When(...).Throws gives a CouldNotSetReturnDueToNoLastCallException (#803)

src/NSubstitute/Core/WhenCalled.cs

@@ -7,6 +7,9 @@ namespace NSubstitute.Core;
 
 public class WhenCalled<T>(ISubstitutionContext context, T substitute, Action<T> call, MatchArgs matchArgs)
 {
+    private const string RecommendedThrowMethodToUseMessage =
+        "The recommended method to use is Throw().";
+
     private readonly ICallRouter _callRouter = context.GetCallRouterFor(substitute!);
     private readonly IThreadLocalContext _threadContext = context.ThreadContext;
     private readonly IRouteFactory _routeFactory = context.RouteFactory;
@@ -70,4 +73,25 @@ public void Throw(Exception exception) =>
     /// </summary>
     public void Throw(Func<CallInfo, Exception> createException) =>
         Do(ci => throw createException(ci));
+
+    /// <summary>
+    /// Throws the specified exception when called.
+    /// </summary>
+    [Obsolete(RecommendedThrowMethodToUseMessage)]
+    public void Throws(Exception exception) =>
+        Throw(exception);
+
+    /// <summary>
+    /// Throws an exception of the given type when called.
+    /// </summary>
+    [Obsolete(RecommendedThrowMethodToUseMessage)]
+    public TException Throws<TException>() where TException : Exception, new()
+        => Throw<TException>();
+
+    /// <summary>
+    /// Throws an exception generated by the specified function when called.
+    /// </summary>
+    [Obsolete(RecommendedThrowMethodToUseMessage)]
+    public void Throws(Func<CallInfo, Exception> createException) =>
+        Throw(createException);
 }

tests/NSubstitute.Acceptance.Specs/WhenCalledDo.cs

@@ -80,6 +80,19 @@ public void Throw_exception_when_Throw_with_generic_exception()
         Assert.That(called, Is.EqualTo(1));
     }
 
+    [Test]
+    public void Throw_exception_when_Throws_with_generic_exception()
+    {
+        int called = 0;
+        _something.When(x => x.Echo(Arg.Any<int>())).Do(x => called++);
+        var expectedException = _something.When(x => x.Echo(Arg.Any<int>())).Throws<ArgumentException>();
+
+        Assert.That(called, Is.EqualTo(0), "Should not have been called yet");
+        ArgumentException actualException = Assert.Throws<ArgumentException>(() => _something.Echo(1234));
+        Assert.That(actualException, Is.EqualTo(expectedException));
+        Assert.That(called, Is.EqualTo(1));
+    }
+
     [Test]
     public void Throw_exception_when_Throw_with_specific_exception()
     {
@@ -94,6 +107,20 @@ public void Throw_exception_when_Throw_with_specific_exception()
         Assert.That(called, Is.EqualTo(1));
     }
 
+    [Test]
+    public void Throw_exception_when_Throws_with_specific_exception()
+    {
+        var exception = new IndexOutOfRangeException("Test");
+        int called = 0;
+        _something.When(x => x.Echo(Arg.Any<int>())).Do(x => called++);
+        _something.When(x => x.Echo(Arg.Any<int>())).Throws(exception);
+
+        Assert.That(called, Is.EqualTo(0), "Should not have been called yet");
+        IndexOutOfRangeException thrownException = Assert.Throws<IndexOutOfRangeException>(() => _something.Echo(1234));
+        Assert.That(thrownException, Is.EqualTo(exception));
+        Assert.That(called, Is.EqualTo(1));
+    }
+
     [Test]
     public void Throw_exception_when_Throw_with_exception_generator()
     {
@@ -108,6 +135,20 @@ public void Throw_exception_when_Throw_with_exception_generator()
         Assert.That(called, Is.EqualTo(1));
     }
 
+    [Test]
+    public void Throw_exception_when_Throws_with_exception_generator()
+    {
+        Func<CallInfo, Exception> createException = ci => new ArgumentException("Argument: " + ci.Args()[0]);
+        int called = 0;
+        _something.When(x => x.Echo(Arg.Any<int>())).Do(x => called++);
+        _something.When(x => x.Echo(Arg.Any<int>())).Throws(createException);
+
+        Assert.That(called, Is.EqualTo(0), "Should not have been called yet");
+        ArgumentException thrownException = Assert.Throws<ArgumentException>(() => _something.Echo(1234));
+        Assert.That(thrownException.Message, Is.EqualTo("Argument: 1234"));
+        Assert.That(called, Is.EqualTo(1));
+    }
+
     [Test]
     public async Task Can_configure_async_methods_nicely()
     {