testing: add TB, an interface common to T and B

R=golang-dev, kevlar, rsc, adg, r
CC=golang-dev
https://golang.org/cl/12962043

src/pkg/database/sql/sql_test.go

@@ -39,15 +39,7 @@ const fakeDBName = "foo"
 
 var chrisBirthday = time.Unix(123456789, 0)
 
-type testOrBench interface {
-	Fatalf(string, ...interface{})
-	Errorf(string, ...interface{})
-	Fatal(...interface{})
-	Error(...interface{})
-	Logf(string, ...interface{})
-}
-
-func newTestDB(t testOrBench, name string) *DB {
+func newTestDB(t testing.TB, name string) *DB {
 	db, err := Open("test", fakeDBName)
 	if err != nil {
 		t.Fatalf("Open: %v", err)
@@ -69,14 +61,14 @@ func newTestDB(t testOrBench, name string) *DB {
 	return db
 }
 
-func exec(t testOrBench, db *DB, query string, args ...interface{}) {
+func exec(t testing.TB, db *DB, query string, args ...interface{}) {
 	_, err := db.Exec(query, args...)
 	if err != nil {
 		t.Fatalf("Exec of %q: %v", query, err)
 	}
 }
 
-func closeDB(t testOrBench, db *DB) {
+func closeDB(t testing.TB, db *DB) {
 	if e := recover(); e != nil {
 		fmt.Printf("Panic: %v\n", e)
 		panic(e)
@@ -1061,7 +1053,7 @@ func TestStmtCloseOrder(t *testing.T) {
 	}
 }
 
-func manyConcurrentQueries(t testOrBench) {
+func manyConcurrentQueries(t testing.TB) {
 	maxProcs, numReqs := 16, 500
 	if testing.Short() {
 		maxProcs, numReqs = 4, 50

src/pkg/testing/testing.go

@@ -196,6 +196,31 @@ func decorate(s string) string {
 	return buf.String()
 }
 
+// TB is the interface common to T and B.
+type TB interface {
+	Error(args ...interface{})
+	Errorf(format string, args ...interface{})
+	Fail()
+	FailNow()
+	Failed() bool
+	Fatal(args ...interface{})
+	Fatalf(format string, args ...interface{})
+	Log(args ...interface{})
+	Logf(format string, args ...interface{})
+	Skip(args ...interface{})
+	SkipNow()
+	Skipf(format string, args ...interface{})
+	Skipped() bool
+
+	// A private method to prevent users implementing the
+	// interface and so future additions to it will not
+	// violate Go 1 compatibility.
+	private()
+}
+
+var _ TB = (*T)(nil)
+var _ TB = (*B)(nil)
+
 // T is a type passed to Test functions to manage test state and support formatted test logs.
 // Logs are accumulated during execution and dumped to standard error when done.
 type T struct {
@@ -204,6 +229,8 @@ type T struct {
 	startParallel chan bool // Parallel tests will wait on this.
 }
 
+func (c *common) private() {}
+
 // Fail marks the function as having failed but continues execution.
 func (c *common) Fail() {
 	c.mu.Lock()