Adding pydot --fixture-graph

Author: Israel Fruchter (ifruchte)

README.rst

@@ -47,6 +47,49 @@ Output can look like this:
     tests/fixtures/order.py:30
     tests/unit/api/conftest.py:261
 
+You can also generate the usage fixture graph like that:
+
+.. sourcecode::
+    pytest --fixture-graph -s
+
+The Output would be like that:
+
+.. sourcecode::
+   ============================= test session starts =============================
+   platform win32 -- Python 2.7.10, pytest-3.3.1, py-1.5.2, pluggy-0.6.0
+   rootdir: C:\Users\ifruchte\Projects\pytest-fixture-tools, inifile: tox.ini
+   plugins: pep8-1.0.6, cov-2.5.1, fixture-tools-1.0.0
+   collected 7 items
+
+   pytest_fixture_tools\__init__.py .                                       [ 14%]
+   pytest_fixture_tools\plugin.py .                                         [ 28%]
+   tests\__init__.py .                                                      [ 42%]
+   tests\conftest.py .                                                      [ 57%]
+   tests\test_fixture_duplicates.py .
+   -------------------------------- fixture-graph --------------------------------
+   created at artifacts/fixture-graph-tests-test_fixture_duplicates.py__test_there_are_not_fixture_duplicates.dot.
+   You can convert it to a PNG using 'dot -Tpng artifacts/fixture-graph-tests-test_fixture_duplicates.py__test_there_are_not_fixture_duplicates.dot -o artifacts/fixture-graph-tests-test_fixture_duplicates.py__test_there_are_not_fixture_duplicates.png'
+   ============================= test session starts =============================
+   platform win32 -- Python 2.7.10, pytest-3.3.1, py-1.5.2, pluggy-0.6.0
+   rootdir: c:\users\ifruchte\appdata\local\temp\pytest-of-ifruchte\pytest-445\test_there_are_not_fixture_duplicates0, inifile:
+   plugins: pep8-1.0.6, cov-2.5.1, fixture-tools-1.0.0
+   collected 2 items
+
+   ======================== no tests ran in 0.06 seconds =========================
+   .s                                     [100%]
+
+   ===================== 6 passed, 1 skipped in 0.29 seconds =====================
+
+And running the hinted command:
+
+.. sourcecode::
+    dot -Tpng artifacts/fixture-graph-tests-test_fixture_duplicates.py__test_there_are_not_fixture_duplicates.dot -o artifacts/fixture-graph-tests-test_fixture_duplicates.py__test_there_are_not_fixture_duplicates.png
+
+would provide this output, that can help under a test that depend on large amount of fixtures:
+
+.. image:: imgs/graph_example.png
+    :alt: alternate text
+    :align: right
 
 Contact
 -------

pytest_fixture_tools/plugin.py

@@ -1,14 +1,28 @@
 """Pytest fixture tools plugin."""
 
 import py
+import os
+import errno
 
 from _pytest.python import getlocation
 from collections import defaultdict
 
+import pydot
+
 tw = py.io.TerminalWriter()
 verbose = 1
 
 
+def mkdir_recursive(path):
+    try:
+        os.makedirs(path)
+    except OSError as exc:
+        if exc.errno == errno.EEXIST and os.path.isdir(path):
+            pass
+        else:
+            raise
+
+
 def pytest_addoption(parser):
     """Add commandline options show-fixture-duplicates and fixture."""
     group = parser.getgroup("general")
@@ -18,6 +32,9 @@ def pytest_addoption(parser):
     group.addoption('--fixture',
                     action="store", type=str, dest="fixture_name", default='',
                     help="Name of specific fixture for which you want to get duplicates")
+    group.addoption('--fixture-graph',
+                    action="store_true", dest="fixture_graph", default=False,
+                    help="create .dot fixture graph for each test")
 
 
 def pytest_cmdline_main(config):
@@ -93,3 +110,39 @@ def _show_fixture_duplicates_main(config, session):
         for argname, fixtures in available:
             print_duplicates(argname, fixtures, previous_argname)
             previous_argname = argname
+
+
+def pytest_runtest_setup(item):
+    if item.config.option.fixture_graph and hasattr(item, "_fixtureinfo"):
+        curdir = py.path.local()
+        # fixtures came from function parameters names
+        data = dict()
+        data['func_args'] = item._fixtureinfo.argnames, 'red'
+        for fixture_name, fixture_data in list(item._fixtureinfo.name2fixturedefs.items()):
+
+            loc = getlocation(fixture_data[0].func, curdir)
+            if 'pytest_vgw' in loc:
+                color = 'yellow'
+            else:
+                color = 'green'
+            data[fixture_name] = fixture_data[0].argnames, color
+
+        graph = pydot.Dot(graph_type='digraph')
+
+        for name, depended_list in list(data.items()):
+            depended_list, color = depended_list
+
+            node = pydot.Node(name, style="filled", fillcolor=color)
+            graph.add_node(node)
+            for i in depended_list:
+                edge = pydot.Edge(node, i)
+                graph.add_edge(edge)
+
+        log_dir = os.environ.get('LOG_DEST_DIR', 'artifacts')
+        mkdir_recursive(log_dir)
+        filename = "{0}/fixture-graph-{1}".format(log_dir, item._nodeid.replace(":", "_").replace("/", "-"))
+        graph.write(filename + ".dot")
+        tw.line()
+        tw.sep("-", "fixture-graph")
+        tw.line("created at {}.dot.".format(filename))
+        tw.line("You can convert it to a PNG using 'dot -Tpng {0}.dot -o {0}.png'".format(filename))

setup.py

@@ -52,7 +52,7 @@ def run_tests(self):
     ] + [('Programming Language :: Python :: %s' % x) for x in '2.6 2.7 3.0 3.1 3.2 3.3'.split()],
     cmdclass={'test': ToxTestCommand},
     install_requires=[
-        'pytest',
+        'pytest', 'pydot'
     ],
     # the following makes a plugin available to py.test
     entry_points={