Story SW-300: add classes to test the std output from python UnitTest

framework

.gitattributes

@@ -1830,6 +1830,7 @@ LCU/Maintenance/MDB_tools/cli/probe_mdb.py -text
 LCU/Maintenance/MDB_tools/deploy.sh -text
 LCU/Maintenance/MDB_tools/fabfile.py -text
 LCU/Maintenance/MDB_tools/requirements.txt -text
+LCU/Maintenance/MDB_tools/test/output_testing.py -text
 LCU/Maintenance/MDB_tools/test/python-coverage.sh eol=lf
 LCU/Maintenance/MDB_tools/test/t_mdb_loader.in.test_rtsm.data -text
 LCU/Maintenance/MDB_tools/test/t_mdb_loader.in.test_stationtest.data -text

LCU/Maintenance/MDB_tools/test/CMakeLists.txt

@@ -7,3 +7,4 @@ file(COPY
 lofar_add_test(t_mdb_loader)
 lofar_add_test(t_probe_mdb)
 
+

LCU/Maintenance/MDB_tools/test/output_testing.py

+# coding=utf-8
+import mock
+
+try:
+    from StringIO import StringIO
+except ImportError:
+    from io import StringIO
+
+
+class compare_output_with:
+    """
+    This class purpose is to create a 'with' environment to assert that the output is equal to the one specified
+    in the class constructor
+    """
+
+    def __init__(self, expected_stdout):
+        """
+        Class constructor takes a path to a text file that contains the expected std output
+        :param expected_stdout: expected standard output
+        :type expected_stdout: str
+        """
+        self.expected_stdout = expected_stdout
+
+    def __enter__(self):
+        self.stdout_patcher = mock.patch('sys.stdout', new=StringIO())
+        self.stdout_patcher.start()
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        stdout_produced = self.stdout_patcher.target.stdout.getvalue()
+        self.stdout_patcher.stop()
+
+        assert self.expected_stdout == stdout_produced, \
+            "expected stdout {} differs from {}".format(repr(self.expected_stdout), repr(stdout_produced))
+
+
+class compare_output_with_file_content(compare_output_with):
+    """
+        This class purpose is to create a 'with' environment to assert that the output is equal to the one specified
+        in content of the file_path specified in the class constructor
+    """
+
+    def __init__(self, file_path):
+        """
+        Class constructor takes a path to a text file that contains the expected std output
+        :param file_path: path to the file containing the expected standard output
+        """
+        try:
+            with open(file_path, 'r') as fstream_in:
+                content = fstream_in.read()
+        except IOError as e:
+            raise Exception('Cannot run test  - IOError on file {}: {}'.format(file_path, e))
+
+        super(compare_output_with_file_content, self).__init__(content)
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