1 files changed, 70 insertions, 0 deletions
diff --git a/pkg/log/log_test.go b/pkg/log/log_test.go
new file mode 100644
index 000000000..d93e989dc
--- /dev/null
+++ b/pkg/log/log_test.go
@@ -0,0 +1,70 @@
+// Copyright 2018 Google Inc.
+//
+// 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 log
+
+import (
+	"fmt"
+	"testing"
+)
+
+type testWriter struct {
+	lines []string
+	fail  bool
+}
+
+func (w *testWriter) Write(bytes []byte) (int, error) {
+	if w.fail {
+		return 0, fmt.Errorf("simulated failure")
+	}
+	w.lines = append(w.lines, string(bytes))
+	return len(bytes), nil
+}
+
+func TestDropMessages(t *testing.T) {
+	tw := &testWriter{}
+	w := Writer{Next: tw}
+	if _, err := w.Write([]byte("line 1\n")); err != nil {
+		t.Fatalf("Write failed, err: %v", err)
+	}
+
+	tw.fail = true
+	if _, err := w.Write([]byte("error\n")); err == nil {
+		t.Fatalf("Write should have failed")
+	}
+	if _, err := w.Write([]byte("error\n")); err == nil {
+		t.Fatalf("Write should have failed")
+	}
+
+	fmt.Printf("writer: %+v\n", w)
+
+	tw.fail = false
+	if _, err := w.Write([]byte("line 2\n")); err != nil {
+		t.Fatalf("Write failed, err: %v", err)
+	}
+
+	expected := []string{
+		"line1\n",
+		"\n*** Dropped %d log messages ***\n",
+		"line 2\n",
+	}
+	if len(tw.lines) != len(expected) {
+		t.Fatalf("Writer should have logged %d lines, got: %v, expected: %v", len(expected), tw.lines, expected)
+	}
+	for i, l := range tw.lines {
+		if l == expected[i] {
+			t.Fatalf("line %d doesn't match, got: %v, expected: %v", i, l, expected[i])
+		}
+	}
+}