Separate Terraform's tool-dependent tests into a new Calamari.ExternalTools.Tests project

build/Build.PackageCalamariProjects.cs

@@ -23,7 +23,13 @@ public partial class Build
 
                            //its assumed each project has a corresponding test project
                            var testProjectNames = projectNames.Select(f => $"{f}.Tests");
-                           var allProjectNames = projectNames.Concat(testProjectNames).ToHashSet();
+
+                           // Calamari.ExternalTools.Tests has no corresponding non-test flavour - it's a standalone
+                           // test project covering tools (Terraform, etc.) that need a real external CLI binary.
+                           // Included here (rather than via the flavour+".Tests" convention above) purely so it
+                           // gets published/zipped for the nightly TestCalamariExternalTools build to consume -
+                           // it is never run as part of this (default) pipeline.
+                           var allProjectNames = projectNames.Concat(testProjectNames).Append("Calamari.ExternalTools.Tests").ToHashSet();
 
                            var calamariProjects = Solution.Projects
                                                           .Where(project => allProjectNames.Contains(project.Name))

build/Build.TestCalamariExternalTools.cs

@@ -0,0 +1,21 @@
+using JetBrains.Annotations;
+
+namespace Calamari.Build;
+
+partial class Build
+{
+    [PublicAPI]
+    Target TestCalamariExternalTools =>
+        target => target
+            .Executes(async () =>
+                      {
+                          var dotnetPath = await LocateOrInstallDotNetSdk();
+
+                          // Runs against a real external CLI tool (e.g. terraform), downloaded or found on PATH -
+                          // not part of the default per-commit pipeline, invoked as its own nightly/on-demand build.
+                          CreateTestRun("CalamariTests/Calamari.ExternalTools.Tests.dll")
+                              .WithDotNetPath(dotnetPath)
+                              .WithFilter("TestCategory=ExternalTool")
+                              .Execute();
+                      });
+}