assert: Add Error and ErrorContains

nhooyr · nhooyr · commit f73b26e4c118 · 2019-12-12T15:23:00.000-06:00
diff --git a/sloggers/slogtest/assert/assert.go b/sloggers/slogtest/assert/assert.go
@@ -1,7 +1,12 @@
 // Package assert is a helper package for test assertions.
+//
+// On failure, every assertion will fatal the test.
+//
+// The name parameter is available in each assertion for easier debugging.
 package assert // import "cdr.dev/slog/sloggers/slogtest/assert"
 
 import (
+	"strings"
 	"testing"
 
 	"cdr.dev/slog"
@@ -24,8 +29,6 @@ func Equal(t testing.TB, exp, act interface{}, name string) {
 }
 
 // Success asserts err == nil.
-//
-// If err isn't nil, it will fatal the test with the error.
 func Success(t testing.TB, err error, name string) {
 	slog.Helper()
 	if err != nil {
@@ -37,9 +40,39 @@ func Success(t testing.TB, err error, name string) {
 }
 
 // True asserts act == true.
-//
-// If act isn't true, it will fatal the test.
 func True(t testing.TB, act bool, name string) {
 	slog.Helper()
 	Equal(t, true, act, name)
 }
+
+// Error asserts err != nil.
+func Error(t testing.TB, err error, name string) {
+	slog.Helper()
+	if err == nil {
+		slogtest.Fatal(t, "expected error",
+			slog.F("name", name),
+		)
+	}
+}
+
+// ErrorContains asserts err != nil and err.Error() contains sub.
+//
+// The match will be case insensitive.
+func ErrorContains(t testing.TB, err error, sub, name string) {
+	slog.Helper()
+	Error(t, err, name)
+	errs := err.Error()
+	if !stringContainsFold(errs, sub) {
+		slogtest.Fatal(t, "unexpected error string",
+			slog.F("name", name),
+			slog.F("error_string", errs),
+			slog.F("expected_substring", sub),
+		)
+	}
+}
+
+func stringContainsFold(errs, sub string) bool {
+	errs = strings.ToLower(errs)
+	sub = strings.ToLower(sub)
+	return strings.Contains(errs, sub)
+}
diff --git a/sloggers/slogtest/assert/assert_test.go b/sloggers/slogtest/assert/assert_test.go
@@ -47,6 +47,32 @@ func TestTrue(t *testing.T) {
 	assert.True(tb, false, "meow")
 }
 
+func TestError(t *testing.T) {
+	t.Parallel()
+
+	tb := &fakeTB{}
+	assert.Error(tb, io.EOF, "meow")
+
+	defer func() {
+		recover()
+		simpleassert.Equal(t, 1, tb.fatals, "fatals")
+	}()
+	assert.Error(tb, nil, "meow")
+}
+
+func TestErrorContains(t *testing.T) {
+	t.Parallel()
+
+	tb := &fakeTB{}
+	assert.ErrorContains(tb, io.EOF, "eof", "meow")
+
+	defer func() {
+		recover()
+		simpleassert.Equal(t, 1, tb.fatals, "fatals")
+	}()
+	assert.ErrorContains(tb, io.ErrClosedPipe, "eof", "meow")
+}
+
 type fakeTB struct {
 	testing.TB
 
