Rewrote the VersionAndBranchFinder tests so they do actual file system work, since AppVeyor don't seem to agree with local test running in that everything is green. Not trying to fake it may be a better solution anyhow.

Ref https://ci.appveyor.com/project/GitTools/gitversion/build/3.3.1-PullRequest.711+28%20(Build%20458)

Author: asbjornu

src/GitVersionTask.Tests/VersionAndBranchFinderTests.cs

@@ -9,6 +9,13 @@
 
 #endregion
 
+using System;
+using System.Collections.Concurrent;
+using System.Text;
+
+using GitVersion;
+using GitVersion.Helpers;
+
 using NUnit.Framework;
 
 using Shouldly;
@@ -17,10 +24,9 @@
 public class VersionAndBranchFinderTests
 {
     [Test]
-    public void ExistingCacheFile()
+    public void CacheFileExistsOnDisk()
     {
-        var fileSystem = new TestFileSystem();
-        fileSystem.WriteAllText("existing\\gitversion_cache\\C7B23F8A47ECE0E14CBE2E22C04269CC5A88E275.yml", @"
+        const string versionCacheFileContent = @"
 Major: 4
 Minor: 10
 Patch: 3
@@ -43,21 +49,92 @@ public void ExistingCacheFile()
 CommitsSinceVersionSource: 19
 CommitsSinceVersionSourcePadded: 0019
 CommitDate: 2015-11-10
-");
+";
+
+        var infoBuilder = new StringBuilder();
+        Action<string> infoLogger = s => { infoBuilder.AppendLine(s); };
+
+        Logger.SetLoggers(infoLogger, null, null);
+
+        using (var fixture = new EmptyRepositoryFixture(new Config()))
+        {
+            var fileSystem = new FileSystem();
+            fixture.Repository.MakeACommit();
+            var vv = VersionAndBranchFinder.GetVersion(fixture.RepositoryPath, null, false, fileSystem);
+
+            vv.AssemblySemVer.ShouldBe("0.1.0.0");
+
+            vv.FileName.ShouldNotBeNullOrEmpty();
+
+            fileSystem.WriteAllText(vv.FileName, versionCacheFileContent);
+
+            // I would rather see that VersionAndBranchFinder was non-static and could be reinstantiated to
+            // clear the in-memory cache, but that's not the case, so I have to perform this ugly hack. @asbjornu
+            VersionAndBranchFinder.VersionCacheVersions = new ConcurrentDictionary<string, VersionVariables>();
+
+            vv = VersionAndBranchFinder.GetVersion(fixture.RepositoryPath, null, false, fileSystem);
+
+            vv.AssemblySemVer.ShouldBe("4.10.3.0");
+        }
+
+        var info = infoBuilder.ToString();
+
+        Console.WriteLine(info);
+
+        info.ShouldContain("Deserializing version variables from cache file", () => info);
+    }
+
+
+    [Test]
+    public void CacheFileExistsInMemory()
+    {
+        var infoBuilder = new StringBuilder();
+        Action<string> infoLogger = s => { infoBuilder.AppendLine(s); };
+
+        Logger.SetLoggers(infoLogger, null, null);
+
+        using (var fixture = new EmptyRepositoryFixture(new Config()))
+        {
+            var fileSystem = new FileSystem();
+            fixture.Repository.MakeACommit();
+            var vv = VersionAndBranchFinder.GetVersion(fixture.RepositoryPath, null, false, fileSystem);
 
-        var vv = VersionAndBranchFinder.GetVersion("existing", null, false, fileSystem);
+            vv.AssemblySemVer.ShouldBe("0.1.0.0");
 
-        vv.AssemblySemVer.ShouldBe("4.10.3.0");
+            vv.FileName.ShouldNotBeNullOrEmpty();
+
+            vv = VersionAndBranchFinder.GetVersion(fixture.RepositoryPath, null, false, fileSystem);
+
+            vv.AssemblySemVer.ShouldBe("0.1.0.0");
+        }
+
+        var info = infoBuilder.ToString();
+
+        Console.WriteLine(info);
+
+        info.ShouldContain("yml not found", () => info);
+        info.ShouldNotContain("Deserializing version variables from cache file", () => info);
     }
 
 
     [Test]
-    public void MissingCacheFile()
+    public void CacheFileIsMissing()
     {
-        var fileSystem = new TestFileSystem();
+        var infoBuilder = new StringBuilder();
+        Action<string> infoLogger = s => { infoBuilder.AppendLine(s); };
+
+        Logger.SetLoggers(infoLogger, null, null);
+
+        using (var fixture = new EmptyRepositoryFixture(new Config()))
+        {
+            fixture.Repository.MakeACommit();
+            var fileSystem = new FileSystem();
+            var vv = VersionAndBranchFinder.GetVersion(fixture.RepositoryPath, null, false, fileSystem);
 
-        var vv = VersionAndBranchFinder.GetVersion("missing", null, false, fileSystem);
+            vv.AssemblySemVer.ShouldBe("0.1.0.0");
+        }
 
-        vv.AssemblySemVer.ShouldBe("0.1.0.0");
+        var info = infoBuilder.ToString();
+        info.ShouldContain("yml not found", () => info);
     }
 }