1 files changed, 69 insertions, 0 deletions
diff --git a/src/pkg/image/png/writer_test.go b/src/pkg/image/png/writer_test.go
new file mode 100644
index 000000000..b832f1c26
--- /dev/null
+++ b/src/pkg/image/png/writer_test.go
@@ -0,0 +1,69 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package png
+
+import (
+	"fmt";
+	"image";
+	"io";
+	"os";
+	"testing";
+)
+
+func diff(m0, m1 image.Image) os.Error {
+	if m0.Width() != m1.Width() || m0.Height() != m1.Height() {
+		return os.NewError(fmt.Sprintf("dimensions differ: %dx%d vs %dx%d", m0.Width(), m0.Height(), m1.Width(), m1.Height()));
+	}
+	for y := 0; y < m0.Height(); y++ {
+		for x := 0; x < m0.Width(); x++ {
+			r0, g0, b0, a0 := m0.At(x, y).RGBA();
+			r1, g1, b1, a1 := m1.At(x, y).RGBA();
+			if r0 != r1 || g0 != g1 || b0 != b1 || a0 != a1 {
+				return os.NewError(fmt.Sprintf("colors differ at (%d, %d): %v vs %v", x, y, m0.At(x, y), m1.At(x, y)));
+			}
+		}
+	}
+	return nil;
+}
+
+func TestWriter(t *testing.T) {
+	// The filenames variable is declared in reader_test.go.
+	for _, fn := range filenames {
+		qfn := "testdata/pngsuite/" + fn + ".png";
+		// Read the image.
+		m0, err := readPng(qfn);
+		if err != nil {
+			t.Error(fn, err);
+			continue;
+		}
+		// Read the image again, and push it through a pipe that encodes at the write end, and decodes at the read end.
+		pr, pw := io.Pipe();
+		defer pr.Close();
+		go func() {
+			defer pw.Close();
+			m1, err := readPng(qfn);
+			if err != nil {
+				t.Error(fn, err);
+				return;
+			}
+			err = Encode(pw, m1);
+			if err != nil {
+				t.Error(fn, err);
+				return;
+			}
+		}();
+		m2, err := Decode(pr);
+		if err != nil {
+			t.Error(fn, err);
+			continue;
+		}
+		// Compare the two.
+		err = diff(m0, m2);
+		if err != nil {
+			t.Error(fn, err);
+			continue;
+		}
+	}
+}