support/testing: test_octave.py: use assertRunNotOk()

Use the helper to simplify the test.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

support/testing/tests/package/test_octave.py

@@ -51,8 +51,7 @@ class TestOctave(infra.basetest.BRTest):
 
         # Check octave can fail
         cmd = self.octave_cmd("assert(false)")
-        _, exit_code = self.emulator.run(cmd)
-        self.assertNotEqual(exit_code, 0)
+        self.assertRunNotOk(cmd)
 
         # Check string output
         string = "Hello World"