ZLIB deflater.

R=rsc
APPROVED=rsc
DELTA=222  (219 added, 0 deleted, 3 changed)
OCL=35031
CL=35129

1 files changed, 105 insertions, 0 deletions

diff --git a/src/pkg/compress/zlib/writer_test.go b/src/pkg/compress/zlib/writer_test.go
new file mode 100644
index 000000000..ee041d050
--- /dev/null
+++ b/src/pkg/compress/zlib/writer_test.go
@@ -0,0 +1,105 @@
+// 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 zlib
+
+import (
+	"io";
+	"os";
+	"testing";
+)
+
+var filenames = []string {
+	"testdata/e.txt",
+	"testdata/pi.txt",
+}
+
+// Tests that compressing and then decompressing the given file at the given compression level
+// yields equivalent bytes to the original file.
+func testFileLevel(t *testing.T, fn string, level int) {
+	// Read the file, as golden output.
+	golden, err := os.Open(fn, os.O_RDONLY, 0444);
+	if err != nil {
+		t.Errorf("%s (level=%d): %v", fn, level, err);
+		return;
+	}
+	defer golden.Close();
+
+	// Read the file again, and push it through a pipe that compresses at the write end, and decompresses at the read end.
+	raw, err := os.Open(fn, os.O_RDONLY, 0444);
+	if err != nil {
+		t.Errorf("%s (level=%d): %v", fn, level, err);
+		return;
+	}
+	piper, pipew := io.Pipe();
+	defer piper.Close();
+	go func() {
+		defer raw.Close();
+		defer pipew.Close();
+		zlibw, err := NewDeflaterLevel(pipew, level);
+		if err != nil {
+			t.Errorf("%s (level=%d): %v", fn, level, err);
+			return;
+		}
+		defer zlibw.Close();
+		var b [1024]byte;
+		for {
+			n, err0 := raw.Read(&b);
+			if err0 != nil && err0 != os.EOF {
+				t.Errorf("%s (level=%d): %v", fn, level, err0);
+				return;
+			}
+			_, err1 := zlibw.Write(b[0:n]);
+			if err1 == os.EPIPE {
+				// Fail, but do not report the error, as some other (presumably reportable) error broke the pipe.
+				return;
+			}
+			if err1 != nil {
+				t.Errorf("%s (level=%d): %v", fn, level, err1);
+				return;
+			}
+			if err0 == os.EOF {
+				break;
+			}
+		}
+	}();
+	zlibr, err := NewInflater(piper);
+	if err != nil {
+		t.Errorf("%s (level=%d): %v", fn, level, err);
+		return;
+	}
+	defer zlibr.Close();
+
+	// Compare the two.
+	b0, err0 := io.ReadAll(golden);
+	b1, err1 := io.ReadAll(zlibr);
+	if err0 != nil {
+		t.Errorf("%s (level=%d): %v", fn, level, err0);
+		return;
+	}
+	if err1 != nil {
+		t.Errorf("%s (level=%d): %v", fn, level, err1);
+		return;
+	}
+	if len(b0) != len(b1) {
+		t.Errorf("%s (level=%d): length mismatch %d versus %d", fn, level, len(b0), len(b1));
+		return;
+	}
+	for i := 0; i < len(b0); i++ {
+		if b0[i] != b1[i] {
+			t.Errorf("%s (level=%d): mismatch at %d, 0x%02x versus 0x%02x\n", fn, level, i, b0[i], b1[i]);
+			return;
+		}
+	}
+}
+
+func TestWriter(t *testing.T) {
+	for _, fn := range filenames {
+		testFileLevel(t, fn, DefaultCompression);
+		testFileLevel(t, fn, NoCompression);
+		for level := BestSpeed; level <= BestCompression; level++ {
+			testFileLevel(t, fn, level);
+		}
+	}
+}