fix: asynchronous route handling (#1137)

playwright/src/main/java/com/microsoft/playwright/impl/BrowserContextImpl.java

@@ -539,10 +539,10 @@ class BrowserContextImpl extends ChannelOwner implements BrowserContext {
 
   void handleRoute(RouteImpl route) {
     Router.HandleResult handled = routes.handle(route);
-    if (handled == Router.HandleResult.FoundMatchingHandler) {
+    if (handled != Router.HandleResult.NoMatchingHandler) {
       maybeDisableNetworkInterception();
     }
-    if (!route.isHandled()){
+    if (handled == Router.HandleResult.NoMatchingHandler || handled == Router.HandleResult.Fallback) {
       route.resume();
     }
   }

playwright/src/main/java/com/microsoft/playwright/impl/PageImpl.java

@@ -188,10 +188,10 @@ public class PageImpl extends ChannelOwner implements Page {
     } else if ("route".equals(event)) {
       RouteImpl route = connection.getExistingObject(params.getAsJsonObject("route").get("guid").getAsString());
       Router.HandleResult handled = routes.handle(route);
-      if (handled == Router.HandleResult.FoundMatchingHandler) {
+      if (handled != Router.HandleResult.NoMatchingHandler) {
         maybeDisableNetworkInterception();
       }
-      if (!route.isHandled()) {
+      if (handled == Router.HandleResult.NoMatchingHandler || handled == Router.HandleResult.Fallback) {
         browserContext.handleRoute(route);
       }
     } else if ("video".equals(event)) {

playwright/src/main/java/com/microsoft/playwright/impl/RouteImpl.java

@@ -34,6 +34,9 @@ public class RouteImpl extends ChannelOwner implements Route {
   private final RequestImpl request;
   private boolean handled;
 
+  boolean fallbackCalled;
+  boolean shouldResumeIfFallbackIsCalled;
+
   public RouteImpl(ChannelOwner parent, String type, String guid, JsonObject initializer) {
     super(parent, type, guid, initializer);
     request = connection.getExistingObject(initializer.getAsJsonObject("request").get("guid").getAsString());
@@ -62,10 +65,14 @@ public class RouteImpl extends ChannelOwner implements Route {
 
   @Override
   public void fallback(FallbackOptions options) {
+    fallbackCalled = true;
     if (handled) {
       throw new PlaywrightException("Route is already handled!");
     }
     applyOverrides(options);
+    if (shouldResumeIfFallbackIsCalled) {
+      resume();
+    }
   }
 
   private void applyOverrides(FallbackOptions options) {

playwright/src/main/java/com/microsoft/playwright/impl/Router.java

@@ -65,7 +65,7 @@ class Router {
     return routes.size();
   }
 
-  enum HandleResult { NoMatchingHandler, FoundMatchingHandler}
+  enum HandleResult { NoMatchingHandler, Handled, Fallback, PendingHandler }
   HandleResult handle(RouteImpl route) {
     HandleResult result = HandleResult.NoMatchingHandler;
     for (Iterator<RouteInfo> it = routes.iterator(); it.hasNext();) {
@@ -76,11 +76,19 @@ class Router {
       if (info.decrementRemainingCallCount()) {
         it.remove();
       }
-      result = HandleResult.FoundMatchingHandler;
+      route.fallbackCalled = false;
       info.handle(route);
       if (route.isHandled()) {
-        break;
+        return HandleResult.Handled;
       }
+      // Not immediately handled and fallback() was not called => the route
+      // must be handled asynchronously.
+      if (!route.fallbackCalled) {
+        route.shouldResumeIfFallbackIsCalled = true;
+        return HandleResult.PendingHandler;
+      }
+      // Fallback was called, continue to the remaining handlers.
+      result = HandleResult.Fallback;
     }
     return result;
   }

