Merge pull request #59 from seddonym/remove-module

Add remove_module method

CHANGELOG.rst

@@ -57,3 +57,7 @@ Changelog
 1.0b10 (2019-5-15)
 ------------------
 * Fix Windows incompatibility.
+
+latest
+------
+* Add remove_module method.

docs/usage.rst

@@ -202,6 +202,15 @@ Methods for manipulating the graph
     :param bool is_squashed: If True, the module should be treated as a 'squashed module' (see `Terminology`_ above).
     :return: None
 
+.. py:function:: ImportGraph.remove_module(module)
+
+    Remove a module from the graph.
+
+    If the module is not present in the graph, no exception will be raised.
+
+    :param str module: The name of a module, for example ``'mypackage.foo'``.
+    :return: None
+
 .. py:function:: ImportGraph.add_import(importer, imported, line_number=None, line_contents=None)
 
     Add a direct import between two modules to the graph. If the modules are not already

src/grimp/adaptors/graph.py

@@ -41,6 +41,10 @@ def add_module(self, module: str, is_squashed: bool = False) -> None:
         if is_squashed:
             self._mark_module_as_squashed(module)
 
+    def remove_module(self, module: str) -> None:
+        if module in self.modules:
+            self._networkx_graph.remove_node(module)
+
     def add_import(
         self, *,
         importer: str,

src/grimp/application/ports/graph.py

@@ -30,6 +30,15 @@ def add_module(self, module: str, is_squashed: bool = False) -> None:
         """
         raise NotImplementedError
 
+    @abc.abstractmethod
+    def remove_module(self, module: str) -> None:
+        """
+        Remove a module from the graph, if it exists.
+
+        If the module is not present in the graph, no exception will be raised.
+        """
+        raise NotImplementedError
+
     @abc.abstractmethod
     def add_import(
         self, *,

tests/functional/test_build_and_use_graph.py

@@ -50,6 +50,15 @@ def test_add_module():
     assert number_of_modules + 1 == len(graph.modules)
 
 
+def test_remove_module():
+    graph = build_graph('testpackage')
+    number_of_modules = len(graph.modules)
+
+    graph.remove_module('testpackage.two.alpha')
+    assert 'testpackage.two.alpha' not in graph.modules
+    assert number_of_modules - 1 == len(graph.modules)
+
+
 def test_add_and_remove_import():
     graph = build_graph('testpackage')
     a = 'testpackage.one.delta.blue'

tests/unit/adaptors/test_graph.py

@@ -522,6 +522,21 @@ def test_add_module():
     assert graph.modules == {module}
 
 
+def test_remove_module():
+    graph = ImportGraph()
+    a, b = {'mypackage.blue', 'mypackage.green'}
+
+    graph.add_module(a)
+    graph.add_module(b)
+    graph.add_import(importer=a, imported=b)
+
+    graph.remove_module(b)
+    assert {a} == graph.modules
+
+    # Removing a non-existent module doesn't cause an error.
+    graph.remove_module('mypackage.yellow')
+
+
 class TestAddSquashedModule:
     def test_can_repeatedly_add_same_squashed_module(self):
         graph = ImportGraph()