[DjangoSettings] Scan python files

Scan settings.py files searching for some Django specific entries where dependencies can hide in.

z3c/dependencychecker/modules.py

@@ -2,6 +2,7 @@
 from xml.etree import ElementTree
 from z3c.dependencychecker.dotted_name import DottedName
 import ast
+import fnmatch
 import os
 import re
 
@@ -366,11 +367,81 @@ def scan(self):
                             yield dotted_name
 
 
+class DjangoSettings(PythonModule):
+    """Extract imports from Django settings.py
+
+    These files are used to enable Django components.
+    """
+
+    @classmethod
+    def search_files(cls, top_dir):
+        """Find all settings.py files in the package
+
+        For that it gets the path to where top_level.txt points to,
+        which is not always a folder:
+        - folder example: z3c.dependencychecker itself
+        - file example: flake8-isort or any other single file distribution
+
+        Return this very same class, which would allow to call the scan()
+        method to get an iterator over all this file's imports.
+        """
+        if top_dir.endswith('.py'):
+            return
+
+        for path, folders, filenames in os.walk(top_dir):
+            for filename in filenames:
+                if fnmatch.fnmatch(filename, '*settings.py'):
+                    yield cls(
+                        top_dir,
+                        os.path.join(path, filename),
+                    )
+
+    def scan(self):
+        for node in ast.walk(self._get_tree()):
+            if isinstance(node, ast.Assign):
+                if self._is_installed_apps_assignment(node):
+                    if isinstance(node.value, (ast.Tuple, ast.List)):
+                        for element in node.value.elts:
+                            if isinstance(element, ast.Str):
+                                yield DottedName(
+                                    element.s,
+                                    file_path=self.path,
+                                    is_test=self.testing,
+                                )
+
+                if self._is_test_runner_assignment(node):
+                    if isinstance(node.value, ast.Str):
+                        yield DottedName(
+                            node.value.s,
+                            file_path=self.path,
+                            is_test=True,
+                        )
+
+    @staticmethod
+    def _is_installed_apps_assignment(node):
+        if len(node.targets) == 1 and \
+                isinstance(node.targets[0], ast.Name) and \
+                node.targets[0].id == 'INSTALLED_APPS':
+            return True
+
+        return False
+
+    @staticmethod
+    def _is_test_runner_assignment(node):
+        if len(node.targets) == 1 and \
+                isinstance(node.targets[0], ast.Name) and \
+                node.targets[0].id == 'TEST_RUNNER':
+            return True
+
+        return False
+
+
 MODULES = (
     PythonModule,
     ZCMLFile,
     FTIFile,
     GSMetadata,
     PythonDocstrings,
     DocFiles,
+    DjangoSettings,
 )

