Fail on unrecognized configuration options. #386

3 files changed, 54 insertions, 1 deletions

diff --git a/CHANGES.txt b/CHANGES.txt
index ffa4f32e..1211e8e3 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -20,6 +20,10 @@ Latest
   stored in the `runs` section of the data file.  You can use this to annotate
   the data file with any information you like.
 
+- Unrecognized configuration options will now print an error message and stop
+  coverage.py.  This should help prevent configuration mistakes from passing
+  silently.  Finishes `issue 386`_.
+
 - The XML report now includes a ``missing-branches`` attribute.  Thanks, Steve
   Peak.  This is not a part of the Cobertura DTD, so the XML report no longer
   references the DTD.
@@ -47,6 +51,7 @@ Latest
 .. _issue 275: https://bitbucket.org/ned/coveragepy/issues/275/refer-consistently-to-project-as-coverage
 .. _issue 313: https://bitbucket.org/ned/coveragepy/issues/313/add-license-file-containing-2-3-or-4
 .. _issue 380: https://bitbucket.org/ned/coveragepy/issues/380/code-executed-by-exec-excluded-from
+.. _issue 386: https://bitbucket.org/ned/coveragepy/issues/386/error-on-unrecognised-configuration
 
 .. 41 issues closed in 4.0 below here
 
diff --git a/coverage/config.py b/coverage/config.py
index edcf13e8..9939d6c0 100644
--- a/coverage/config.py
+++ b/coverage/config.py
@@ -3,7 +3,11 @@
 
 """Config file for coverage.py"""
 
-import os, re, sys
+import collections
+import os
+import re
+import sys
+
 from coverage.backward import configparser, iitems, string_class
 from coverage.misc import CoverageException
 
@@ -221,6 +225,23 @@ class CoverageConfig(object):
         except ValueError as err:
             raise CoverageException("Couldn't read config file %s: %s" % (filename, err))
 
+        # Check that there are no unrecognized options.
+        all_options = collections.defaultdict(set)
+        for option_spec in self.CONFIG_FILE_OPTIONS:
+            section, option = option_spec[1].split(":")
+            all_options[section].add(option)
+
+        for section, options in iitems(all_options):
+            if cp.has_section(section):
+                for unknown in set(cp.options(section)) - options:
+                    if section_prefix:
+                        section = section_prefix + section
+                    raise CoverageException(
+                        "Unrecognized option '[%s] %s=' in config file %s" % (
+                            section, unknown, filename
+                        )
+                    )
+
         # [paths] is special
         if cp.has_section('paths'):
             for option in cp.options('paths'):
diff --git a/tests/test_config.py b/tests/test_config.py
index 2b325073..6873e85d 100644
--- a/tests/test_config.py
+++ b/tests/test_config.py
@@ -182,6 +182,33 @@ class ConfigTest(CoverageTest):
         with self.assertRaises(CoverageException):
             _ = cov.config["no_such.plugin:foo"]
 
+    def test_unknown_option(self):
+        self.make_file(".coveragerc", """\
+            [run]
+            xyzzy = 17
+            """)
+        msg = r"Unrecognized option '\[run\] xyzzy=' in config file .coveragerc"
+        with self.assertRaisesRegex(CoverageException, msg):
+            _ = coverage.Coverage()
+
+    def test_misplaced_option(self):
+        self.make_file(".coveragerc", """\
+            [report]
+            branch = True
+            """)
+        msg = r"Unrecognized option '\[report\] branch=' in config file .coveragerc"
+        with self.assertRaisesRegex(CoverageException, msg):
+            _ = coverage.Coverage()
+
+    def test_unknown_option_in_other_ini_file(self):
+        self.make_file("setup.cfg", """\
+            [coverage:run]
+            huh = what?
+            """)
+        msg = r"Unrecognized option '\[coverage:run\] huh=' in config file setup.cfg"
+        with self.assertRaisesRegex(CoverageException, msg):
+            _ = coverage.Coverage()
+
 
 class ConfigFileTest(CoverageTest):
     """Tests of the config file settings in particular."""