Avoid duplicate ctest runs during Github CI runs

Fixes microsoft#196

build.cake

@@ -29,6 +29,11 @@ string ObjectDirectory
  }
 }
 
+bool IsRunningInGithub()
+{
+ return !string.IsNullOrEmpty(EnvironmentVariable<string>("GITHUB_WORKFLOW", ""));
+}
+
 var MsBuildSettings = new DotNetCoreMSBuildSettings { MaxCpuCount = 0 };
 
 //
@@ -303,6 +308,7 @@ Task("Binplace-CMake")
 
 Task("Test-CMake")
  .WithCriteria(() => IsRunningOnUnix())
+ .WithCriteria(() => !IsRunningInGithub()) // github pipelines already test this via `make cmake-test`
  .IsDependentOn("Binplace-CMake")
  .Does(() =>
  {
@@ -327,6 +333,8 @@ Task("Test-CMake")
  });
 
 
+// This does *almost* the same thing as Test-CMake but using the Mlos.TestRun.proj to invoke the tests instead of ctest.
+//
 Task("Run-CMake-UnitTests")
  .IsDependentOn("Binplace-CMake")
  .WithCriteria(() => IsRunningOnUnix())