Feature/async catch backport (#431)

* Add async catch method (#430)

* Only 4.5 and netstandard supported

Author: robertcoltheart

src/Examples/Example.Random/AsyncSpecificationsValueTask.cs

@@ -0,0 +1,40 @@
+using System.Threading.Tasks;
+using Machine.Specifications;
+
+#if !NET45
+namespace Example.Random
+{
+    public class AsyncSpecificationsValueTask
+    {
+        public static int establish_value;
+
+        public static int because_value;
+
+        public static int async_it_value;
+
+        public static int sync_it_value;
+
+        public static int cleanup_value;
+
+        public static ValueTask<int> Test()
+        {
+            return new ValueTask<int>(10);
+        }
+
+        Establish context = async () =>
+            establish_value = await Test();
+
+        Because of = async () =>
+            because_value = await Test();
+
+        It should_invoke_sync = () =>
+            sync_it_value = Test().Result;
+
+        It should_invoke_async = async () =>
+            async_it_value = await Test();
+
+        Cleanup after = async () =>
+            cleanup_value = await Test();
+    }
+}
+#endif

src/Machine.Specifications.Specs/CatchSpecs.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Threading.Tasks;
 
 using FluentAssertions;
 
@@ -125,7 +126,52 @@ public class with_a_non_throwing_Action
         () => ActionSideEffect.Should().Be("hi");
 
       It should_return_null =
-        () => Result.Should().BeNull();
+          () => Result.Should().BeNull();
+        }
     }
-  }
-}
+
+    [Subject(typeof(Catch))]
+    public class when_calling_catch_with_async_methods
+    {
+        static Exception exception;
+
+        [Subject(typeof(Catch))]
+        public class with_a_non_throwing_action
+        {
+            static Task Test() => Task.Run(() => { });
+
+            Because of = async () =>
+                exception = await Catch.ExceptionAsync(Test);
+
+            It should_return_null = () =>
+                exception.Should().BeNull();
+        }
+
+        [Subject(typeof(Catch))]
+        public class with_a_throwing_action
+        {
+            static Task Test() => Task.Run(() => throw new ArgumentNullException());
+
+            Because of = async () =>
+                exception = await Catch.ExceptionAsync(Test);
+
+            It should_return_exception = () =>
+                exception.Should().BeOfType<ArgumentNullException>();
+        }
+
+        [Subject(typeof(Catch))]
+        public class calling_wrong_catch_method
+        {
+            static Task Test() => Task.Run(() => throw new ArgumentNullException());
+
+            Because of = () =>
+                exception = Catch.Exception(() => Catch.Exception(Test));
+
+            It should_return_exception = () =>
+                exception.Should().BeOfType<InvalidOperationException>();
+
+            It should_contain_message = () =>
+                exception.Message.Should().Be("You must use Catch.ExceptionAsync for async methods");
+        }
+    }
+}

src/Machine.Specifications.Specs/Runner/AsyncDelegateRunnerSpecs.cs

@@ -69,4 +69,37 @@ public class when_running_async_specifications_with_exceptions : RunnerSpecs
         It should_have_failures = () =>
             results.Should().Match(x => x.All(y => !y.Passed));
     }
+
+#if NETCOREAPP
+    [Subject("Async Delegate Runner")]
+    public class when_running_async_value_task_specifications : RunnerSpecs
+    {
+        Establish context = () =>
+        {
+            AsyncSpecificationsValueTask.establish_value = 0;
+            AsyncSpecificationsValueTask.because_value = 0;
+            AsyncSpecificationsValueTask.async_it_value = 0;
+            AsyncSpecificationsValueTask.sync_it_value = 0;
+            AsyncSpecificationsValueTask.cleanup_value = 0;
+        };
+
+        Because of = () =>
+            Run<AsyncSpecificationsValueTask>();
+
+        It should_call_establish = () =>
+            AsyncSpecificationsValueTask.establish_value.Should().Be(10);
+
+        It should_call_because = () =>
+            AsyncSpecificationsValueTask.because_value.Should().Be(10);
+
+        It should_call_async_spec = () =>
+            AsyncSpecificationsValueTask.async_it_value.Should().Be(10);
+
+        It should_call_sync_spec = () =>
+            AsyncSpecificationsValueTask.sync_it_value.Should().Be(10);
+
+        It should_call_cleanup = () =>
+            AsyncSpecificationsValueTask.cleanup_value.Should().Be(10);
+    }
+#endif
 }

src/Machine.Specifications.Specs/TaskSpecificationExtensionsSpecs.cs

@@ -50,17 +50,6 @@ public class when_an_async_operation_runs_with_await : AsyncSpecs
       () => Result.Should().Be("result");
   }
 
-  [Subject(typeof(TaskSpecificationExtensions), "exception")]
-  public class when_an_async_operation_fails_without_await : AsyncSpecs
-  {
-    static Exception exception;
-
-    Because of = () => exception = Catch.Exception(() => Delayed.Fail());
-
-    It should_not_capture_the_exception =
-      () => exception.Should().BeNull();
-  }
-
   [Subject(typeof(TaskSpecificationExtensions), "exception")]
   public class when_a_single_async_operation_fails_with_await : AsyncSpecs
   {
@@ -90,4 +79,4 @@ public class AsyncSpecs
   {
   }
 }
-#endif
+#endif

src/Machine.Specifications/Catch.cs

@@ -1,30 +1,71 @@
 using System;
+#if !NET35 && !NET40
+using System.Threading.Tasks;
+#endif
 
 namespace Machine.Specifications
 {
     public static class Catch
     {
         public static Exception Exception(Action throwingAction)
         {
-            return Only<Exception>(throwingAction);
+            try
+            {
+                throwingAction();
+            }
+            catch (Exception ex)
+            {
+                return ex;
+            }
+
+            return null;
         }
 
         public static Exception Exception<T>(Func<T> throwingFunc)
         {
+#if !NET35 && !NET40
+            Task task;
+#endif
             try
             {
-                throwingFunc();
+                var result = throwingFunc();
+#if !NET35 && !NET40
+                task = result as Task;
+#endif
             }
             catch (Exception exception)
             {
                 return exception;
             }
-
+#if !NET35 && !NET40
+            if (task != null)
+            {
+                throw new InvalidOperationException("You must use Catch.ExceptionAsync for async methods");
+            }
+#endif
             return null;
         }
 
+#if !NET35 && !NET40
+        public static async Task<Exception> ExceptionAsync(Func<Task> throwingAction)
+        {
+            Exception exception = null;
+
+            try
+            {
+                await throwingAction();
+            }
+            catch (Exception ex)
+            {
+                exception = ex;
+            }
+
+            return exception;
+        }
+#endif
+
         public static TException Only<TException>(Action throwingAction)
-          where TException : Exception
+            where TException : Exception
         {
             try
             {