test/infamy: add optional msg support to tap.py::Test.fail()

A very common pattern in our tests is:

  if (condition):
    print(f"the condition failed with {output}")
    test.fail()

This change allows us to write:

  if (condition):
    test.fail(f"the condition failed with {output}")

Signed-off-by: Joachim Wiberg <[email protected]>

Author: troglobit

test/infamy/tap.py

@@ -95,7 +95,10 @@ def succeed(self):
     def skip(self):
         raise TestSkip()
 
-    def fail(self):
+    def fail(self, message=None):
+        if message:
+            self.out.write(f"# {message}\n")
+            self.out.flush()
         raise TestFail()