8th day of python challenges 111-117

venv/lib/python3.6/site-packages/pandas/tests/test_optional_dependency.py

@@ -0,0 +1,52 @@
+import sys
+import types
+
+import pytest
+
+from pandas.compat._optional import VERSIONS, import_optional_dependency
+
+import pandas.util.testing as tm
+
+
+def test_import_optional():
+    match = "Missing .*notapackage.* pip .* conda .* notapackage"
+    with pytest.raises(ImportError, match=match):
+        import_optional_dependency("notapackage")
+
+    result = import_optional_dependency("notapackage", raise_on_missing=False)
+    assert result is None
+
+
+def test_xlrd_version_fallback():
+    pytest.importorskip("xlrd")
+    import_optional_dependency("xlrd")
+
+
+def test_bad_version():
+    name = "fakemodule"
+    module = types.ModuleType(name)
+    module.__version__ = "0.9.0"
+    sys.modules[name] = module
+    VERSIONS[name] = "1.0.0"
+
+    match = "Pandas requires .*1.0.0.* of .fakemodule.*'0.9.0'"
+    with pytest.raises(ImportError, match=match):
+        import_optional_dependency("fakemodule")
+
+    with tm.assert_produces_warning(UserWarning):
+        result = import_optional_dependency("fakemodule", on_version="warn")
+    assert result is None
+
+    module.__version__ = "1.0.0"  # exact match is OK
+    result = import_optional_dependency("fakemodule")
+    assert result is module
+
+
+def test_no_version_raises():
+    name = "fakemodule"
+    module = types.ModuleType(name)
+    sys.modules[name] = module
+    VERSIONS[name] = "1.0.0"
+
+    with pytest.raises(ImportError, match="Can't determine .* fakemodule"):
+        import_optional_dependency(name)