StepHarness needs a strict error policy for it to exercise what we want in the tests.

Author: nedtwigg

testlib/src/main/java/com/diffplug/spotless/StepHarness.java

@@ -46,6 +46,7 @@ public static StepHarness forSteps(FormatterStep... steps) {
 				.lineEndingsPolicy(LineEnding.UNIX.createPolicy())
 				.encoding(StandardCharsets.UTF_8)
 				.rootDir(Paths.get(""))
+				.exceptionPolicy(new FormatExceptionPolicyStrict())
 				.build());
 	}
 

testlib/src/main/java/com/diffplug/spotless/StepHarnessWithFile.java

@@ -42,6 +42,7 @@ public static StepHarnessWithFile forStep(ResourceHarness harness, FormatterStep
 				.lineEndingsPolicy(LineEnding.UNIX.createPolicy())
 				.steps(Collections.singletonList(step))
 				.rootDir(harness.rootFolder().toPath())
+				.exceptionPolicy(new FormatExceptionPolicyStrict())
 				.build());
 	}