFields(t, buf.Bytes())
+		})
+	}
+}

godoc/godoc_test.go

@@ -5,8 +5,6 @@
 package godoc
 
 import (
-	"bytes"
-	"fmt"
 	"go/ast"
 	"go/parser"
 	"go/token"
@@ -174,28 +172,6 @@ func linkifyStructFields(t *testing.T, src []byte) string {
 	return p.node_htmlFunc(pi, genDecl, true)
 }
 
-// Verify that scanIdentifier isn't quadratic.
-// This doesn't actually measure and fail on its own, but it was previously
-// very obvious when running by hand.
-//
-// TODO: if there's a reliable and non-flaky way to test this, do so.
-// Maybe count user CPU time instead of wall time? But that's not easy
-// to do portably in Go.
-func TestStructField(t *testing.T) {
-	for _, n := range []int{10, 100, 1000, 10000} {
-		n := n
-		t.Run(fmt.Sprint(n), func(t *testing.T) {
-			var buf bytes.Buffer
-			fmt.Fprintf(&buf, "package foo\n\ntype T struct {\n")
-			for i := 0; i < n; i++ {
-				fmt.Fprintf(&buf, "\t// Field%d is foo.\n\tField%d int\n\n", i, i)
-			}
-			fmt.Fprintf(&buf, "}\n")
-			linkifyStructFields(t, buf.Bytes())
-		})
-	}
-}
-
 func TestScanIdentifier(t *testing.T) {
 	tests := []struct {
 		in, want string