[PackageMetadata] Multiple top levels

Another corner cases: packages that have multiple top levels.

For example Zope2 package has quite a few top levels,
that's why you can import Products.OFSP without any mention to Zope2 on
the import line (I guess).

CHANGES.rst

@@ -4,8 +4,8 @@ Changelog of z3c.dependencychecker
 2.4 (unreleased)
 ----------------
 
-- Nothing changed yet.
-
+- Handle packages that have multiple top levels, i.e. packages like Zope2.
+  [gforcada]
 
 2.3 (2018-06-21)
 ----------------

z3c/dependencychecker/package.py

@@ -167,11 +167,29 @@ def top_level(self):
         )
 
         if os.path.exists(sources_top_level):
-            return sources_top_level
+            return sources_top_level,  # note that is a tuple
 
         single_module_top_level = '{0}.py'.format(sources_top_level)
         if os.path.exists(single_module_top_level):
-            return single_module_top_level
+            return single_module_top_level,  # note that is a tuple
+
+        top_levels = []
+        for possible_top_level in content.split('\n'):
+            sources_top_level = os.path.join(
+                self.package_dir,
+                possible_top_level,
+            )
+            if os.path.exists(sources_top_level):
+                logger.debug('Found top level %s', sources_top_level)
+                top_levels.append(sources_top_level)
+            else:
+                logger.warning(
+                    'Top level %s not found but referenced '
+                    'by top_level.txt',
+                    possible_top_level,
+                )
+        if top_levels:
+            return top_levels
 
         logger.error(
             '%s does not exist but %s%stop_level.txt points there.\n'
@@ -237,16 +255,20 @@ def set_user_mappings(self):
                 self.imports.add_user_mapping(package, packages_provided)
 
     def analyze_package(self):
-        top_folder = self.metadata.top_level
-        for module_obj in MODULES:
-            logger.debug("Starting analyzing files using %s...", module_obj)
-            for source_file in module_obj.create_from_files(top_folder):
+        for top_folder in self.metadata.top_level:
+            logger.debug("Analyzing package top_level %s...", top_folder)
+            for module_obj in MODULES:
                 logger.debug(
-                    'Searching dependencies (with %s) in file %s...',
-                    module_obj.__name__,
-                    source_file.path,
+                    "Starting analyzing files using %s...",
+                    module_obj,
                 )
-                self.imports.add_imports(source_file.scan())
+                for source_file in module_obj.create_from_files(top_folder):
+                    logger.debug(
+                        'Searching dependencies (with %s) in file %s...',
+                        module_obj.__name__,
+                        source_file.path,
+                    )
+                    self.imports.add_imports(source_file.scan())
 
     def _load_user_config(self):
         config_file_path = os.sep.join([

z3c/dependencychecker/tests/test_package_metadata.py

@@ -282,7 +282,7 @@ def test_top_level_txt_file_found(minimal_structure):
     path, package_name = minimal_structure
     metadata = PackageMetadata(path)
 
-    assert metadata.top_level == os.path.join(path, package_name)
+    assert metadata.top_level == (os.path.join(path, package_name), )
 
 
 def test_no_top_level_txt_file_found(minimal_structure):
@@ -337,4 +337,31 @@ def test_top_level_is_module(minimal_structure):
 
     metadata = PackageMetadata(path)
 
-    assert metadata.top_level == top_level_module_path
+    assert metadata.top_level == (top_level_module_path, )
+
+
+def test_top_level_multiple(minimal_structure):
+    path, package_name = minimal_structure
+    top_level_file = os.path.join(
+        path,
+        '{0}.egg-info'.format(package_name),
+        'top_level.txt',
+    )
+    with open(top_level_file, 'w') as top_level:
+        top_level.write('one\n')
+        top_level.write('two\n')
+        top_level.write('three\n')
+
+    top_level_folders = [
+        '{0}/one'.format(path),
+        '{0}/two'.format(path),
+        '{0}/three'.format(path),
+    ]
+    for new_top_level in top_level_folders:
+        os.makedirs(new_top_level)
+
+    metadata = PackageMetadata(path)
+
+    assert metadata.top_level == (
+        top_level_folders
+    )