Use a cross-compat trick to squash chaining, stolen from pyparsing.py…

… (thanks PaulMcG)

.travis.yml

@@ -6,29 +6,21 @@ python:
   - "2.7"
   - "3.5"
   - "3.6"
+  - "3.7-dev"
   - "pypy"
-  - "pypy3.5"
+  - "pypy3"
   - "nightly"
 
 matrix:
   fast_finish: true
   allow_failures:
   - python: "nightly"
-  include:
-    - python: 3.7
-      dist: xenial
-      sudo: true
-
-before_install:
-  - sudo apt-get -y install python3-pip python3-setuptools
-  - sudo pip3 install flit
 
 install:
-  - pip install --upgrade pytest flit6
-  - flit install
+  - pip install "pytest>=3.3"
 
 script:
-  - pytest
+  - python -m pytest
 
 notifications:
   email: false

CHANGES.rst

@@ -1,3 +1,9 @@
+pytest-raisin 0.3 (2019-04-03)
+==============================
+
+- Improved cross-compat code, simplifying into a single .py module distribution.
+
+
 pytest-raisin 0.2 (2019-02-11)
 ==============================
 

pytest_raisin/__init__.py → pytest_raisin.py

@@ -4,10 +4,8 @@
 
 import pytest
 
-from pytest_raisin.compat import default_compare
 
-
-__version__ = "0.2"
+__version__ = "0.3"
 
 
 log = logging.getLogger(__name__)
@@ -68,6 +66,22 @@ def raises(expected_exception, *args, **kwargs):
     return original(expected_exception, *args, **kwargs)
 
 
+def default_compare(exc_actual, exc_expected):
+    __tracebackhide__ = True
+    actual_args = getattr(exc_actual, "args", None)
+    expected_args = getattr(exc_expected, "args", None)
+    if actual_args == expected_args:
+        return
+    msg = "{} args do not match!\n    Actual:   {}\n    Expected: {}"
+    msg = msg.format(type(exc_expected).__name__, actual_args, expected_args)
+    err = AssertionError(msg)
+    err.__cause__ = None
+    # as a side-effect, this also sets __suppress_context__
+    # that's a cross-compatible way of disabling chaining i.e. squashing the message
+    # "During handling of the above exception, another exception occurred"
+    raise err
+
+
 class RaisesContext(type(pytest.raises(Exception))):
 
     def __exit__(self, *tp):

tests/conftest.py

@@ -0,0 +1 @@
+pytest_plugins = ("pytester", "pytest_raisin")

tests/test_no_chaining.py

@@ -0,0 +1,17 @@
+def test_spurious_chaining_is_suppressed(testdir):
+    testdir.makepyfile("""
+        import pytest
+
+        def test_the_thing():
+            with pytest.raises(Exception("boom")):
+                raise Exception("bang")
+    """)
+    result = testdir.runpytest()
+    result.assert_outcomes(failed=1)
+    result.stdout.fnmatch_lines([
+        "E * AssertionError: Exception args do not match!",
+        "E *   Actual:   ('bang',)",
+        "E *   Expected: ('boom',)",
+    ])
+    text = result.stdout.str()
+    assert "During handling of the above exception, another exception occurred" not in text

tests/test_plugin.py

@@ -1,6 +1,3 @@
-pytest_plugins = ["pytester"]
-
-
 def test_using_exception_class(testdir):
     testdir.makepyfile("""
         import pytest

tests/test_register.py

@@ -1,6 +1,3 @@
-pytest_plugins = ["pytester", "pytest-raisin"]
-
-
 def test_user_registered_error_hook_pass(testdir):
     testdir.makepyfile("""
         import pytest