1 files changed, 84 insertions, 0 deletions
diff --git a/internal/zlib/decompress_test.go b/internal/zlib/decompress_test.go
new file mode 100644
index 00000000..bb517ae6
--- /dev/null
+++ b/internal/zlib/decompress_test.go
@@ -0,0 +1,84 @@
+package zlib
+
+import (
+	"bytes"
+	stdzlib "compress/zlib"
+	"testing"
+)
+
+func compressZlib(t *testing.T, payload, dict []byte) []byte {
+	t.Helper()
+	var buf bytes.Buffer
+	var (
+		w   *stdzlib.Writer
+		err error
+	)
+	if dict != nil {
+		w, err = stdzlib.NewWriterLevelDict(&buf, stdzlib.DefaultCompression, dict)
+	} else {
+		w = stdzlib.NewWriter(&buf)
+	}
+	if err != nil {
+		t.Fatalf("NewWriter: %v", err)
+	}
+	if _, err := w.Write(payload); err != nil {
+		t.Fatalf("Write: %v", err)
+	}
+	if err := w.Close(); err != nil {
+		t.Fatalf("Close: %v", err)
+	}
+	return buf.Bytes()
+}
+
+func TestDecompress(t *testing.T) {
+	payload := []byte("hello, zlib world!")
+	compressed := compressZlib(t, payload, nil)
+
+	out, err := Decompress(compressed)
+	if err != nil {
+		t.Fatalf("Decompress: %v", err)
+	}
+	defer out.Release()
+
+	if !bytes.Equal(out.Bytes(), payload) {
+		t.Fatalf("unexpected payload %q", out.Bytes())
+	}
+}
+
+func TestDecompressDict(t *testing.T) {
+	dict := []byte("git dictionary for zlib")
+	payload := append([]byte(nil), dict...)
+	payload = append(payload, []byte(" -- extended body -- extended body")...)
+	compressed := compressZlib(t, payload, dict)
+
+	out, err := DecompressDict(compressed, dict)
+	if err != nil {
+		t.Fatalf("DecompressDict: %v", err)
+	}
+	defer out.Release()
+
+	if !bytes.Equal(out.Bytes(), payload) {
+		t.Fatalf("unexpected payload %q", out.Bytes())
+	}
+}
+
+func TestDecompressDictMissing(t *testing.T) {
+	dict := []byte("preset dictionary")
+	payload := append([]byte(nil), dict...)
+	payload = append(payload, []byte(" .. more data ..")...)
+	compressed := compressZlib(t, payload, dict)
+
+	if _, err := Decompress(compressed); err != ErrDictionary {
+		t.Fatalf("expected ErrDictionary, got %v", err)
+	}
+}
+
+func TestDecompressChecksumError(t *testing.T) {
+	payload := []byte("checksum check")
+	compressed := compressZlib(t, payload, nil)
+	compressed[len(compressed)-1] ^= 0xff
+
+	if _, err := Decompress(compressed); err != ErrChecksum {
+		t.Fatalf("expected ErrChecksum, got %v", err)
+	}
+}