Update tests to use cmp.Diff instead of reflect.DeepEqual

language/go/BUILD.bazel

@@ -61,6 +61,7 @@ go_test(
         "generate_test.go",
         "resolve_test.go",
         "stubs_test.go",
+        "testutils_test.go",
         "update_import_test.go",
     ],
     data = glob(["testdata/**"]),
@@ -78,6 +79,7 @@ go_test(
         "//testtools",
         "//walk",
         "@com_github_bazelbuild_buildtools//build:go_default_library",
+        "@com_github_google_go_cmp//cmp",
         "@org_golang_x_tools//go/vcs",
     ],
 )

language/go/config_test.go

@@ -18,7 +18,6 @@ package golang
 import (
 	"path"
 	"path/filepath"
-	"reflect"
 	"strings"
 	"testing"
 
@@ -121,14 +120,15 @@ func TestDirectives(t *testing.T) {
 	if !gc.goGrpcCompilersSet {
 		t.Error("expected goGrpcCompilersSet to be set")
 	}
-	if !reflect.DeepEqual(gc.goGrpcCompilers, []string{"abc", "def"}) {
-		t.Errorf("got goGrpcCompilers %v; want [abc def]", gc.goGrpcCompilers)
+	if diff := cmpDiff([]string{"abc", "def"}, gc.goGrpcCompilers); diff != "" {
+		t.Errorf("(-want, +got): %s", diff)
 	}
+
 	if !gc.goProtoCompilersSet {
 		t.Error("expected goProtoCompilersSet to be set")
 	}
-	if !reflect.DeepEqual(gc.goProtoCompilers, []string{"foo", "bar"}) {
-		t.Errorf("got goProtoCompilers %v; want [foo bar]", gc.goProtoCompilers)
+	if diff := cmpDiff(gc.goProtoCompilers, []string{"foo", "bar"}); diff != "" {
+		t.Errorf("(-want, +got): %s", diff)
 	}
 
 	subContent := []byte(`
@@ -146,15 +146,17 @@ func TestDirectives(t *testing.T) {
 	if gc.goGrpcCompilersSet {
 		t.Error("expected goGrpcCompilersSet to be unset")
 	}
-	if !reflect.DeepEqual(gc.goGrpcCompilers, defaultGoGrpcCompilers) {
-		t.Errorf("got goGrpcCompilers %v; want %v", gc.goGrpcCompilers, defaultGoGrpcCompilers)
+	if diff := cmpDiff(defaultGoGrpcCompilers, gc.goGrpcCompilers); diff != "" {
+		t.Errorf("(-want, +got): %s", diff)
 	}
+
 	if gc.goProtoCompilersSet {
 		t.Error("expected goProtoCompilersSet to be unset")
 	}
-	if !reflect.DeepEqual(gc.goProtoCompilers, defaultGoProtoCompilers) {
-		t.Errorf("got goProtoCompilers %v; want %v", gc.goProtoCompilers, defaultGoProtoCompilers)
+	if diff := cmpDiff(defaultGoProtoCompilers, gc.goProtoCompilers); diff != "" {
+		t.Errorf("(-want, +got): %s", diff)
 	}
+
 }
 
 func TestVendorConfig(t *testing.T) {
@@ -340,8 +342,9 @@ func TestSplitValue(t *testing.T) {
 		},
 	} {
 		parts := splitValue(tc.value)
-		if !reflect.DeepEqual(tc.parts, parts) {
-			t.Errorf("want %v; got %v", tc.parts, parts)
+		if diff := cmpDiff(tc.parts, parts); diff != "" {
+			t.Errorf("(-want, +got): %s", diff)
 		}
+
 	}
 }

language/go/fileinfo_go_test.go

@@ -19,7 +19,6 @@ import (
 	"io/ioutil"
 	"os"
 	"path/filepath"
-	"reflect"
 	"strings"
 	"testing"
 )
@@ -178,9 +177,10 @@ var src string
 				got.embeds[i] = fileEmbed{path: got.embeds[i].path}
 			}
 
-			if !reflect.DeepEqual(got, tc.want) {
-				t.Errorf("case %q: got %#v; want %#v", tc.desc, got, tc.want)
+			if diff := cmpDiff(tc.want, got); diff != "" {
+				t.Errorf("(-want, +got): %s", diff)
 			}
+
 		})
 	}
 }
@@ -205,9 +205,10 @@ func TestGoFileInfoFailure(t *testing.T) {
 		goos:   "linux",
 		goarch: "amd64",
 	}
-	if !reflect.DeepEqual(got, want) {
-		t.Errorf("got %#v ; want %#v", got, want)
+	if diff := cmpDiff(want, got); diff != "" {
+		t.Errorf("(-want, +got): %s", diff)
 	}
+
 }
 
 func TestCgo(t *testing.T) {
@@ -331,9 +332,10 @@ import ("C")
 				clinkopts: got.clinkopts,
 			}
 
-			if !reflect.DeepEqual(got, tc.want) {
-				t.Errorf("case %q: got %#v; want %#v", tc.desc, got, tc.want)
+			if diff := cmpDiff(tc.want, got); diff != "" {
+				t.Errorf("(-want, +got): %s", diff)
 			}
+
 		})
 	}
 }
@@ -409,9 +411,10 @@ import "C"
 	}
 	want.library.sources.addGenericString("sub.go")
 	want.library.copts.addGenericString("-Isub/..")
-	if !reflect.DeepEqual(got, want) {
-		t.Errorf("got %#v ; want %#v", got, want)
+	if diff := cmpDiff(want, got); diff != "" {
+		t.Errorf("(-want, +got): %s", diff)
 	}
+
 }
 
 // Copied from go/build build_test.go

language/go/fileinfo_test.go

@@ -55,9 +55,10 @@ func TestOtherFileInfo(t *testing.T) {
 
 			// Only check that we can extract tags. Everything else is covered
 			// by other tests.
-			if !reflect.DeepEqual(got.tags, tc.wantTags) {
-				t.Errorf("got %#v; want %#v", got.tags, tc.wantTags)
+			if diff := cmpDiff(tc.wantTags, got.tags); diff != "" {
+				t.Errorf("(-want, +got): %s", diff)
 			}
+
 		})
 	}
 }
@@ -331,8 +332,8 @@ package main`,
 
 		if got, err := readTags(path); err != nil {
 			t.Fatal(err)
-		} else if !reflect.DeepEqual(got, tc.want) {
-			t.Errorf("case %q: got %#v; want %#v", tc.desc, got, tc.want)
+		} else if diff := cmpDiff(tc.want, got); diff != "" {
+			t.Errorf("(-want, +got): %s", diff)
 		}
 	}
 }

language/go/testutils_test.go

@@ -0,0 +1,31 @@
+/* Copyright 2017 The Bazel Authors. All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+   http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package golang
+
+import (
+	"reflect"
+
+	"github.com/google/go-cmp/cmp"
+)
+
+// cmpDiff provides a diff func that can be used on any type. By default,
+// cmp.Diff will only compare exported fields. However, in order to make
+// testing un-exported types easier, this function will allow comparison
+// for any unexported type.
+func cmpDiff(want, got interface{}) string {
+	allTypes := func(_ reflect.Type) bool { return true }
+	return cmp.Diff(want, got, cmp.Exporter(allTypes))
+}