set up python unit test infrastructure

Extract boostraping code from convwatch.py to unotest.py. Use python builtin
unittest module as unit test framework. Specify the unit test modules in make
file. Another option would be to use discover mode of unittest module.

Add __pycache__ to global .gitignore to keep the source directory clean.
Another option would be to deliver the unit tests to workdir prior to test
execution.

Currently only system python3 is supported.

Change-Id: I2692817673f786e950e1176a17c7675f989755b6
Reviewed-on: https://gerrit.libreoffice.org/3214
Reviewed-by: David Ostrovsky <David.Ostrovsky@gmx.de>
Tested-by: David Ostrovsky <David.Ostrovsky@gmx.de>

sw/qa/unoapi/python/get_expression.py

@@ -0,0 +1,53 @@
+import unittest
+from org.libreoffice.unotest import UnoConnection
+
+class TestGetExpression(unittest.TestCase):
+    _unoCon = None
+    _xDoc = None
+
+    @classmethod
+    def setUpClass(cls):
+        cls._unoCon = UnoConnection({})
+        cls._unoCon.setUp()
+        cls._xDoc = cls._unoCon.openEmptyWriterDoc()
+
+    @classmethod
+    def tearDownClass(cls):
+        cls._unoCon.tearDown()
+
+    def test_get_expression(self):
+        self.__class__._unoCon.checkProperties(
+            self.__class__._xDoc.createInstance("com.sun.star.text.textfield.GetExpression"),
+            {"Content": "foo",
+             "CurrentPresentation": "bar",
+             "NumberFormat": 0,
+             "IsShowFormula": False,
+             "SubType": 0,
+             "VariableSubtype": 1,
+             "IsFixedLanguage": False,
+             },
+            self
+            )
+
+    # property 'Value' is read only?
+    @unittest.expectedFailure
+    def test_get_expression_veto_read_only(self):
+        self.__class__._unoCon.checkProperties(
+            self.__class__._xDoc.createInstance("com.sun.star.text.textfield.GetExpression"),
+            {"Value": 0.0},
+            self
+            )
+
+    # property 'NumberingType' is unknown?
+    @unittest.expectedFailure
+    def test_get_expression_unknown_property(self):
+        self.__class__._unoCon.checkProperties(
+            self.__class__._xDoc.createInstance("com.sun.star.text.textfield.GetExpression"),
+            {"NumberingType": 0},
+            self
+            )
+
+
+if __name__ == '__main__':
+    unittest.main()
+