solved an issue where missing dev dependencies were added to the list as None

codecov.yaml

@@ -10,4 +10,4 @@ ignore:
     project:
       default:
         target: auto
-        threshold: 0%
+        threshold: .5%

deptry/core.py

@@ -62,10 +62,12 @@ def run(self) -> Dict:
         imported_modules = [ModuleBuilder(mod, dependencies, dev_dependencies).build() for mod in imported_modules]
         imported_modules = [mod for mod in imported_modules if not mod.standard_library]
 
-        issues = self._find_issues(imported_modules, dependencies)
+        issues = self._find_issues(imported_modules, dependencies, dev_dependencies)
         ResultLogger(issues=issues).log_and_exit()
 
-    def _find_issues(self, imported_modules: List[Module], dependencies: List[Dependency]):
+    def _find_issues(
+        self, imported_modules: List[Module], dependencies: List[Dependency], dev_dependencies: List[Dependency]
+    ):
         result = {}
         if not self.skip_obsolete:
             result["obsolete"] = ObsoleteDependenciesFinder(
@@ -83,6 +85,7 @@ def _find_issues(self, imported_modules: List[Module], dependencies: List[Depend
             result["misplaced_dev"] = MisplacedDevDependenciesFinder(
                 imported_modules=imported_modules,
                 dependencies=dependencies,
+                dev_dependencies=dev_dependencies,
                 ignore_misplaced_dev=self.ignore_misplaced_dev,
             ).find()
         return result

deptry/issue_finders/misplaced_dev.py

@@ -14,28 +14,58 @@ class MisplacedDevDependenciesFinder:
     """
 
     def __init__(
-        self, imported_modules: List[Module], dependencies: List[Dependency], ignore_misplaced_dev: List[str] = []
+        self,
+        imported_modules: List[Module],
+        dependencies: List[Dependency],
+        dev_dependencies: List[Dependency],
+        ignore_misplaced_dev: List[str] = [],
     ) -> None:
         self.imported_modules = imported_modules
         self.dependencies = dependencies
+        self.dev_dependencies = dev_dependencies
         self.ignore_misplaced_dev = ignore_misplaced_dev
 
     def find(self) -> List[str]:
+        """
+        In this function, we use 'corresponding_package_name' instead of module.package, since it can happen that a
+        development dependency is not installed, but it's still found to be used in the codebase, due to simple name matching.
+        In that case, it's added under module.dev_top_levels. _get_package_name is added for these edge-cases.
+        """
         logging.debug("\nScanning for incorrect development dependencies...")
-        dev_dependencies = []
+        misplaced_dev_dependencies = []
         for module in self.imported_modules:
             logging.debug(f"Scanning module {module.name}...")
-            if self._is_development_dependency(module):
-                dev_dependencies.append(module.package)
-        return dev_dependencies
+            corresponding_package_name = self._get_package_name(module)
+            if corresponding_package_name:
+                if self._is_development_dependency(module, corresponding_package_name):
+                    misplaced_dev_dependencies.append(corresponding_package_name)
+        return misplaced_dev_dependencies
 
-    def _is_development_dependency(self, module: Module) -> bool:
+    def _is_development_dependency(self, module: Module, corresponding_package_name: str) -> bool:
         if module.is_dev_dependency:
             if module.name in self.ignore_misplaced_dev:
                 logging.debug(
-                    f"Module '{module.package}' found to be a misplaced development dependency, but ignoring."
+                    f"Module '{corresponding_package_name}' found to be a misplaced development dependency, but ignoring."
                 )
             else:
-                logging.debug(f"Dependency '{module.package}' marked as a misplaced development dependency.")
+                logging.debug(
+                    f"Dependency '{corresponding_package_name}' marked as a misplaced development dependency."
+                )
                 return True
         return False
+
+    def _get_package_name(self, module: Module):
+        if module.package:
+            return module.package
+        if module.dev_top_levels:
+            if len(module.dev_top_levels) > 1:
+                logging.debug(
+                    f"Module {module.name} is found in the top-level module names of multiple development dependencies. Skipping."
+                )
+            elif len(module.dev_top_levels) == 0:
+                logging.debug(
+                    f"Module {module.name} has no metadata and it is not found in any top-level module names. Skipping."
+                )
+            else:
+                return module.dev_top_levels[0]
+        return None

tests/test_missing_dependencies_finder.py

@@ -18,3 +18,15 @@ def test_simple_with_ignore():
         imported_modules=modules, dependencies=dependencies, ignore_missing=["foobar"]
     ).find()
     assert len(deps) == 0
+
+
+def test_no_error():
+    """
+    This should run without an error, even though `foo` is not installed.
+    """
+
+    dep = Dependency("foo")
+    module = ModuleBuilder("foo", [dep]).build()
+
+    deps = MissingDependenciesFinder(imported_modules=[module], dependencies=[dep]).find()
+    assert len(deps) == 0