Merge pull request #663 from Socolin/throws-async

Add `.ThrowsAsync()` that will correctly mock exception on async methods

Author: dtchepak

CHANGELOG.md

@@ -1,3 +1,6 @@
+### unreleased
+* [NEW] Add `.ThrowsAsync()` that will correctly mock exception on async methods. (#609)
+
 ### 4.3.0 (Jan 2021)
 
 * [NEW] Add .NET 5 (#636) and .NET 6 (#674) support. Thanks to @zvirja and @Havunen!
@@ -55,7 +58,7 @@ See [BreakingChanges.md](BreakingChanges.md) if you are still using pre-C#7. (#4
 * [NEW] `Configure()` extension in `NSubstitute.Extensions.ConfigurationExtensions` to
 ensure NSubstitute handles the next call as a configuration/specification. (#350, @zvirja)
 * [UPDATE] Performance improvements. (@zvirja)
-    - `CallResults` performance optimisation 
+    - `CallResults` performance optimisation
     - Delegate proxy generation improvements (#362)
     - Minimise allocations and LINQ use on hot code paths (#390)
     - Optimise array allocation (#395)
@@ -67,7 +70,7 @@ This helps fix some problems with overlapping configurations. See #345 and
 
 #### New and improved debugging, errors and error messages
 
-* [NEW] Raise `CouldNotConfigureBaseMethodException` when trying to configure a call to 
+* [NEW] Raise `CouldNotConfigureBaseMethodException` when trying to configure a call to
 call a base method that does not exist. (#429, @zvirja)
 * [NEW] Raise `RedundantArgumentMatcherException` if extra arg matchers are detected. This is
 a huge help for immediately identifying misconfigured tests. (@zvirja)
@@ -85,7 +88,7 @@ Including (but not limited to):
 * [FIX] Improved handling of virtual calls in constructors. (#423, @zvirja)
 * [NEW] Added a set of `When()` overloads to configure async methods without compilation warnings. (#468, @zvirja)
 * [FIX] Fixed potential for `ArgumentNullException` on finalizer thread. (#382, @zvirja)
-* [UPDATE] Now using Castle.Core 4.3.1+. We :heart: you Castle.Core! (Thanks for the 
+* [UPDATE] Now using Castle.Core 4.3.1+. We :heart: you Castle.Core! (Thanks for the
 PR Alexandr Nikitin!)
 * [NEW] Expose `.Received(Quantity)` in `NSubstitute.ReceivedExtensions` namespace. Thanks to
 @firelizzard18 for this suggestion.
@@ -131,7 +134,7 @@ Ian Johnson (@ipjohnson) for this change. (#303)
 * [UPDATE] .NET Core build is now signed, which removes a warning when
 referencing .NET standard library. Thanks to Connie Yau (@conniey) for
 this change. (#302)
-* [FIX] Removed redundant .NET standard dependencies when referencing 
+* [FIX] Removed redundant .NET standard dependencies when referencing
 NSubstitute as a .NET Framework library. Thanks to Alex Povar (@zvirja). (#295)
 
 ### 2.0.2 (February 2017)

src/NSubstitute/Extensions/ExceptionExtensions.cs

@@ -1,4 +1,7 @@
 using System;
+using System.Linq;
+using System.Reflection;
+using System.Threading.Tasks;
 using NSubstitute.Core;
 