z3c/dependencychecker/tests/test_modules_django_settings.py

@@ -0,0 +1,149 @@
+# -*- coding: utf-8 -*-
+from z3c.dependencychecker.modules import DjangoSettings
+from z3c.dependencychecker.tests.utils import write_source_file_at
+import os
+import tempfile
+
+
+RANDOM_CODE = 'from zope.component import adapter'
+RANDOM_ASSIGNMENT = 'a = 3'
+APPS_ASSIGNMENT_TO_STRING = 'INSTALLED_APPS = "random"'
+APPS_ASSIGNMENT_TO_TUPLE = 'INSTALLED_APPS = ("random1", "random2", )'
+APPS_ASSIGNMENT_TO_LIST = 'INSTALLED_APPS = ["random3", "random4", ]'
+APPS_ASSIGNMENT_TO_LIST_MIXED = 'INSTALLED_APPS = ["random5", 3, ]'
+TEST_RUNNER_ASSIGNMENT_TO_LIST = 'TEST_RUNNER = ["random6", "random7", ]'
+TEST_RUNNER_ASSIGNMENT_TO_STRING = 'TEST_RUNNER = "random8"'
+
+
+def _get_imports_of_python_module(folder, source):
+    temporal_file = write_source_file_at(
+        (folder.strpath, ),
+        source_code=source,
+    )
+
+    django_settings = DjangoSettings(folder.strpath, temporal_file)
+    dotted_names = [x.name for x in django_settings.scan()]
+    return dotted_names
+
+
+def test_search_files_nothing(minimal_structure):
+    path, package_name = minimal_structure
+    modules_found = [x for x in DjangoSettings.search_files(path)]
+    assert len(modules_found) == 0
+
+
+def test_search_files_single_file_random_name():
+    _, tmp_file = tempfile.mkstemp('.py')
+    modules_found = [x for x in DjangoSettings.search_files(tmp_file)]
+    assert len(modules_found) == 0
+
+
+def test_search_files_single_file_settings_name(minimal_structure):
+    path, package_name = minimal_structure
+    src_path = os.path.join(path, 'src')
+    write_source_file_at([src_path, ], filename='some_settings.py', )
+    modules_found = [x for x in DjangoSettings.search_files(src_path)]
+    assert len(modules_found) == 1
+
+
+def test_search_files_deep_nested(minimal_structure):
+    path, package_name = minimal_structure
+    src_path = os.path.join(path, 'src')
+    write_source_file_at(
+        [src_path, 'a', 'b', 'c', ],
+        filename='anothersettings.py',
+    )
+    modules_found = [x for x in DjangoSettings.search_files(src_path)]
+    assert len(modules_found) == 1
+
+
+def test_random_code(tmpdir):
+    dotted_names = _get_imports_of_python_module(tmpdir, RANDOM_CODE)
+    assert len(dotted_names) == 0
+
+
+def test_random_assignment(tmpdir):
+    dotted_names = _get_imports_of_python_module(tmpdir, RANDOM_ASSIGNMENT)
+    assert len(dotted_names) == 0
+
+
+def test_apps_assignment_to_string(tmpdir):
+    dotted_names = _get_imports_of_python_module(
+        tmpdir,
+        APPS_ASSIGNMENT_TO_STRING,
+    )
+    assert len(dotted_names) == 0
+
+
+def test_apps_assignment_to_tuple(tmpdir):
+    dotted_names = _get_imports_of_python_module(
+        tmpdir,
+        APPS_ASSIGNMENT_TO_TUPLE,
+    )
+    assert len(dotted_names) == 2
+
+
+def test_apps_assignment_to_tuple_details(tmpdir):
+    dotted_names = _get_imports_of_python_module(
+        tmpdir,
+        APPS_ASSIGNMENT_TO_TUPLE,
+    )
+    assert 'random1' in dotted_names
+    assert 'random2' in dotted_names
+
+
+def test_apps_assignment_to_list(tmpdir):
+    dotted_names = _get_imports_of_python_module(
+        tmpdir,
+        APPS_ASSIGNMENT_TO_LIST,
+    )
+    assert len(dotted_names) == 2
+
+
+def test_apps_assignment_to_list_details(tmpdir):
+    dotted_names = _get_imports_of_python_module(
+        tmpdir,
+        APPS_ASSIGNMENT_TO_LIST,
+    )
+    assert 'random3' in dotted_names
+    assert 'random4' in dotted_names
+
+
+def test_apps_assignment_to_list_mixed(tmpdir):
+    dotted_names = _get_imports_of_python_module(
+        tmpdir,
+        APPS_ASSIGNMENT_TO_LIST_MIXED,
+    )
+    assert len(dotted_names) == 1
+
+
+def test_apps_assignment_to_list_mixed_details(tmpdir):
+    dotted_names = _get_imports_of_python_module(
+        tmpdir,
+        APPS_ASSIGNMENT_TO_LIST_MIXED,
+    )
+    assert dotted_names[0] == 'random5'
+
+
+def test_runner_assignment_to_list(tmpdir):
+    dotted_names = _get_imports_of_python_module(
+        tmpdir,
+        TEST_RUNNER_ASSIGNMENT_TO_LIST,
+    )
+    assert len(dotted_names) == 0
+
+
+def test_runner_assignment_to_string(tmpdir):
+    dotted_names = _get_imports_of_python_module(
+        tmpdir,
+        TEST_RUNNER_ASSIGNMENT_TO_STRING,
+    )
+    assert len(dotted_names) == 1
+
+
+def test_apps_assignment_to_string_mixed_details(tmpdir):
+    dotted_names = _get_imports_of_python_module(
+        tmpdir,
+        TEST_RUNNER_ASSIGNMENT_TO_STRING,
+    )
+    assert dotted_names[0] == 'random8'