Add unit test prior to refactoring

test/Nerdbank.GitVersioning.Tests/CommandTests.cs

@@ -0,0 +1,40 @@
+// Copyright (c) .NET Foundation and Contributors. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using Nerdbank.GitVersioning;
+using Nerdbank.GitVersioning.Commands;
+using Xunit;
+
+public class CommandTests : RepoTestBase
+{
+    private readonly TestOutputHelperToTextWriterAdapter adapter;
+
+    public CommandTests(ITestOutputHelper logger)
+        : base(logger)
+    {
+        this.adapter = new(logger);
+    }
+
+    // TODO: This is tightly coupled to the cloud build service. Can I use a FakeCloudBuildService instead?
+    [Theory]
+    [InlineData("VisualStudioTeamServices")]
+    [InlineData("TeamCity")]
+    [InlineData("Jenkins")]
+    public void CloudCommand_BuildNumber(string ciSystem)
+    {
+        var outWriter = new StringWriter();
+        var errWriter = new StringWriter();
+
+        var command = new CloudCommand(outWriter, errWriter);
+
+        command.SetBuildVariables(this.RepoPath, metadata: [], version: "1.2.3.4", ciSystem, allVars: false, commonVars: false, additionalVariables: [], alwaysUseLibGit2: false);
+
+        outWriter.Flush();
+        errWriter.Flush();
+        Assert.NotEmpty(outWriter.ToString());
+        Assert.Empty(errWriter.ToString());
+    }
+
+    protected override GitContext CreateGitContext(string path, string committish = null)
+        => GitContext.Create(path, committish, engine: GitContext.Engine.ReadWrite);
+}