Improve inflate reader test, add comment to zip test

Author: subtle-byte

src/archive/zip/zip_test.go

@@ -35,7 +35,7 @@ func TestOver65kFiles(t *testing.T) {
 	for i := 0; i < nFiles; i++ {
 		_, err := w.CreateHeader(&FileHeader{
 			Name:   fmt.Sprintf("%d.dat", i),
-			Method: Deflate,
+			Method: Deflate, // test Issue 59775
 		})
 		if err != nil {
 			t.Fatalf("creating file %d: %v", i, err)

src/compress/flate/inflate_test.go

@@ -97,35 +97,41 @@ func TestResetDict(t *testing.T) {
 	}
 }
 
-func TestReaderResetReusesReaderBuffer(t *testing.T) {
-	encodedBuf := &bytes.Buffer{}
-	w, _ := NewWriter(encodedBuf, 1)
-	w.Write([]byte("abc"))
-	w.Close()
-
-	encodedNotByteReader := struct{ io.Reader }{encodedBuf}
-
-	f := NewReader(encodedNotByteReader)
-	bufReader1 := f.(*decompressor).r.(*bufio.Reader)
-	f.(Resetter).Reset(encodedNotByteReader, nil)
-	bufReader2 := f.(*decompressor).r.(*bufio.Reader)
-	if bufReader1 != bufReader2 {
-		t.Fatalf("bufio.Reader was not reused")
-	}
-	f.(Resetter).Reset(encodedBuf, nil)
-	bufReader3 := f.(*decompressor).r
-	if bufReader3 != encodedBuf {
-		t.Fatalf("bufio.Reader was reused, but should be used the provided io.ByteReader directly instead")
-	}
-	f.(Resetter).Reset(encodedNotByteReader, nil)
-	_, ok := f.(*decompressor).r.(*bufio.Reader)
-	if !ok {
-		t.Fatalf("new bufio.Reader should be created")
-	}
-	f.Close()
-	f = NewReader(encodedBuf)
-	bufReader4 := f.(*decompressor).r
-	if bufReader4 != encodedBuf {
-		t.Fatalf("bufio.Reader implementing io.ByteReader was not used directly")
-	}
+func TestReaderReusesReaderBuffer(t *testing.T) {
+	encodedReader := bytes.NewReader([]byte{})
+	encodedNotByteReader := struct{ io.Reader }{encodedReader}
+
+	t.Run("BufferIsReused", func(t *testing.T) {
+		f := NewReader(encodedNotByteReader).(*decompressor)
+		bufioR, ok := f.r.(*bufio.Reader)
+		if !ok {
+			t.Fatalf("bufio.Reader should be created")
+		}
+		f.Reset(encodedNotByteReader, nil)
+		if bufioR != f.r {
+			t.Fatalf("bufio.Reader was not reused")
+		}
+	})
+	t.Run("BufferIsNotReusedWhenGotByteReader", func(t *testing.T) {
+		f := NewReader(encodedNotByteReader).(*decompressor)
+		if _, ok := f.r.(*bufio.Reader); !ok {
+			t.Fatalf("bufio.Reader should be created")
+		}
+		f.Reset(encodedReader, nil)
+		if f.r != encodedReader {
+			t.Fatalf("provided io.ByteReader should be used directly")
+		}
+	})
+	t.Run("BufferIsCreatedAfterByteReader", func(t *testing.T) {
+		for i, r := range []io.Reader{encodedReader, bufio.NewReader(encodedReader)} {
+			f := NewReader(r).(*decompressor)
+			if f.r != r {
+				t.Fatalf("provided io.ByteReader should be used directly, i=%d", i)
+			}
+			f.Reset(encodedNotByteReader, nil)
+			if _, ok := f.r.(*bufio.Reader); !ok {
+				t.Fatalf("bufio.Reader should be created, i=%d", i)
+			}
+		}
+	})
 }