chore: display "script" output on failure without diffing

cmd/nixtest/display.go

@@ -19,13 +19,12 @@ func printErrors(results Results) {
 				continue
 			}
 			fmt.Println(text.FgRed.Sprintf("⚠ Test \"%s\" failed:", result.Spec.Name))
-			var message string
-			if result.Status == StatusFailure {
+			var message string = result.ErrorMessage
+			// if ErrorMessage is set, prefer that
+			if result.Status == StatusFailure && message == "" {
 				dmp := diffmatchpatch.New()
 				diffs := dmp.DiffMain(result.Expected, result.Actual, false)
 				message = fmt.Sprintf("Diff:\n%s", dmp.DiffPrettyText(diffs))
-			} else {
-				message = result.ErrorMessage
 			}
 
 			// handle multi-line colored changes

cmd/nixtest/junit.go

@@ -88,6 +88,9 @@ func GenerateJUnitReport(name string, results Results) (string, error) {
 			if result.Status == StatusFailure {
 				suite.Failures++
 				report.Failures++
+				if result.ErrorMessage != "" {
+					testCase.Failure = &result.ErrorMessage
+				} else {
 					// FIXME: ComputeEdits deprecated
 					edits := myers.ComputeEdits(result.Expected, result.Actual)
 					diff, err := textdiff.ToUnified("expected", "actual", result.Expected, edits, 3)
@@ -97,6 +100,7 @@ func GenerateJUnitReport(name string, results Results) (string, error) {
 					// remove newline hint
 					diff = strings.ReplaceAll(diff, "\\ No newline at end of file\n", "")
 					testCase.Failure = &diff
+				}
 			} else if result.Status == StatusError {
 				suite.Errors++
 				report.Errors++

cmd/nixtest/main.go

@@ -212,8 +212,12 @@ func runTest(spec TestSpec) TestResult {
 			result.Status = StatusError
 			result.ErrorMessage = fmt.Sprintf("[system] failed to run script: %v", err.Error())
 		}
-		expected = ""
-		actual = fmt.Sprintf("[exit code %d]\n[Stdout]\n%s\n[Stderr]\n%s", exitCode, stdout.String(), stderr.String())
+		if exitCode != 0 {
+			result.Status = StatusFailure
+			result.ErrorMessage = fmt.Sprintf("[exit code %d]\n[stdout]\n%s\n[stderr]\n%s", exitCode, stdout.String(), stderr.String())
+		}
+		// no need for equality checking with "script"
+		goto end
 	} else {
 		log.Panic().Str("type", spec.Type).Msg("Invalid test type")
 	}