First test and mocking attempt

.gitignore

@@ -166,3 +166,5 @@ fabric.properties
 [Ss]cripts
 pyvenv.cfg
 pip-selfcheck.json
+
+.pytest_cache/

src/requirements-test.txt

@@ -0,0 +1,2 @@
+pytest>=3.7.2,<3.8
+pytest-mock>=1.10.0,<1.11

src/test/test_configuration_file_discovery.py

@@ -0,0 +1,21 @@
+import os
+
+import pytest
+from _pytest.monkeypatch import MonkeyPatch
+
+from rs500common.configuration import discover_config_file_by_name
+
+
+def test_discovery(monkeypatch: MonkeyPatch):
+    def mock(path):
+        return True
+    with monkeypatch.context() as m:
+        m.setattr(os.path, 'isfile', mock)
+        m.setattr(os.path, 'exists', mock)
+        result = discover_config_file_by_name('test.ini', '/foo/bar')
+    assert result == os.path.join('/foo/bar', 'test.ini')
+
+
+def test_no_hit():
+    with pytest.raises(FileNotFoundError):
+        discover_config_file_by_name('does-not-exist.nothing', 'bla-blubb')