 // Disable nullability for client API, so it does not affect clients.
@@ -67,5 +70,197 @@ public static ConfiguredCall ThrowsForAnyArgs<TException>(this object value)
         /// <returns></returns>
         public static ConfiguredCall ThrowsForAnyArgs(this object value, Func<CallInfo, Exception> createException) =>
             value.ReturnsForAnyArgs(ci => throw createException(ci));
+
+        /// <summary>
+        /// Throw an exception for this call.
+        /// </summary>
+        /// <param name="value"></param>
+        /// <param name="ex">Exception to throw</param>
+        /// <returns></returns>
+        public static ConfiguredCall ThrowsAsync(this Task value, Exception ex) =>
+            value.Returns(_ => TaskFromException(ex));
+
+        /// <summary>
+        /// Throw an exception for this call.
+        /// </summary>
+        /// <param name="value"></param>
+        /// <param name="ex">Exception to throw</param>
+        /// <returns></returns>
+        public static ConfiguredCall ThrowsAsync<T>(this Task<T> value, Exception ex) =>
+            value.Returns(_ => TaskFromException<T>(ex));
+
+        /// <summary>
+        /// Throw an exception of the given type for this call.
+        /// </summary>
+        /// <typeparam name="TException">Type of exception to throw</typeparam>
+        /// <param name="value"></param>
+        /// <returns></returns>
+        public static ConfiguredCall ThrowsAsync<TException>(this Task value)
+            where TException : notnull, Exception, new()
+        {
+            return value.Returns(_ => FromException(value, new TException()));
+        }
+
+        /// <summary>
+        /// Throw an exception for this call, as generated by the specified function.
+        /// </summary>
+        /// <param name="value"></param>
+        /// <param name="createException">Func creating exception object</param>
+        /// <returns></returns>
+        public static ConfiguredCall ThrowsAsync(this Task value, Func<CallInfo, Exception> createException) =>
+            value.Returns(ci => TaskFromException(createException(ci)));
+
+        /// <summary>
+        /// Throw an exception for this call, as generated by the specified function.
+        /// </summary>
+        /// <param name="value"></param>
+        /// <param name="createException">Func creating exception object</param>
+        /// <returns></returns>
+        public static ConfiguredCall ThrowsAsync<T>(this Task<T> value, Func<CallInfo, Exception> createException) =>
+            value.Returns(ci => TaskFromException<T>(createException(ci)));
+
+        /// <summary>
+        /// Throw an exception for this call made with any arguments.
+        /// </summary>
+        /// <param name="value"></param>
+        /// <param name="ex">Exception to throw</param>
+        /// <returns></returns>
+        public static ConfiguredCall ThrowsAsyncForAnyArgs(this Task value, Exception ex) =>
+            value.ReturnsForAnyArgs(_ => TaskFromException(ex));
+
+        /// <summary>
+        /// Throw an exception for this call made with any arguments.
+        /// </summary>
+        /// <param name="value"></param>
+        /// <param name="ex">Exception to throw</param>
+        /// <returns></returns>
+        public static ConfiguredCall ThrowsAsyncForAnyArgs<T>(this Task<T> value, Exception ex) =>
+            value.ReturnsForAnyArgs(_ => TaskFromException<T>(ex));
+
+        /// <summary>
+        /// Throws an exception of the given type for this call made with any arguments.
+        /// </summary>
+        /// <typeparam name="TException">Type of exception to throw</typeparam>
+        /// <param name="value"></param>
+        /// <returns></returns>
+        public static ConfiguredCall ThrowsAsyncForAnyArgs<TException>(this Task value)
+            where TException : notnull, Exception, new()
+        {
+            return value.ReturnsForAnyArgs(_ => FromException(value, new TException()));
+        }
+
+        /// <summary>
+        /// Throws an exception for this call made with any arguments, as generated by the specified function.
+        /// </summary>
+        /// <param name="value"></param>
+        /// <param name="createException">Func creating exception object</param>
+        /// <returns></returns>
+        public static ConfiguredCall ThrowsAsyncForAnyArgs(this Task value, Func<CallInfo, Exception> createException) =>
+            value.ReturnsForAnyArgs(ci => TaskFromException(createException(ci)));
+
+        /// <summary>
+        /// Throws an exception for this call made with any arguments, as generated by the specified function.
+        /// </summary>
+        /// <param name="value"></param>
+        /// <param name="createException">Func creating exception object</param>
+        /// <returns></returns>
+        public static ConfiguredCall ThrowsAsyncForAnyArgs<T>(this Task<T> value, Func<CallInfo, Exception> createException) =>
+            value.ReturnsForAnyArgs(ci => TaskFromException<T>(createException(ci)));
+
+#if NET5_0_OR_GREATER
+        /// <summary>
+        /// Throw an exception for this call.
+        /// </summary>
+        /// <param name="value"></param>
+        /// <param name="ex">Exception to throw</param>
+        /// <returns></returns>
+        public static ConfiguredCall ThrowsAsync<T>(this ValueTask<T> value, Exception ex) =>
+            value.Returns(_ => ValueTask.FromException<T>(ex));
+
+        /// <summary>
+        /// Throw an exception of the given type for this call.
+        /// </summary>
+        /// <typeparam name="TResult">Type of exception to throw</typeparam>
+        /// <typeparam name="TException">Type of exception to throw</typeparam>
+        /// <param name="value"></param>
+        /// <returns></returns>
+        public static ConfiguredCall ThrowsAsync<TResult, TException>(this ValueTask<TResult> value)
+            where TException : notnull, Exception, new()
+        {
+            return value.Returns(_ => ValueTask.FromException<TResult>(new TException()));
+        }
+
+        /// <summary>
+        /// Throw an exception for this call, as generated by the specified function.
+        /// </summary>
+        /// <param name="value"></param>
+        /// <param name="createException">Func creating exception object</param>
+        /// <returns></returns>
+        public static ConfiguredCall ThrowsAsync<T>(this ValueTask<T> value, Func<CallInfo, Exception> createException) =>
+            value.Returns(ci => ValueTask.FromException<T>(createException(ci)));
+
+        /// <summary>
+        /// Throws an exception of the given type for this call made with any arguments.
+        /// </summary>
+        /// <typeparam name="T"></typeparam>
+        /// <typeparam name="TException">Type of exception to throw</typeparam>
+        /// <param name="value"></param>
+        /// <returns></returns>
+        public static ConfiguredCall ThrowsAsyncForAnyArgs<T, TException>(this ValueTask<T> value)
+            where TException : notnull, Exception, new()
+        {
+            return value.ReturnsForAnyArgs(_ => ValueTask.FromException<T>(new TException()));
+        }
+
+        /// <summary>
+        /// Throw an exception for this call made with any arguments.
+        /// </summary>
+        /// <param name="value"></param>
+        /// <param name="ex">Exception to throw</param>
+        /// <returns></returns>
+        public static ConfiguredCall ThrowsAsyncForAnyArgs<T>(this ValueTask<T> value, Exception ex) =>
+            value.ReturnsForAnyArgs(_ => ValueTask.FromException<T>(ex));
+
+        /// <summary>
+        /// Throws an exception for this call made with any arguments, as generated by the specified function.
+        /// </summary>
+        /// <param name="value"></param>
+        /// <param name="createException">Func creating exception object</param>
+        /// <returns></returns>
+        public static ConfiguredCall ThrowsAsyncForAnyArgs<T>(this ValueTask<T> value, Func<CallInfo, Exception> createException) =>
+            value.ReturnsForAnyArgs(ci => ValueTask.FromException<T>(createException(ci)));
+#endif
+
+        private static object FromException(object value, Exception exception)
+        {
+            // Handle Task<T>
+            var valueType = value.GetType();
+            if (valueType.IsConstructedGenericType)
+            {
+                var fromExceptionMethodInfo = typeof(Task).GetMethods(BindingFlags.Static | BindingFlags.Public).Single(m => m.Name == "FromException" && m.ContainsGenericParameters);
+                var specificFromExceptionMethod = fromExceptionMethodInfo.MakeGenericMethod(valueType.GenericTypeArguments);
+                return specificFromExceptionMethod.Invoke(null, new object[] {exception});
+            }
+
+            return TaskFromException(exception);
+        }
+
+        private static Task TaskFromException(Exception ex)  {
+#if NET45
+            return new Task(() => throw ex);
+#else
+            return Task.FromException(ex);
+#endif
+        }
+
+        private static Task<T> TaskFromException<T>(Exception ex)
+        {
+#if NET45
+            return new Task<T>(() => throw ex);
+#else
+            return Task<T>.FromException<T>(ex);
+#endif
+        }
+
     }
 }

