Add createCallback to AsyncTestCase

Author: trowski

src/AsyncTestCase.php

@@ -3,6 +3,7 @@
 namespace Amp\PHPUnit;
 
 use Amp\Loop;
+use PHPUnit\Framework\MockObject\MockObject;
 use PHPUnit\Framework\TestCase as PHPUnitTestCase;
 use function Amp\call;
 
@@ -78,4 +79,23 @@ final protected function setTimeout(int $timeout)
 
  Loop::unreference($this->timeoutId);
  }
+
+ /**
+ * @param int $invocationCount Number of times the callback must be invoked or the test will fail.
+ * @param callable|null $returnCallback Callable providing a return value for the callback.
+ *
+ * @return callable|MockObject Mock object having only an __invoke method.
+ */
+ final protected function createCallback(int $invocationCount, callable $returnCallback = null): callable
+ {
+ $mock = $this->createMock(CallbackStub::class);
+ $invocationMocker = $mock->expects($this->exactly($invocationCount))
+ ->method('__invoke');
+
+ if ($returnCallback) {
+ $invocationMocker->willReturnCallback($returnCallback);
+ }
+
+ return $mock;
+ }
 }

test/AsyncTestCaseTest.php

@@ -89,4 +89,13 @@ public function testSetMinimumRunTime()
  $this->expectExceptionMessageRegExp("/Expected test to take at least 100ms but instead took (\d+)ms/");
  yield call($func);
  }
+
+ public function testCreateCallback()
+ {
+ $mock = $this->createCallback(1, function (int $value): int {
+ return $value + 1;
+ });
+
+ $this->assertSame(2, $mock(1));
+ }
 }