[integration_test] Test drivers should end with  `_test.dart` (#3063)

This makes globbing by tooling easier.

Also fix the documentation for running them natively with the Android and iOS tool.
diff --git a/.cirrus.yml b/.cirrus.yml
index 25396ea..872cfc2 100644
--- a/.cirrus.yml
+++ b/.cirrus.yml
@@ -59,7 +59,7 @@
         - ./chromedriver/chromedriver --port=4444 &
       test_script:
         - cd $INTEGRATION_TEST_PATH/example/
-        - flutter drive -v --driver=test_driver/integration_test_driver.dart --target=integration_test/example_test.dart -d web-server --release --browser-name=chrome
+        - flutter drive -v --driver=test_driver/integration_test.dart --target=integration_test/example_test.dart -d web-server --release --browser-name=chrome
     - name: build-apks+java-test+firebase-test-lab
       env:
         matrix:
diff --git a/packages/integration_test/README.md b/packages/integration_test/README.md
index a6b1726..be08a72 100644
--- a/packages/integration_test/README.md
+++ b/packages/integration_test/README.md
@@ -30,8 +30,8 @@
 ### Driver Entrypoint
 
 An accompanying driver script will be needed that can be shared across all
-integration tests. Create a `integration_test_driver.dart` in the `test_driver/`
-directory with the following contents:
+integration tests. Create a file named `integration_test.dart` in the
+`test_driver/` directory with the following contents:
 
 ```dart
 import 'package:integration_test/integration_test_driver.dart';
@@ -57,7 +57,7 @@
 test/
   # Other unit tests go here.
 test_driver/
-  integration_test_driver.dart
+  integration_test.dart
 ```
 
 [Example](https://github.com/flutter/plugins/tree/master/packages/integration_test/example)
@@ -67,11 +67,11 @@
 These tests can be launched with the `flutter drive` command.
 
 To run the `integration_test/foo_test.dart` test with the
-`test_driver/integration_test_driver.dart` driver, use the following command:
+`test_driver/integration_test.dart` driver, use the following command:
 
 ```sh
 flutter drive \
-  --driver=test_driver/integration_test_driver.dart \
+  --driver=test_driver/integration_test.dart \
   --target=integration_test/foo_test.dart
 ```
 
@@ -85,7 +85,7 @@
 
 ```sh
 flutter drive \
-  --driver=test_driver/integration_test_driver.dart \
+  --driver=test_driver/integration_test.dart \
   --target=integration_test/foo_test.dart \
   -d web-server
 ```
@@ -134,10 +134,11 @@
 }
 ```
 
-To run a test on a local Android device (emulated or physical):
+To run `integration_test/foo_test.dart` on a local Android device (emulated or
+physical):
 
 ```sh
-./gradlew app:connectedAndroidTest -Ptarget=`pwd`/../test_driver/<package_name>_integration_test.dart
+./gradlew app:connectedAndroidTest -Ptarget=`pwd`/../integration_test/foo_test.dart
 ```
 
 ## Firebase Test Lab
@@ -189,10 +190,12 @@
 end
 ```
 
-To run a test on your iOS device (simulator or real), rebuild your iOS targets with Flutter tool.
+To run `integration_test/foo_test.dart` on your iOS device, rebuild your iOS
+targets with Flutter tool.
 
 ```sh
-flutter build ios -t test_driver/<package_name>_integration_test.dart (--simulator)
+# Pass --simulator if building for the simulator.
+flutter build ios integration_test/foo_test.dart
 ```
 
 Open Xcode project (by default, it's `ios/Runner.xcodeproj`). Create a test target
diff --git a/packages/integration_test/example/README.md b/packages/integration_test/example/README.md
index 7e6317f..b5cc5d7 100644
--- a/packages/integration_test/example/README.md
+++ b/packages/integration_test/example/README.md
@@ -8,7 +8,7 @@
 
 ```sh
 flutter drive \
-  --driver=test_driver/integration_test_driver.dart \
+  --driver=test_driver/integration_test.dart \
   --target=integration_test/example_test.dart
 ```
 
@@ -16,7 +16,7 @@
 
 ```sh
 flutter drive \
-  --driver=test_driver/integration_test_driver.dart \
+  --driver=test_driver/integration_test.dart \
   --target=integration_test/example_test.dart \
   -d web-server
 ```
diff --git a/packages/integration_test/example/test_driver/integration_test_extended_driver.dart b/packages/integration_test/example/test_driver/extended_integration_test.dart
similarity index 100%
rename from packages/integration_test/example/test_driver/integration_test_extended_driver.dart
rename to packages/integration_test/example/test_driver/extended_integration_test.dart
diff --git a/packages/integration_test/example/integration_test/failure_test.dart b/packages/integration_test/example/test_driver/failure.dart
similarity index 77%
rename from packages/integration_test/example/integration_test/failure_test.dart
rename to packages/integration_test/example/test_driver/failure.dart
index ffb569f..02fc55e 100644
--- a/packages/integration_test/example/integration_test/failure_test.dart
+++ b/packages/integration_test/example/test_driver/failure.dart
@@ -8,6 +8,12 @@
 
 import 'package:integration_test_example/main.dart' as app;
 
+/// This file is placed in `test_driver/` instead of `integration_test/`, so
+/// that the CI tooling of flutter/plugins only uses this together with
+/// `failure_test.dart` as the driver. It is only used for testing of
+/// `package:integration_test` – do not follow the conventions here if you are a
+/// user of `package:integration_test`.
+
 // Tests the failure behavior of the IntegrationTestWidgetsFlutterBinding
 //
 // This test fails intentionally! It should be run using a test runner that
diff --git a/packages/integration_test/example/test_driver/integration_test_failure_driver.dart b/packages/integration_test/example/test_driver/failure_test.dart
similarity index 76%
rename from packages/integration_test/example/test_driver/integration_test_failure_driver.dart
rename to packages/integration_test/example/test_driver/failure_test.dart
index 0b60e47..fce6adc 100644
--- a/packages/integration_test/example/test_driver/integration_test_failure_driver.dart
+++ b/packages/integration_test/example/test_driver/failure_test.dart
@@ -2,6 +2,9 @@
 import 'package:integration_test/common.dart' as common;
 import 'package:test/test.dart';
 
+/// This file is only used for testing of `package:integration_test` – do not
+/// follow the conventions here if you are a user of `package:integration_test`.
+
 Future<void> main() async {
   test('fails gracefully', () async {
     final FlutterDriver driver = await FlutterDriver.connect();
diff --git a/packages/integration_test/example/test_driver/integration_test_driver.dart b/packages/integration_test/example/test_driver/integration_test.dart
similarity index 100%
rename from packages/integration_test/example/test_driver/integration_test_driver.dart
rename to packages/integration_test/example/test_driver/integration_test.dart