tests/NSubstitute.Acceptance.Specs/Infrastructure/ISomething.cs

@@ -19,14 +19,17 @@ public interface ISomething
 
         object this[string key] { get; set; }
         System.Threading.Tasks.Task Async();
+        System.Threading.Tasks.Task DoAsync(object stuff);
         System.Threading.Tasks.Task<int> CountAsync();
+        System.Threading.Tasks.Task<int> AnythingAsync(object stuff);
         System.Threading.Tasks.Task<string> EchoAsync(int i);
         System.Threading.Tasks.Task<string> SayAsync(string s);
         System.Threading.Tasks.Task<SomeClass> SomeActionAsync();
         System.Threading.Tasks.Task<SomeClass> SomeActionWithParamsAsync(int i, string s);
 
         System.Threading.Tasks.ValueTask<int> CountValueTaskAsync();
         System.Threading.Tasks.ValueTask<string> EchoValueTaskAsync(int i);
+        System.Threading.Tasks.ValueTask<int> AnythingValueTaskAsync(object stuff);
         System.Threading.Tasks.ValueTask<string> SayValueTaskAsync(string s);
         System.Threading.Tasks.ValueTask<SomeClass> SomeActionValueTaskAsync();
         System.Threading.Tasks.ValueTask<SomeClass> SomeActionWithParamsValueTaskAsync(int i, string s);