Add test which verifies #257 is fixed

Author: JakeGinnivan

src/GitVersionExe.Tests/AssemblyInfoFileUpdateTests.cs

@@ -91,6 +91,41 @@ public void ShouldReplaceAssemblyVersionWithStar()
         {
             const string expected = @"AssemblyVersion(""2.3.0.0"");
 AssemblyInformationalVersion(""2.3.1+3.Branch.foo.Sha.hash"");
+AssemblyFileVersion(""2.3.1.0"");";
+            fileSystem.Received().WriteAllText("C:\\Testing\\AssemblyInfo.cs", expected);
+        }
+    }
+
+    [Test] public void ShouldReplaceAlreadySubstitutedValues()
+    {
+        var fileSystem = Substitute.For<IFileSystem>();
+        var version = new SemanticVersion
+        {
+            BuildMetaData = new SemanticVersionBuildMetaData(3, "foo", "hash", DateTimeOffset.Now),
+            Major = 2,
+            Minor = 3,
+            Patch = 1
+        };
+
+        const string workingDir = "C:\\Testing";
+        const string assemblyInfoFile = @"AssemblyVersion(""2.2.0.0"");
+AssemblyInformationalVersion(""2.2.0+5.Branch.foo.Sha.hash"");
+AssemblyFileVersion(""2.2.0.0"");";
+
+        fileSystem.Exists("C:\\Testing\\AssemblyInfo.cs").Returns(true);
+        fileSystem.ReadAllText("C:\\Testing\\AssemblyInfo.cs").Returns(assemblyInfoFile);
+
+        var config = new TestEffectiveConfiguration(assemblyVersioningScheme: AssemblyVersioningScheme.MajorMinor);
+        var variable = VariableProvider.GetVariablesFor(version, config, false);
+        var args = new Arguments
+        {
+            UpdateAssemblyInfo = true,
+            UpdateAssemblyInfoFileName = "AssemblyInfo.cs"
+        };
+        using (new AssemblyInfoFileUpdate(args, workingDir, variable, fileSystem))
+        {
+            const string expected = @"AssemblyVersion(""2.3.0.0"");
+AssemblyInformationalVersion(""2.3.1+3.Branch.foo.Sha.hash"");
 AssemblyFileVersion(""2.3.1.0"");";
             fileSystem.Received().WriteAllText("C:\\Testing\\AssemblyInfo.cs", expected);
         }