1 files changed, 69 insertions, 0 deletions
diff --git a/go/zopfli/zopfli_test.go b/go/zopfli/zopfli_test.go
new file mode 100644
index 0000000..4d61703
--- /dev/null
+++ b/go/zopfli/zopfli_test.go
@@ -0,0 +1,69 @@
+// Copyright 2019 Google LLC
+//
+// 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
+//
+//     https://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 zopfli
+
+import (
+	"bytes"
+	"compress/gzip"
+	"io/ioutil"
+	"math/rand"
+	"strings"
+	"testing"
+)
+
+func getRandomBytes(length uint64) []byte {
+	rng := rand.New(rand.NewSource(1)) // Make test repeatable.
+	data := make([]byte, length)
+	for i := uint64(0); i < length; i++ {
+		data[i] = (byte)(rng.Int())
+	}
+	return data
+}
+
+// TestGzip verifies that Gzip compresses data correctly.
+func TestGzip(t *testing.T) {
+	compressibleString := "compressthis" + strings.Repeat("_foobar", 1000) + "$"
+
+	for _, test := range []struct {
+		name    string
+		data    []byte
+		maxSize int
+	}{
+		{"compressible string", []byte(compressibleString), 500},
+		{"random binary data", getRandomBytes(3000), 3100},
+		{"empty string", []byte(""), 20},
+	} {
+		compressed := Gzip(test.data)
+		gzipReader, err := gzip.NewReader(bytes.NewReader(compressed))
+		if err != nil {
+			t.Errorf("%s: gzip.NewReader: got error %v, expected no error",
+				test.name, err)
+			continue
+		}
+		decompressed, err := ioutil.ReadAll(gzipReader)
+		if err != nil {
+			t.Errorf("%s: reading gzip stream: got error %v, expected no error",
+				test.name, err)
+			continue
+		}
+		if bytes.Compare(test.data, decompressed) != 0 {
+			t.Errorf("%s: mismatch between input and decompressed data", test.name)
+			continue
+		}
+		if test.maxSize > 0 && len(compressed) > test.maxSize {
+			t.Errorf("%s: compressed data is %d bytes, expected %d or less",
+				test.name, len(compressed), test.maxSize)
+		}
+	}
+}