Added Errors.Is

errors.go

@@ -59,6 +59,17 @@ func (errs *Errors) Error() string {
 	return strings.Join(ss, " && ")
 }
 
+func (errs *Errors) Is(target error) bool {
+	errs.m.Lock()
+	defer errs.m.Unlock()
+	for _, v := range errs.p {
+		if errors.Is(v, target) {
+			return true
+		}
+	}
+	return false
+}
+
 // ErrorCause returns the cause of an error
 func ErrorCause(err error) error {
 	for {

errors_test.go

@@ -26,6 +26,31 @@ func TestErrors(t *testing.T) {
 		}
 		return false
 	})
+	err1 := errors.New("1")
+	err2 := errors.New("2")
+	err3 := errors.New("3")
+	errs = NewErrors(err1, err3)
+	for _, v := range []struct {
+		err      error
+		expected bool
+	}{
+		{
+			err:      err1,
+			expected: true,
+		},
+		{
+			err:      err2,
+			expected: false,
+		},
+		{
+			err:      err3,
+			expected: true,
+		},
+	} {
+		if g := errors.Is(errs, v.err); g != v.expected {
+			t.Errorf("expected %v, got %v", v.expected, g)
+		}
+	}
 }
 
 func TestErrorCause(t *testing.T) {