FIX: Add get_caller_fqn() function

fqn_decorators/decorators.py

@@ -1,5 +1,6 @@
 # -*- coding: utf-8 -*-
 import functools
+import inspect
 import sys
 
 
@@ -31,6 +32,64 @@ def get_fqn(obj):
     return '.'.join(filter(None, path))
 
 
+def get_caller_fqn():
+    """
+    Use this method inside the function/method to get the fully qualified name (FQN) of its caller.
+    Works for methods and functions including inner ones.
+
+    E.g. consider module 'src.check_fqn':
+      def parent():
+          internal()
+
+      def internal():
+          get_caller_fqn()
+
+      parent()  # Returns FQN of the method that called 'internal()': 'src.check_fqn.parent'
+
+    For complex nested inner functions FQN will represent a stack trace of calls (only for Python3):
+      def inside():
+          def child_method():
+              return get_caller_fqn()
+
+          def outer_method():
+              return child_method()
+
+          class Caller:
+              def parent_with_inner(self):
+                  def inner_parent():
+                      return outer_method()
+                  return inner_parent()
+
+          return Caller().parent_with_inner()
+
+      inside()  # Returns 'src.check_fqn.inside.Caller.parent_with_inner.inner_parent.outer_method'
+    """
+    stack_depth = len(inspect.stack())
+    depth = 2  # 0: current method, 1: method that uses this function, 2: actual caller
+    function_name = None
+    while depth < stack_depth:
+        caller_frame = inspect.stack()[depth]
+        try:
+            frame, caller_function = caller_frame.frame, caller_frame.function
+        except AttributeError:  # old Python versions
+            frame, caller_function = caller_frame[0], caller_frame[3]
+        # If caller is a function
+        try:
+            return get_fqn(frame.f_globals[caller_function])
+        except KeyError:
+            pass
+        # If caller is a class method
+        function_name = '.'.join(filter(None, [caller_function, function_name]))  # Handle nested inner calls
+        try:
+            return '{}.{}'.format(get_fqn(frame.f_locals['self'].__class__), function_name)
+        except KeyError:
+            pass
+        # We are called from internal method we can't obtain reference to, e.g. list comprehension or nested inner
+        # functions -> try to go one level up the stack
+        depth += 1
+    return ''
+
+
 class Decorator(object):
     """
     A base class to easily create decorators.

tests/conftest.py

@@ -1,2 +1,9 @@
+import sys
+
+collect_ignore = ["setup.py"]
+if sys.version_info[0] < 3:
+    collect_ignore.append("test_fqn_decorators_asynchronous.py")
+
+
 def pytest_configure():
     pass

tests/test_fqn_decorators.py

@@ -1,6 +1,7 @@
 #!/usr/bin/env python
 # -*- coding: utf-8 -*-
 import functools
+import sys
 
 import fqn_decorators
 import mock
@@ -43,6 +44,71 @@ def test_decorated_class(self):
         assert fqn_decorators.get_fqn(examples.A) == 'tests.examples.A'
 
 
+class TestGetCallerFqn:
+    def test_function(self):
+        def inline_method():
+            return fqn_decorators.get_caller_fqn()
+
+        assert inline_method() == 'tests.test_fqn_decorators.TestGetCallerFqn.test_function'
+
+    def test_method(self):
+        class Inline:
+            def inline(self):
+                return fqn_decorators.get_caller_fqn()
+
+        assert Inline().inline() == 'tests.test_fqn_decorators.TestGetCallerFqn.test_method'
+
+    @pytest.mark.skipif(sys.version_info < (3, 0), reason='requires python3')
+    def test_caller_is_method(self):
+        def inline_method():
+            return fqn_decorators.get_caller_fqn()
+
+        class Caller:
+            def parent(self):
+                return inline_method()
+
+        assert Caller().parent() == (
+            'tests.test_fqn_decorators.TestGetCallerFqn.test_caller_is_method.Caller.parent'
+        )
+
+    def test_caller_is_inner(self):
+        def child_method():
+            return fqn_decorators.get_caller_fqn()
+
+        def parent_method():
+            return child_method()
+
+        assert parent_method() == (
+            'tests.test_fqn_decorators.TestGetCallerFqn.test_caller_is_inner.parent_method'
+        )
+
+    @pytest.mark.skipif(sys.version_info < (3, 0), reason='requires python3')
+    def test_caller_is_complex(self):
+        def child_method():
+            return fqn_decorators.get_caller_fqn()
+
+        def outer_method():
+            return child_method()
+
+        class Caller:
+            def parent(self):
+                return outer_method()
+
+            def parent_with_inner(self):
+                def inner_parent():
+                    return outer_method()
+                return inner_parent()
+
+        assert Caller().parent() == (
+            'tests.test_fqn_decorators.TestGetCallerFqn.test_caller_is_complex.Caller.parent.outer_method'
+        )
+
+        assert Caller().parent_with_inner() == (
+            'tests.test_fqn_decorators.TestGetCallerFqn.test_caller_is_complex.'
+            'Caller.parent_with_inner.inner_parent.outer_method'
+        )
+
+
 class TestDecorator(object):
 
     def test_getattr(self):

tox.ini

@@ -13,12 +13,6 @@ deps =
     -rrequirements/requirements-base.txt
     -rrequirements/requirements-testing.txt
 
-[testenv:py27]
-setenv =
-    PYTEST_ADDOPTS = --ignore tests/test_fqn_decorators_asynchronous.py
-deps =
-    {[testenv]deps}
-
 [testenv:lint]
 basepython = python3.5
 commands = flake8 decorators tests --exclude=fqn_decorators/__init__.py