perf(matchers): simplify http.NoBody case

Signed-off-by: Maxime Soulé <btik-git@scoubidou.com>

match.go

@@ -466,8 +466,8 @@ func (m matchRouteKey) String() string {
 }
 
 // bodyCopyOnRead copies body content to buf on first Read(), except
-// if body is nil. In this case, EOF is returned for each Read() and
-// buf stays to nil.
+// if body is nil or http.NoBody. In this case, EOF is returned for
+// each Read() and buf stays to nil.
 type bodyCopyOnRead struct {
 	body io.ReadCloser
 	buf  []byte
@@ -480,7 +480,7 @@ func (b *bodyCopyOnRead) rearm() {
 }
 
 func (b *bodyCopyOnRead) copy() {
-	if b.buf == nil && b.body != nil {
+	if b.buf == nil && b.body != nil && b.body != http.NoBody {
 		var body bytes.Buffer
 		io.Copy(&body, b.body) //nolint: errcheck
 		b.body.Close()
@@ -500,3 +500,9 @@ func (b *bodyCopyOnRead) Read(p []byte) (n int, err error) {
 func (b *bodyCopyOnRead) Close() error {
 	return nil
 }
+
+// Len returns the buffer total length, whatever the Read position in body is.
+func (b *bodyCopyOnRead) Len() int {
+	b.copy()
+	return len(b.buf)
+}

match_test.go

@@ -418,28 +418,71 @@ func TestBodyCopyOnRead(t *testing.T) {
 		td.CmpNoError(t, bc.Close())
 	})
 
-	t.Run("nil body", func(t *testing.T) {
-		bc := httpmock.NewBodyCopyOnRead(nil)
-
-		bc.Rearm()
-		td.CmpNil(t, bc.Buf())
-
-		var buf [4]byte
-		n, err := bc.Read(buf[:])
-		td.Cmp(t, err, io.EOF)
-		td.Cmp(t, n, 0)
-		td.CmpNil(t, bc.Buf())
-		td.Cmp(t, bc.Body(), nil)
-
-		bc.Rearm()
-
-		n, err = bc.Read(buf[:])
-		td.Cmp(t, err, io.EOF)
-		td.Cmp(t, n, 0)
-		td.CmpNil(t, bc.Buf())
-		td.Cmp(t, bc.Body(), nil)
+	testCases := []struct {
+		name string
+		body io.ReadCloser
+	}{
+		{
+			name: "nil body",
+		},
+		{
+			name: "no body",
+			body: http.NoBody,
+		},
+	}
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			bc := httpmock.NewBodyCopyOnRead(tc.body)
+
+			bc.Rearm()
+			td.CmpNil(t, bc.Buf())
+
+			var buf [4]byte
+			n, err := bc.Read(buf[:])
+			td.Cmp(t, err, io.EOF)
+			td.Cmp(t, n, 0)
+			td.CmpNil(t, bc.Buf())
+			td.Cmp(t, bc.Body(), tc.body)
+
+			bc.Rearm()
+
+			n, err = bc.Read(buf[:])
+			td.Cmp(t, err, io.EOF)
+			td.Cmp(t, n, 0)
+			td.CmpNil(t, bc.Buf())
+			td.Cmp(t, bc.Body(), tc.body)
+
+			td.CmpNoError(t, bc.Close())
+		})
+	}
 
-		td.CmpNoError(t, bc.Close())
+	t.Run("len", func(t *testing.T) {
+		testCases := []struct {
+			name     string
+			bc       interface{ Len() int }
+			expected int
+		}{
+			{
+				name:     "nil",
+				bc:       httpmock.NewBodyCopyOnRead(nil),
+				expected: 0,
+			},
+			{
+				name:     "no body",
+				bc:       httpmock.NewBodyCopyOnRead(http.NoBody),
+				expected: 0,
+			},
+			{
+				name:     "filled",
+				bc:       httpmock.NewBodyCopyOnRead(ioutil.NopCloser(bytes.NewReader([]byte(`BODY`)))),
+				expected: 4,
+			},
+		}
+		for _, tc := range testCases {
+			t.Run(tc.name, func(t *testing.T) {
+				td.Cmp(t, tc.bc.Len(), tc.expected)
+			})
+		}
 	})
 }