Force evaluation before test execution

This makes error it so error messages from the build are not wrapped in
error messages for tests.

Before this change the build is performed lazily when the tests try to
interact with the rootfs under test making it appear like a build
failure is a test error when in reality we didn't even get to the test.

Signed-off-by: Brian Goff <cpuguy83@gmail.com>

frontend/azlinux/handle_rpm.go

@@ -49,6 +49,10 @@ func handleRPM(w worker) gwclient.BuildFunc {
 				return nil, nil, err
 			}
 
+			if err := ref.Evaluate(ctx); err != nil {
+				return ref, nil, err
+			}
+
 			if imgRef, err := runTests(ctx, client, w, spec, sOpt, st, targetKey, pg); err != nil {
 				// return the container ref in case of error so it can be used to debug
 				// the installed package state.

frontend/jammy/handle_deb.go

@@ -49,6 +49,10 @@ func handleDeb(ctx context.Context, client gwclient.Client) (*gwclient.Result, e
 			return nil, nil, err
 		}
 
+		if err := ref.Evaluate(ctx); err != nil {
+			return ref, nil, err
+		}
+
 		if ref, err := runTests(ctx, client, spec, sOpt, st, targetKey, opt); err != nil {
 			cfg, _ := buildImageConfig(ctx, client, spec, platform, targetKey)
 			return ref, cfg, err

frontend/test_runner.go

@@ -41,6 +41,14 @@ func RunTests(ctx context.Context, client gwclient.Client, spec *dalec.Spec, ref
 		return nil
 	}
 
+	if err := ref.Evaluate(ctx); err != nil {
+		// Force evaluation here so that any errors for the build itself can surface
+		// more cleanly.
+		// Otherwise an error for something wrong in the build (e.g. a failed compilation)
+		// will look like an error in a test (or all tests).
+		return err
+	}
+
 	ctr, err := ref.ToState()
 	if err != nil {
 		return err