fix #10 undo the genral py.test hack

add a opt-in
add a auto-opt-in for the py.test module

Author: RonnyPfannschmidt

src/apipkg/__init__.py

@@ -180,8 +180,32 @@ def __dict__(self):
         return dict
 
 
-def AliasModule(modname, modpath, attrname=None):
+def _py_test_hack(modpath, attrname, importerror_alternative):
+    if (
+        modpath == "pytest"
+        and attrname is None
+        and importerror_alternative is ImportError
+    ):
+        return None
+    else:
+        return importerror_alternative
+
+
+def _alias_mod_repr(modname, modpath, attrname, importerror_alternative):
+    x = modpath
+    if attrname:
+        x += "." + attrname
+    if importerror_alternative is not ImportError:
+        return "<AliasModule {!r} for {!r} alternative {!r}>".format(
+            modname, x, importerror_alternative
+        )
+    else:
+        return "<AliasModule {!r} for {!r}>".format(modname, x)
+
+
+def AliasModule(modname, modpath, attrname=None, importerror_alternative=ImportError):
     mod = []
+    importerror_alternative = _py_test_hack(modpath, attrname, importerror_alternative)
 
     def getmod():
         if not mod:
@@ -191,18 +215,20 @@ def getmod():
             mod.append(x)
         return mod[0]
 
+    repr_result = _alias_mod_repr(modname, modpath, attrname, importerror_alternative)
+
     class AliasModule(ModuleType):
         def __repr__(self):
-            x = modpath
-            if attrname:
-                x += "." + attrname
-            return "<AliasModule {!r} for {!r}>".format(modname, x)
+            return repr_result
 
         def __getattribute__(self, name):
             try:
                 return getattr(getmod(), name)
             except ImportError:
-                return None
+                if importerror_alternative is ImportError:
+                    raise
+                else:
+                    return importerror_alternative
 
         def __setattr__(self, name, value):
             setattr(getmod(), name, value)

test_apipkg.py

@@ -551,13 +551,35 @@ def test_aliasmodule_aliases_an_attribute():
     assert not hasattr(am, "lqkje")
 
 
-def test_aliasmodule_aliases_unimportable():
+def test_aliasmodule_aliases_unimportable_fails():
     am = apipkg.AliasModule("mymod", "qlwkejqlwe", "main")
     r = repr(am)
     assert "<AliasModule 'mymod' for 'qlwkejqlwe.main'>" == r
+    # this would pass starting with apipkg 1.3 to work around a pytest bug
+    with pytest.raises(ImportError):
+        am.qwe is None
+
+
+def test_aliasmodule_aliases_unimportable_can_return_none():
+    am = apipkg.AliasModule("mymod", "qlwkejqlwe", "main", None)
+    r = repr(am)
+    assert "<AliasModule 'mymod' for 'qlwkejqlwe.main' alternative None>" == r
+    # this would pass starting with apipkg 1.3 to work around a pytest bug
     assert am.qwe is None
 
 
+def test_aliasmodule_pytest_autoreturn_none_for_hack(monkeypatch):
+    def error(*k):
+        raise ImportError(k)
+
+    monkeypatch.setattr(apipkg, "importobj", error)
+    # apipkg 1.3 added this hack
+    am = apipkg.AliasModule("mymod", "pytest")
+    r = repr(am)
+    assert "<AliasModule 'mymod' for 'pytest' alternative None>" == r
+    assert am.test is None
+
+
 def test_aliasmodule_unicode():
     am = apipkg.AliasModule(u"mymod", "pprint")
     assert am