Add assertTrueAboutPromise() and assertFalseAboutPromise()

README.md

@@ -18,6 +18,8 @@ assertions for testing ReactPHP promises.
     - [assertPromiseFulfillsWithInstanceOf()](#assertpromisefulfillswithinstanceof)
     - [assertPromiseRejects()](#assertpromiserejects())
     - [assertPromiseRejectsWith()](#assertpromiserejectswith)
+    - [assertTrueAboutPromise](#asserttrueaboutpromise)
+    - [assertFalseAboutPromise](#assertfalseaboutpromise)
 
 - [Helpers](#helpers)
     - [waitForPromiseToFulfill()](#waitforpromisetofulfill)
@@ -246,6 +248,81 @@ Failed asserting that promise rejects with a specified reason.
 Failed asserting that LogicException Object (...) is an instance of class "InvalidArgumentException".
 ```
 
+### assertTrueAboutPromise()
+`assertTrueAboutPromise(PromiseInterface $promise, callable $predicate, int $timeout = null): void`
+
+The test fails if the value encapsulated in the Promise does not conform to an arbitrary predicate.
+
+You can specify `$timeout` in seconds to wait for promise to be resolved.
+If the promise was not fulfilled in specified timeout, it rejects with `React\Promise\Timer\TimeoutException`. 
+When not specified, timeout is set to 2 seconds.
+
+```php
+final class AssertTrueAboutPromiseTest extends TestCase
+{
+    /** @test */
+    public function promise_encapsulates_integer(): void
+    {
+        $deferred = new Deferred();
+        $deferred->resolve(23);
+
+        $this->assertTrueAboutPromise($deferred->promise(), function ($val) {
+            return is_object($val);
+        });
+    }
+}
+```
+
+```bash
+PHPUnit 8.5.2 by Sebastian Bergmann and contributors.
+
+F                                                                   1 / 1 (100%)
+
+Time: 136 ms, Memory: 4.00MB
+
+There was 1 failure:
+
+1) seregazhuk\React\PromiseTesting\tests\AssertTrueAboutPromiseTest::promise_encapsulates_integer
+Failed asserting that false is true.
+```
+
+### assertFalseAboutPromise()
+`assertFalseAboutPromise(PromiseInterface $promise, callable $predicate, int $timeout = null): void`
+
+The test fails if the value encapsulated in the Promise conforms to an arbitrary predicate.
+
+You can specify `$timeout` in seconds to wait for promise to be resolved.
+If the promise was not fulfilled in specified timeout, it rejects with `React\Promise\Timer\TimeoutException`. 
+When not specified, timeout is set to 2 seconds.
+
+```php
+final class AssertFalseAboutPromiseTest extends TestCase
+{
+    /** @test */
+    public function promise_encapsulates_object(): void
+    {
+        $deferred = new Deferred();
+        $deferred->resolve(23);
+
+        $this->assertFalseAboutPromise($deferred->promise(), function ($val) {
+            return is_int($val);
+        });
+    }
+}
+```
+
+```bash
+PHPUnit 8.5.2 by Sebastian Bergmann and contributors.
+
+F                                                                   1 / 1 (100%)
+
+Time: 136 ms, Memory: 4.00MB
+
+There was 1 failure:
+
+1) seregazhuk\React\PromiseTesting\tests\AssertFalseAboutPromiseTest::promise_encapsulates_object
+Failed asserting that true is false.
+```
 
 ## Helpers
 

src/TestCase.php

@@ -64,6 +64,34 @@ public function assertPromiseFulfillsWith(PromiseInterface $promise, $value, int
         $this->assertEquals($value, $result, $failMessage);
     }
 
+    /**
+     * @param PromiseInterface $promise
+     * @param callable $predicate
+     * @param int|null $timeout
+     * @throws AssertionFailedError
+     */
+    public function assertTrueAboutPromise(
+        PromiseInterface $promise, 
+        callable $predicate, 
+        int $timeout = null
+    ): void {
+        $this->assertAboutPromise($promise, $predicate, $timeout);
+    }
+
+    /**
+     * @param PromiseInterface $promise
+     * @param callable $predicate
+     * @param int|null $timeout
+     * @throws AssertionFailedError
+     */
+    public function assertFalseAboutPromise(
+        PromiseInterface $promise, 
+        callable $predicate, 
+        int $timeout = null
+    ): void {
+        $this->assertAboutPromise($promise, $predicate, $timeout, false);
+    }
+
     /**
      * @throws AssertionFailedError
      */
@@ -145,4 +173,31 @@ public function eventLoop(): LoopInterface
     {
         return $this->loop;
     }
+
+    /**
+     * @param PromiseInterface $promise
+     * @param callable $predicate
+     * @param int|null $timeout
+     * @param bool $assertTrue
+     * @throws AssertionFailedError
+     */
+    private function assertAboutPromise(
+        PromiseInterface $promise,
+        callable $predicate,
+        int $timeout = null,
+        bool $assertTrue = true
+    ): void {
+        $result = $assertTrue ? false : true;
+        $this->addToAssertionCount(1);
+
+        try {
+            $result = $predicate($this->waitForPromise($promise, $timeout));
+        } catch (TimeoutException $exception) {
+            $this->fail('Promise was cancelled due to timeout');
+        } catch (Exception $exception) {
+            $this->fail('Failed asserting that promise was fulfilled. Promise was rejected');
+        }
+
+        $assertTrue ? $this->assertTrue($result) : $this->assertFalse($result);
+    }
 }

tests/AboutPromiseTest.php

@@ -0,0 +1,68 @@
+<?php
+
+namespace seregazhuk\React\PromiseTesting\tests;
+
+use Exception;
+use React\Promise\Deferred;
+use seregazhuk\React\PromiseTesting\TestCase;
+
+final class AboutPromiseTest extends TestCase
+{
+	/** @test */
+	public function predicate_function_reveals_what_is_true_about_promise(): void
+	{
+		try {
+			$fst = new Deferred;
+      		$fst->resolve(23);
+
+			$snd = new Deferred;
+			$snd->reject(new Exception('An error'));
+
+			$thd = new Deferred;
+			$thd->reject('Another error');
+
+			$this->assertTrueAboutPromise($fst->promise(), function ($val): bool {
+				return is_int($val) && $val > 20;
+			});
+			$this->assertTrueAboutPromise($fst->promise(), 'is_string');
+
+			$this->assertTrueAboutPromise($snd->promise(), 'is_string');
+
+			$this->assertTrueAboutPromise($thd->promise(), 'is_string');
+		} catch (Exception $exception) {
+			$this->assertRegExp(
+				'/Failed asserting that .+/',
+				$exception->getMessage()
+			);
+		}
+	}
+
+	/** @test */
+	public function predicate_function_reveals_what_is_false_about_promise(): void
+	{
+		try {
+			$fst = new Deferred;
+			$fst->resolve(23);
+
+			$snd = new Deferred;
+			$snd->reject(new Exception('An error'));
+
+			$thd = new Deferred;
+			$thd->reject('Another error');
+
+			$this->assertFalseAboutPromise($fst->promise(), function ($val): bool {
+				return is_int($val) && $val > 20;
+			});
+			$this->assertFalseAboutPromise($fst->promise(), 'is_string');
+
+			$this->assertFalseAboutPromise($snd->promise(), 'is_string');
+
+			$this->assertFalseAboutPromise($thd->promise(), 'is_int');
+		} catch (Exception $exception) {
+			$this->assertRegExp(
+				'/Failed asserting that .+/',
+				$exception->getMessage()
+			);
+		}
+	}
+}