playwright/src/test/java/com/microsoft/playwright/TestPageRoute.java

@@ -469,7 +469,7 @@ public class TestPageRoute extends TestBase {
   }
 
   @Test
-  void shouldThrowIfResumeIsCalledAfterRouteHandlerFinished() {
+  void shouldNotThrowIfResumeIsCalledAfterRouteHandlerFinished() {
     page.setContent("<iframe></iframe>");
     Route[] route = {null};
     page.route("**/*", r -> route[0] = r);
@@ -477,8 +477,7 @@ public class TestPageRoute extends TestBase {
     page.waitForRequest("**", () -> page.evalOnSelector("iframe", "(frame, url) => frame.src = url", server.EMPTY_PAGE));
     // Delete frame to cause request to be canceled.
     page.evalOnSelector("iframe", "frame => frame.remove()");
-    PlaywrightException e = assertThrows(PlaywrightException.class, () -> route[0].resume());
-    assertTrue(e.getMessage().contains("Route is already handled!"), e.getMessage());
+    route[0].resume();
   }
 
   @Test
@@ -731,4 +730,77 @@ public class TestPageRoute extends TestBase {
     page.navigate(server.EMPTY_PAGE);
     assertEquals(asList(3, 2, 1), intercepted);
   }
+
+  @Test
+  void shouldAllowToCallRouteAsynchronously() {
+    page.navigate(server.EMPTY_PAGE);
+    Route[] route = new Route[] { null };
+    page.route("**/cars", r -> {
+      route[0] = r;
+    });
+    page.evaluate("async () => {\n" +
+      "      window.didReceiveResponse = false;\n" +
+      "      window.pendingFetch = fetch('/cars', {\n" +
+      "        method: 'POST',\n" +
+      "        headers: { 'Content-Type': 'application/json' },\n" +
+      "        mode: 'cors',\n" +
+      "        body: JSON.stringify({ 'number': 1 })\n" +
+      "      }).then(r => { window.didReceiveResponse = true; return r; });\n" +
+      "    }");
+    while (route[0] == null) {
+      page.waitForTimeout(10);
+    }
+    assertNotNull(route[0]);
+    page.waitForTimeout(1000); // Allow some time for didReceiveResponse to be updated.
+    assertEquals(false, page.evaluate("window.didReceiveResponse"));
+    route[0].fulfill(new Route.FulfillOptions()
+      .setContentType("text/plain")
+      .setStatus(200)
+      .setBody("Hi!"));
+    Object response = page.evaluate("async () => (await pendingFetch).text()\n");
+    assertEquals("Hi!", response);
+  }
+
+  @Test
+  void shouldResumeIfFallbackIsCalledAsynchronously() {
+    page.navigate(server.EMPTY_PAGE);
+    Route[] route = new Route[] { null };
+    page.route("**/simple.json", r -> {
+      route[0] = r;
+    });
+    page.evaluate("async () => {\n" +
+      "      window.didReceiveResponse = false;\n" +
+      "      window.pendingFetch = fetch('" + server.PREFIX + "/simple.json', {\n" +
+      "        method: 'POST',\n" +
+      "        headers: { 'Content-Type': 'application/json' },\n" +
+      "        mode: 'cors',\n" +
+      "        body: JSON.stringify({ 'number': 1 })\n" +
+      "      }).then(r => { window.didReceiveResponse = true; return r; });\n" +
+      "    }");
+    while (route[0] == null) {
+      page.waitForTimeout(10);
+    }
+    assertNotNull(route[0]);
+    page.waitForTimeout(1000); // Allow some time for didReceiveResponse to be updated.
+    assertEquals(false, page.evaluate("window.didReceiveResponse"));
+    route[0].fallback();
+    Object response = page.evaluate("async () => (await pendingFetch).text()\n");
+    assertEquals("{\"foo\": \"bar\"}\n", response);
+  }
+
+  @Test
+  void shouldContinueIfAllHandlersCalledFallback() {
+    List<Integer> intercepted = new ArrayList<>();
+    Predicate<String> predicate = r -> true;
+    page.route(predicate, route -> {
+      intercepted.add(1);
+      route.fallback();
+    });
+    context.route(predicate, route -> {
+      intercepted.add(2);
+      route.fallback();
+    });
+    page.navigate(server.EMPTY_PAGE);
+    assertEquals(asList(1, 2), intercepted);
+  }
 }