Tests deprication warnings

[Hellseher]

Hi,

During packaging your project for Guix I've noticed pytest deprication warnings:

• python-pytest version: 6.2.5

guix describe
Generation 279  May 13 2022 15:28:57    (current)
  guix 7f7cc04
    repository URL: https://git.savannah.gnu.org/git/guix.git
    branch: master
    commit: 7f7cc042083a759f9b136761f8f9f95ed87563ed

Warnings

=============================== warnings summary ===============================
ometa/test/test_builder.py::PythonWriterTests::test_markAsTree
 /tmp/guix-build-python-parsley-1.3.drv-0/source/ometa/test/test_builder.py:328: DeprecationWarning: Please use assertTrue instead.
   self.assert_("\n        tree = True\n" in writePython(g, ""))

ometa/test/test_protocol.py::ParserProtocolTestCase::test_connectionEstablishes
 /tmp/guix-build-python-parsley-1.3.drv-0/source/ometa/test/test_protocol.py:93: DeprecationWarning: Please use assertTrue instead.
   self.assert_(self.protocol.receiver.connected)

ometa/test/test_protocol.py::ParserProtocolTestCase::test_dataIgnoredAfterDisconnection
 /tmp/guix-build-python-parsley-1.3.drv-0/source/ometa/test/test_protocol.py:190: DeprecationWarning: Please use assertTrue instead.
   self.assert_(not transport.aborted)

ometa/test/test_protocol.py::ParserProtocolTestCase::test_exceptionsRaisedFromReceiver
 /tmp/guix-build-python-parsley-1.3.drv-0/source/ometa/test/test_protocol.py:177: DeprecationWarning: Please use assertNotEqual instead.
   self.failIfEqual(self.protocol.receiver.lossReason, None)

ometa/test/test_protocol.py::ParserProtocolTestCase::test_exceptionsRaisedFromReceiver
 /tmp/guix-build-python-parsley-1.3.drv-0/source/ometa/test/test_protocol.py:180: DeprecationWarning: Please use assertTrue instead.
   self.assert_(transport.aborted)

ometa/test/test_protocol.py::ParserProtocolTestCase::test_parseFailure
 /tmp/guix-build-python-parsley-1.3.drv-0/source/ometa/test/test_protocol.py:164: DeprecationWarning: Please use assertNotEqual instead.
   self.failIfEqual(self.protocol.receiver.lossReason, None)

ometa/test/test_protocol.py::ParserProtocolTestCase::test_parseFailure
 /tmp/guix-build-python-parsley-1.3.drv-0/source/ometa/test/test_protocol.py:167: DeprecationWarning: Please use assertTrue instead.
   self.assert_(transport.aborted)

ometa/test/test_pymeta.py::MakeGrammarTest::test_brokenGrammar
 /tmp/guix-build-python-parsley-1.3.drv-0/source/ometa/test/test_pymeta.py:1141: DeprecationWarning: Please use assertEqual instead.
   self.assertEquals(e.position, 57)

ometa/test/test_pymeta.py::MakeGrammarTest::test_brokenGrammar
 /tmp/guix-build-python-parsley-1.3.drv-0/source/ometa/test/test_pymeta.py:1142: DeprecationWarning: Please use assertEqual instead.
   self.assertEquals(e.error, [("message", "end of input")])

ometa/test/test_runtime.py::RuntimeTests::test_exactlyFail
 /tmp/guix-build-python-parsley-1.3.drv-0/source/ometa/test/test_runtime.py:57: DeprecationWarning: Please use assertEqual instead.
   self.assertEquals(exc.args[1], expected(None, "g"))

ometa/test/test_runtime.py::RuntimeTests::test_exactlyFail
 /tmp/guix-build-python-parsley-1.3.drv-0/source/ometa/test/test_runtime.py:58: DeprecationWarning: Please use assertEqual instead.
   self.assertEquals(exc.args[0], 0)

-- Docs: https://docs.pytest.org/en/stable/warnings.html
================= 307 passed, 8 skipped, 11 warnings in 5.17s ==================