Show how to test an application using LibGit2Sharp in isolation

1 files changed, 71 insertions, 0 deletions

diff --git a/LibGit2Sharp.Tests/MockedRepositoryFixture.cs b/LibGit2Sharp.Tests/MockedRepositoryFixture.cs
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+++ b/LibGit2Sharp.Tests/MockedRepositoryFixture.cs
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+using System.Collections.Generic;
+using System;
+using System.Linq;
+using LibGit2Sharp.Tests.TestHelpers;
+using Xunit;
+using Moq;
+
+namespace LibGit2Sharp.Tests
+{
+    // This fixture shows how one can mock the IRepository when writing an application against LibGit2Sharp.
+    // The application we want to test is simulated by the CommitCounter class (see below), which takes an IRepository,
+    // and whose role is to compute and return the number of commits in the given repository.
+    public class MockedRepositoryFixture : BaseFixture
+    {
+        // In this test, we pass to CommitCounter a concrete instance of the Repository. It means we will end up calling the concrete Repository
+        // during the test run.
+        [Fact]
+        public void CanCountCommitsWithConcreteRepository()
+        {
+            using (var repo = new Repository(BareTestRepoPath))
+            {
+                var commitCounter = new CommitCounter(repo);
+                Assert.Equal(7, commitCounter.NumberOfCommits);
+            }
+        }
+
+        // This test shows that CommitCounter can take a mocked instance of IRepository. It means we can test CommitCounter without
+        // relying on the concrete repository. We are testing CommitCounter in isolation.
+        [Fact]
+        public void CanCountCommitsWithMockedRepository()
+        {
+            var commitLog = Mock.Of<CommitLog>(cl => cl.GetEnumerator() == FakeCommitLog(17));
+            var repo = Mock.Of<IRepository>(r => r.Commits == commitLog);
+
+            var commitCounter = new CommitCounter(repo);
+            Assert.Equal(17, commitCounter.NumberOfCommits);
+        }
+
+        private static IEnumerator<Commit> FakeCommitLog(int size)
+        {
+            for (int i = 0; i < size; i++)
+            {
+                yield return FakeCommit(Guid.NewGuid().ToString());
+            }
+        }
+
+        private static Commit FakeCommit(string sha)
+        {
+            var commitMock = new Mock<Commit>();
+            commitMock.SetupGet(x => x.Sha).Returns(sha);
+
+            return commitMock.Object;
+        }
+
+        // Simulated external application ;)
+        private class CommitCounter
+        {
+            private readonly IRepository repo;
+
+            public CommitCounter(IRepository repo)
+            {
+                this.repo = repo;
+            }
+
+            public int NumberOfCommits
+            {
+                get { return repo.Commits.Count(); }
+            }
+        }
+    }
+}