Move error message tests from helper test to separate test.

testequal/assertions_test.go

@@ -82,14 +82,27 @@ func TestNotEqual(t *testing.T) {
 	}
 }
 
-type mockT struct{}
+type mockT struct {
+	errMsg string
+}
 
-func (m *mockT) Errorf(format string, args ...interface{}) {}
+func (m *mockT) Errorf(format string, args ...interface{}) {
+	m.errMsg = fmt.Sprintf(format, args...)
+}
 
 func (m *mockT) FailNow() {}
 
 func (m *mockT) Helper() {}
 
+func TestErrorMessage(t *testing.T) {
+	mockT := &mockT{}
+	RequireNotEqual(mockT, 1, 1, "1 != 1")
+	require.Contains(t, mockT.errMsg, "1 != 1")
+
+	RequireEqual(mockT, 1, 2, "%d must be equal to %d", 1, 2)
+	require.Contains(t, mockT.errMsg, "1 must be equal to 2")
+}
+
 func BenchmarkRequireEqualInt64(b *testing.B) {
 	t := &mockT{}
 	b.ResetTimer()

testequal/helper_test.go

@@ -13,7 +13,7 @@ func TestHelper(t *testing.T) {
 	if os.Getenv("FAIL_ASSERTIONS") == "1" {
 		AssertEqual(t, 1, 2, "%d must be equal to %d", 1, 2)
 		AssertNotEqual(t, 1, 1, "1 != 1")
-		RequireEqual(t, 1, 2, errMsgLog{Exp: 1, Act: 2})
+		RequireEqual(t, 1, 2)
 		return
 	}
 
@@ -25,16 +25,9 @@ func TestHelper(t *testing.T) {
 	err := cmd.Run()
 	if e, ok := err.(*exec.ExitError); ok && !e.Success() {
 		require.Contains(t, buf.String(), "helper_test.go:14")
-		require.Contains(t, buf.String(), "1 must be equal to 2")
 		require.Contains(t, buf.String(), "helper_test.go:15")
-		require.Contains(t, buf.String(), "1 != 1")
 		require.Contains(t, buf.String(), "helper_test.go:16")
 		return
 	}
 	t.Fatalf("process ran with err %v, want exit status 1", err)
 }
-
-type errMsgLog struct {
-	Exp int
-	Act int
-}

testequal/t.go

@@ -2,7 +2,8 @@
 
 package testequal
 
-// T is an interface wrapper around *testing.T.
+// T is an interface wrapper for *testing.T
+// that contains only a small subset of methods.
 type T interface {
 	Errorf(format string, args ...interface{})
 	Helper()