Add a new doctest_namespace fixture

This fixture can be used to inject names into the namespace in which
your doctests run.

AUTHORS

@@ -59,6 +59,7 @@ Marc Schlaich
 Mark Abramowitz
 Markus Unterwaditzer
 Martijn Faassen
+Matt Williams
 Michael Aquilina
 Michael Birtwell
 Michael Droettboom

CHANGELOG.rst

@@ -3,7 +3,8 @@
 
 **New Features**
 
-*
+* New ``doctest_namespace`` fixture for injecting names into the
+  namespace in which your doctests run.
 
 * 
 

_pytest/doctest.py

@@ -71,6 +71,8 @@ class DoctestItem(pytest.Item):
         if self.dtest is not None:
             self.fixture_request = _setup_fixtures(self)
             globs = dict(getfixture=self.fixture_request.getfuncargvalue)
+            for name, value in self.fixture_request.getfuncargvalue('doctest_namespace').items():
+                globs[name] = value
             self.dtest.globs.update(globs)
 
     def runtest(self):
@@ -159,6 +161,9 @@ class DoctestTextfile(DoctestItem, pytest.Module):
         if '__name__' not in globs:
             globs['__name__'] = '__main__'
 
+        for name, value in fixture_request.getfuncargvalue('doctest_namespace').items():
+            globs[name] = value
+
         optionflags = get_optionflags(self)
         runner = doctest.DebugRunner(verbose=0, optionflags=optionflags,
                                      checker=_get_checker())
@@ -288,3 +293,11 @@ def _get_allow_bytes_flag():
     """
     import doctest
     return doctest.register_optionflag('ALLOW_BYTES')
+
+
+@pytest.fixture(scope='session')
+def doctest_namespace():
+    """
+    Inject names into the doctest namespace.
+    """
+    return dict()

doc/en/doctest.rst

@@ -102,4 +102,29 @@ itself::
     >>> get_unicode_greeting()  # doctest: +ALLOW_UNICODE
     'Hello'
 
+The 'doctest_namespace' fixture
+-------------------------------
 
+The ``doctest_namespace`` fixture can be used to inject items into the
+namespace in which your doctests run. It is intended to be used within
+your own fixtures to provide the tests that use them with context.
+
+``doctest_namespace`` is a standard ``dict`` object into which you
+place the objects you want to appear in the doctest namespace::
+
+    # content of conftest.py
+    import numpy
+    @pytest.fixture(autouse=True)
+        def add_np(doctest_namespace):
+            doctest_namespace['np'] = numpy
+
+which can then be used in your doctests directly::
+
+    # content of numpy.py
+    def arange():
+        """
+        >>> a = np.arange(10)
+        >>> len(a)
+        10
+        """
+        pass

testing/test_doctest.py

@@ -713,3 +713,53 @@ class TestDoctestAutoUseFixtures:
         result = testdir.runpytest('--doctest-modules')
         assert 'FAILURES' not in str(result.stdout.str())
         result.stdout.fnmatch_lines(['*=== 1 passed in *'])
+
+
+class TestDoctestNamespaceFixture:
+
+    SCOPES = ['module', 'session', 'class', 'function']
+
+    @pytest.mark.parametrize('scope', SCOPES)
+    def test_namespace_doctestfile(self, testdir, scope):
+        """
+        Check that inserting something into the namespace works in a
+        simple text file doctest
+        """
+        testdir.makeconftest("""
+            import pytest
+            import contextlib
+
+            @pytest.fixture(autouse=True, scope="{scope}")
+            def add_contextlib(doctest_namespace):
+                doctest_namespace['cl'] = contextlib
+        """.format(scope=scope))
+        p = testdir.maketxtfile("""
+            >>> print(cl.__name__)
+            contextlib
+        """)
+        reprec = testdir.inline_run(p)
+        reprec.assertoutcome(passed=1)
+
+    @pytest.mark.parametrize('scope', SCOPES)
+    def test_namespace_pyfile(self, testdir, scope):
+        """
+        Check that inserting something into the namespace works in a
+        simple Python file docstring doctest
+        """
+        testdir.makeconftest("""
+            import pytest
+            import contextlib
+
+            @pytest.fixture(autouse=True, scope="{scope}")
+            def add_contextlib(doctest_namespace):
+                doctest_namespace['cl'] = contextlib
+        """.format(scope=scope))
+        p = testdir.makepyfile("""
+            def foo():
+                '''
+                >>> print(cl.__name__)
+                contextlib
+                '''
+        """)
+        reprec = testdir.inline_run(p, "--doctest-modules")
+        reprec.assertoutcome(passed=1)