ENH: make OutputChecker pluggable

scpdt/impl.py

@@ -85,6 +85,7 @@ class DTConfig:
         a string. If not empty, the string value is used as the skip reason.
     """
     def __init__(self, *, # DTChecker configuration
+                          CheckerKlass=None,
                           default_namespace=None,
                           check_namespace=None,
                           rndm_markers=None,
@@ -108,6 +109,8 @@ def __init__(self, *, # DTChecker configuration
                           pytest_extra_xfail=None,
     ):
         ### DTChecker configuration ###
+        self.CheckerKlass = CheckerKlass or DTChecker
+
         # The namespace to run examples in
         self.default_namespace = default_namespace or {}
 
@@ -340,7 +343,7 @@ def __init__(self, checker=None, verbose=None, optionflags=None, config=None):
         if config is None:
             config = DTConfig()
         if checker is None:
-            checker = DTChecker(config)
+            checker = config.CheckerKlass(config)
         self.nameerror_after_exception = config.nameerror_after_exception
         if optionflags is None:
             optionflags = config.optionflags

scpdt/plugin.py

@@ -213,7 +213,6 @@ def collect(self):
         runner = _get_runner(self.config,
             verbose=False,
             optionflags=optionflags,
-            checker=DTChecker(config=self.config.dt_config)
         )
 
         # strategy='api': discover doctests in public, non-deprecated objects in module
@@ -228,7 +227,7 @@ def collect(self):
                 yield pydoctest.DoctestItem.from_parent(
                     self, name=test.name, runner=runner, dtest=test
                 )
-        
+
 
 class DTTextfile(DoctestTextfile):
     """
@@ -253,7 +252,6 @@ def collect(self):
         runner = _get_runner(self.config,
             verbose=False,
             optionflags=optionflags,
-            checker=DTChecker(config=self.config.dt_config)
         )
 
         # Plug in an instance of `DTParser` which parses the doctest examples from the text file and
@@ -268,7 +266,7 @@ def collect(self):
             )
 
 
-def _get_runner(config, checker, verbose, optionflags):
+def _get_runner(config, verbose, optionflags):
     """
     Override function to return an instance of PytestDTRunner.
 
@@ -321,5 +319,5 @@ def report_unexpected_exception(self, out, test, example, exc_info):
                 out.append(failure)
             else:
                 raise failure
-            
-    return PytestDTRunner(checker=checker, verbose=verbose, optionflags=optionflags, config=config.dt_config)
+
+    return PytestDTRunner(verbose=verbose, optionflags=optionflags, config=config.dt_config)

scpdt/tests/test_pytest_configuration.py

@@ -42,3 +42,38 @@ def test_local_file_cases(pytester):
     python_file = PosixPath(path_str)
     result = pytester.inline_run(python_file, "--doctest-modules")
     assert result.ret == pytest.ExitCode.OK
+
+
+def test_alt_checker(pytester):
+    """Test an alternative Checker."""
+
+    # create a temporary conftest.py file
+    pytester.makeconftest(
+        """
+        import doctest
+        from scpdt.conftest import dt_config
+
+        class Vanilla(doctest.OutputChecker):
+            def __init__(self, config):
+                pass
+
+        dt_config.CheckerKlass = Vanilla
+    """
+    )
+
+    # create a temporary pytest test file
+    f = pytester.makepyfile(
+        """
+        def func():
+            '''
+            >>> 2 / 3     # fails with vanilla doctest.OutputChecker
+            0.667
+            '''
+            pass
+    """
+    )
+
+    # run all tests with pytest
+    result = pytester.inline_run(f, '--doctest-modules')
+    assert result.ret == pytest.ExitCode.TESTS_FAILED
+

scpdt/tests/test_runner.py

@@ -4,8 +4,10 @@
 
 import pytest
 
-from . import failure_cases as module, finder_cases as finder_module
-from .. import DTFinder, DTRunner, DebugDTRunner
+from . import (failure_cases as module,
+               finder_cases as finder_module,
+               module_cases)
+from .. import DTFinder, DTRunner, DebugDTRunner, DTConfig
 
 
 ### Smoke test DTRunner methods. Mainly to check that they are runnable.
@@ -79,3 +81,25 @@ def test_debug_runner_exception(self):
         # exception carries the original test
         assert orig_exception.test is tests[0]
 
+
+class VanillaOutputChecker(doctest.OutputChecker):
+    """doctest.OutputChecker to drop in for DTChecker.
+
+    LSP break: OutputChecker does not have __init__,
+    here we add it to agree with DTChecker.
+    """
+    def __init__(self, config):
+        pass
+
+class TestCheckerDropIn:
+    """Test DTChecker and vanilla doctest OutputChecker being drop-in replacements.
+    """
+    def test_vanilla_checker(self):
+        config = DTConfig(CheckerKlass=VanillaOutputChecker)
+        runner = DebugDTRunner(config=config)
+        tests = DTFinder().find(module_cases.func)
+
+        with pytest.raises(doctest.DocTestFailure) as exc:
+            for t in tests:
+                runner.run(t)
+