(build) Fix unit tests

As a result of changes to "how" a release is found from GitHub, it is
no longer the case that an exception is thrown, but rather, if a
specific release can't be found, it simply returns a null value. The
unit tests were updated to reflect this change in functionality.

Author: gep13

src/GitReleaseManager.Core.Tests/Provider/GitHubProviderTests.cs

@@ -631,30 +631,26 @@ public async Task Should_Get_Release()
             var result = await _gitHubProvider.GetReleaseAsync(OWNER, REPOSITORY, TAG_NAME).ConfigureAwait(false);
             result.ShouldBeSameAs(release);
 
-            await _gitHubClient.Repository.Release.Received(1).Get(OWNER, REPOSITORY, TAG_NAME).ConfigureAwait(false);
+            await _gitHubClient.Repository.Release.Received(1).GetAll(OWNER, REPOSITORY).ConfigureAwait(false);
             _mapper.Received(1).Map<Release>(Arg.Any<object>());
         }
 
         [Test]
-        public async Task Should_Throw_An_Exception_On_Getting_Release_For_Non_Existent_Tag()
+        public async Task Should_Return_Null_On_Getting_Release_For_Non_Existent_Tag()
         {
             _gitHubClient.Repository.Release.Get(OWNER, REPOSITORY, TAG_NAME)
                 .Returns(Task.FromException<Octokit.Release>(_notFoundException));
 
-            var ex = await Should.ThrowAsync<NotFoundException>(() => _gitHubProvider.GetReleaseAsync(OWNER, REPOSITORY, TAG_NAME)).ConfigureAwait(false);
-            ex.Message.ShouldBe(_notFoundException.Message);
-            ex.InnerException.ShouldBe(_notFoundException);
+            var release = await _gitHubProvider.GetReleaseAsync(OWNER, REPOSITORY, TAG_NAME).ConfigureAwait(false);
+
+            release.ShouldBeNull();
         }
 
         [Test]
-        public async Task Should_Throw_An_Exception_On_Getting_Release()
+        public async Task Should_Return_Null_Getting_Release()
         {
-            _gitHubClient.Repository.Release.Get(OWNER, REPOSITORY, TAG_NAME)
-                .Returns(Task.FromException<Octokit.Release>(_exception));
-
-            var ex = await Should.ThrowAsync<ApiException>(() => _gitHubProvider.GetReleaseAsync(OWNER, REPOSITORY, TAG_NAME)).ConfigureAwait(false);
-            ex.Message.ShouldBe(_exception.Message);
-            ex.InnerException.ShouldBe(_exception);
+            var release = await _gitHubProvider.GetReleaseAsync(OWNER, REPOSITORY, TAG_NAME).ConfigureAwait(false);
+            release.ShouldBeNull();
         }
 
         [Test]

src/GitReleaseManager.Core.Tests/VcsServiceTests.cs

@@ -302,7 +302,7 @@ public async Task Should_Create_Release_From_Milestone()
                 .Returns(Task.FromResult(RELEASE_NOTES));
 
             _vcsProvider.GetReleaseAsync(OWNER, REPOSITORY, MILESTONE_TITLE)
-                .Returns(Task.FromException<Release>(_notFoundException));
+                .Returns(Task.FromResult<Release>(null));
 
             _vcsProvider.CreateReleaseAsync(OWNER, REPOSITORY, Arg.Any<Release>())
                 .Returns(Task.FromResult(release));
@@ -330,7 +330,7 @@ public async Task Should_Create_Release_From_Milestone_Using_Template_File()
                 .Returns(Task.FromResult(RELEASE_NOTES));
 
             _vcsProvider.GetReleaseAsync(OWNER, REPOSITORY, MILESTONE_TITLE)
-                .Returns(Task.FromException<Release>(_notFoundException));
+                .Returns(Task.FromResult<Release>(null));
 
             _vcsProvider.CreateReleaseAsync(OWNER, REPOSITORY, Arg.Any<Release>())
                 .Returns(Task.FromResult(release));
@@ -434,7 +434,7 @@ public async Task Should_Create_Release_From_InputFile()
             var release = new Release();
 
             _vcsProvider.GetReleaseAsync(OWNER, REPOSITORY, MILESTONE_TITLE)
-                .Returns(Task.FromException<Release>(_notFoundException));
+                .Returns(Task.FromResult<Release>(null));
 
             _vcsProvider.CreateReleaseAsync(OWNER, REPOSITORY, Arg.Any<Release>())
                 .Returns(Task.FromResult(release));