Fix/test empty image check (#3087)

* test(run): add check for empty image in TestRun_CorrectImage

* typo

Author: intojhanurag

cmd/run_test.go

@@ -334,7 +334,9 @@ func TestRun_CorrectImage(t *testing.T) {
 			runner := mock.NewRunner()
 
 			runner.RunFn = func(_ context.Context, f fn.Function, _ string, _ time.Duration) (*fn.Job, error) {
-				// TODO: add if for empty image? -- should fail beforehand
+				if f.Build.Image == "" {
+					return nil, fmt.Errorf("Image is empty, should fail before running")
+				}
 				if f.Build.Image != tt.image {
 					return nil, fmt.Errorf("Expected image: %v but got: %v", tt.image, f.Build.Image)
 				}