Allow parameterised fixtures to give paramemter IDs

This is just like the markers etc already can do.

CHANGELOG

@@ -1,6 +1,9 @@
 Unreleased
 -----------------------------------
 
+- Allow parameterized fixtures to specify the ID of the parameters by
+  adding an ids argument to pytest.fixture() and pytest.yield_fixture().
+
 - fix issue404 by always using the binary xml escape in the junitxml plugin
 
 2.5.0

_pytest/python.py

@@ -35,11 +35,13 @@ def getimfunc(func):
 
 
 class FixtureFunctionMarker:
-    def __init__(self, scope, params, autouse=False, yieldctx=False):
+    def __init__(self, scope, params,
+                 autouse=False, yieldctx=False, ids=None):
         self.scope = scope
         self.params = params
         self.autouse = autouse
         self.yieldctx = yieldctx
+        self.ids = ids
 
     def __call__(self, function):
         if inspect.isclass(function):
@@ -49,7 +51,7 @@ def __call__(self, function):
         return function
 
 
-def fixture(scope="function", params=None, autouse=False):
+def fixture(scope="function", params=None, autouse=False, ids=None):
     """ (return a) decorator to mark a fixture factory function.
 
     This decorator can be used (with or or without parameters) to define
@@ -71,16 +73,20 @@ def fixture(scope="function", params=None, autouse=False):
                 can see it.  If False (the default) then an explicit
                 reference is needed to activate the fixture.
 
+    :arg ids: list of string ids each corresponding to the argvalues
+       so that they are part of the test id. If no ids are provided
+       they will be generated automatically from the argvalues.
+
     """
     if callable(scope) and params is None and autouse == False:
         # direct decoration
         return FixtureFunctionMarker(
                 "function", params, autouse)(scope)
     if params is not None and not isinstance(params, (list, tuple)):
         params = list(params)
-    return FixtureFunctionMarker(scope, params, autouse)
+    return FixtureFunctionMarker(scope, params, autouse, ids=ids)
 
-def yield_fixture(scope="function", params=None, autouse=False):
+def yield_fixture(scope="function", params=None, autouse=False, ids=None):
     """ (return a) decorator to mark a yield-fixture factory function
     (EXPERIMENTAL).
 
@@ -94,7 +100,8 @@ def yield_fixture(scope="function", params=None, autouse=False):
         return FixtureFunctionMarker(
                 "function", params, autouse, yieldctx=True)(scope)
     else:
-        return FixtureFunctionMarker(scope, params, autouse, yieldctx=True)
+        return FixtureFunctionMarker(scope, params, autouse,
+                                     yieldctx=True, ids=ids)
 
 defaultfuncargprefixmarker = fixture()
 
@@ -1623,7 +1630,8 @@ def pytest_generate_tests(self, metafunc):
             for fixturedef in faclist:
                 if fixturedef.params is not None:
                     metafunc.parametrize(argname, fixturedef.params,
-                                         indirect=True, scope=fixturedef.scope)
+                                         indirect=True, scope=fixturedef.scope,
+                                         ids=fixturedef.ids)
 
     def pytest_collection_modifyitems(self, items):
         # separate parametrized setups
@@ -1660,7 +1668,7 @@ def parsefactories(self, node_or_obj, nodeid=NOTSET, unittest=False):
             fixturedef = FixtureDef(self, nodeid, name, obj,
                                     marker.scope, marker.params,
                                     yieldctx=marker.yieldctx,
-                                    unittest=unittest)
+                                    unittest=unittest, ids=marker.ids)
             faclist = self._arg2fixturedefs.setdefault(name, [])
             if fixturedef.has_location:
                 faclist.append(fixturedef)
@@ -1728,7 +1736,7 @@ def teardown():
 class FixtureDef:
     """ A container for a factory definition. """
     def __init__(self, fixturemanager, baseid, argname, func, scope, params,
-        yieldctx, unittest=False):
+                 yieldctx, unittest=False, ids=None):
         self._fixturemanager = fixturemanager
         self.baseid = baseid or ''
         self.has_location = baseid is not None
@@ -1741,6 +1749,7 @@ def __init__(self, fixturemanager, baseid, argname, func, scope, params,
         self.argnames = getfuncargnames(func, startindex=startindex)
         self.yieldctx = yieldctx
         self.unittest = unittest
+        self.ids = ids
         self._finalizer = []
 
     def addfinalizer(self, finalizer):

testing/python/fixture.py

@@ -1989,6 +1989,40 @@ def test_something(test_app):
         reprec = testdir.inline_run()
         reprec.assertoutcome(passed=1)
 
+    def test_params_and_ids(self, testdir):
+        testdir.makepyfile("""
+            import pytest
+
+            @pytest.fixture(params=[object(), object()],
+                            ids=['alpha', 'beta'])
+            def fix(request):
+                return request.param
+
+            def test_foo(fix):
+                assert 1
+        """)
+        res = testdir.runpytest('-v')
+        res.stdout.fnmatch_lines([
+            '*test_foo*alpha*',
+            '*test_foo*beta*'])
+
+    def test_params_and_ids_yieldfixture(self, testdir):
+        testdir.makepyfile("""
+            import pytest
+
+            @pytest.yield_fixture(params=[object(), object()],
+                                  ids=['alpha', 'beta'])
+            def fix(request):
+                 yield request.param
+
+            def test_foo(fix):
+                assert 1
+        """)
+        res = testdir.runpytest('-v')
+        res.stdout.fnmatch_lines([
+            '*test_foo*alpha*',
+            '*test_foo*beta*'])
+
 
 class TestRequestScopeAccess:
     pytestmark = pytest.mark.parametrize(("scope", "ok", "error"),[