Update api.Client for isolated read-after-write support

vault/client_test.go

@@ -239,6 +239,19 @@ func setupServer(t *testing.T, handler http.Handler) (*ClientFactory, *http.Serv
 	return w, server
 }
 
+func validateResponseHeader(client *api.Client, headerValue string) error {
+	resp, err := sendRequest(client, headerValue)
+	if err != nil {
+		return err
+	}
+	// validate that the server provided a valid header value in its response
+	actual := resp.Header.Get(indexHeaderName)
+	if actual != headerValue {
+		return fmt.Errorf("expected header value %v, actual %v", headerValue, actual)
+	}
+	return nil
+}
+
 func TestClientFactory_Client(t *testing.T) {
 	b64enc := func(s string) string {
 		return base64.StdEncoding.EncodeToString([]byte(s))
@@ -289,16 +302,7 @@ func TestClientFactory_Client(t *testing.T) {
 				wg.Add(1)
 				go func(expected string) {
 					defer wg.Done()
-
-					resp, err := sendRequest(client, expected)
-					if err != nil {
-						t.Fatal(err)
-					}
-					// validate that the server provided a valid header value in its response
-					actual := resp.Header.Get(indexHeaderName)
-					if actual != expected {
-						t.Errorf("expected header value %v, actual %v", expected, actual)
-					}
+					validateResponseHeader(client, expected)
 				}(expected)
 			}
 			wg.Wait()
@@ -309,3 +313,91 @@ func TestClientFactory_Client(t *testing.T) {
 		})
 	}
 }
+
+func TestClientFactory_Clone(t *testing.T) {
+	b64enc := func(s string) string {
+		return base64.StdEncoding.EncodeToString([]byte(s))
+	}
+
+	handler := http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
+		w.Header().Set(indexHeaderName, strings.TrimLeft(req.URL.Path, "/"))
+	})
+
+	tests := []struct {
+		name       string
+		handler    http.Handler
+		wantStates []string
+		states     []struct {
+			h1 string
+			h2 string
+		}
+	}{
+		{
+			name:    "basic",
+			handler: handler,
+			wantStates: []string{
+				b64enc("v1:cid:0:1:"),
+				b64enc("v1:cid:1:0:"),
+			},
+			states: []struct {
+				h1 string
+				h2 string
+			}{
+				{
+					h1: b64enc("v1:cid:0:1:"),
+					h2: b64enc("v1:cid:1:0:"),
+				},
+			},
+		},
+		{
+			name:    "multiple",
+			handler: handler,
+			wantStates: []string{
+				b64enc("v1:cid:0:2:"),
+				b64enc("v1:cid:2:0:"),
+			},
+			states: []struct {
+				h1 string
+				h2 string
+			}{
+				{
+					h1: b64enc("v1:cid:0:1:"),
+					h2: b64enc("v1:cid:1:0:"),
+				},
+				{
+					h1: b64enc("v1:cid:0:2:"),
+					h2: b64enc("v1:cid:2:0:"),
+				},
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+
+			w, server := setupServer(t, tt.handler)
+			defer server.Close()
+
+			c1 := w.Client()
+			c2, err := w.Clone()
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			var wg sync.WaitGroup
+			for _, headers := range tt.states {
+				wg.Add(1)
+				go func(headerVal string) {
+					defer wg.Done()
+					validateResponseHeader(c1, headerVal)
+
+				}(headers.h1)
+				validateResponseHeader(c2, headers.h2)
+			}
+			wg.Wait()
+
+			if !reflect.DeepEqual(tt.wantStates, w.states) {
+				t.Errorf("RawRequestWithContext(): expected states %v, actual %v", tt.wantStates, w.states)
+			}
+		})
+	}
+}