Give error messages if an explicitly provided rcfile can't be read.

4 files changed, 53 insertions, 22 deletions

diff --git a/CHANGES.txt b/CHANGES.txt
index 7a9036b0..206fbf35 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -27,6 +27,9 @@ Latest
   column is a "partial branches" column so that both reports show the same
   numbers.  This closes `issue 342`_.
 
+- If you specify a ``--rcfile`` that cannot be read, you will get an error
+  message.  Fixes `issue 343`_.
+
 - The ``--debug`` switch can now be used on any command.
 
 - You can now programmatically adjust the configuration of coverage by setting
@@ -40,6 +43,7 @@ Latest
 
 .. _issue 328: https://bitbucket.org/ned/coveragepy/issue/328/misbehavior-in-run-source
 .. _issue 342: https://bitbucket.org/ned/coveragepy/issue/342/console-and-html-coverage-reports-differ
+.. _issue 343: https://bitbucket.org/ned/coveragepy/issue/343/an-explicitly-named-non-existent-config
 
 
 Version 4.0a1 --- 27 September 2014
diff --git a/coverage/config.py b/coverage/config.py
index 9598f74d..65f4222a 100644
--- a/coverage/config.py
+++ b/coverage/config.py
@@ -197,14 +197,24 @@ class CoverageConfig(object):
         self.attempted_config_files.append(filename)
 
         cp = HandyConfigParser(section_prefix)
-        files_read = cp.read(filename)
+        try:
+            files_read = cp.read(filename)
+        except configparser.Error as err:
+            raise CoverageException(
+                "Couldn't read config file %s: %s" % (filename, err)
+                )
         if not files_read:
             return False
 
         self.config_files.extend(files_read)
 
-        for option_spec in self.CONFIG_FILE_OPTIONS:
-            self._set_attr_from_config_option(cp, *option_spec)
+        try:
+            for option_spec in self.CONFIG_FILE_OPTIONS:
+                self._set_attr_from_config_option(cp, *option_spec)
+        except ValueError as err:
+            raise CoverageException(
+                "Couldn't read config file %s: %s" % (filename, err)
+                )
 
         # [paths] is special
         if cp.has_section('paths'):
diff --git a/coverage/control.py b/coverage/control.py
index 815c16b9..6aa06da8 100644
--- a/coverage/control.py
+++ b/coverage/control.py
@@ -94,20 +94,20 @@ class Coverage(object):
         # 1: defaults:
         self.config = CoverageConfig()
 
-        # 2: from the .coveragerc or setup.cfg file:
+        # 2: from the rcfile, .coveragerc or setup.cfg file:
         if config_file:
-            did_read_rc = should_read_setupcfg = False
-            if config_file is True:
+            did_read_rc = False
+            specified_file = (config_file is not True)
+            if not specified_file:
                 config_file = ".coveragerc"
-                should_read_setupcfg = True
-            try:
-                did_read_rc = self.config.from_file(config_file)
-            except ValueError as err:
-                raise CoverageException(
-                    "Couldn't read config file %s: %s" % (config_file, err)
-                    )
-
-            if not did_read_rc and should_read_setupcfg:
+
+            did_read_rc = self.config.from_file(config_file)
+
+            if not did_read_rc:
+                if specified_file:
+                    raise CoverageException(
+                        "Couldn't read %r as a config file" % config_file
+                        )
                 self.config.from_file("setup.cfg", section_prefix="coverage:")
 
         # 3: from environment variables:
diff --git a/tests/test_config.py b/tests/test_config.py
index 26a22222..34727ae6 100644
--- a/tests/test_config.py
+++ b/tests/test_config.py
@@ -91,13 +91,18 @@ class ConfigTest(CoverageTest):
         self.assertEqual(cov.config.data_file, "fromarg.dat")
 
     def test_parse_errors(self):
-        # Im-parseable values raise CoverageException
-        self.make_file(".coveragerc", """\
-            [run]
-            timid = maybe?
-            """)
-        with self.assertRaises(CoverageException):
-            coverage.coverage()
+        # Im-parseable values raise CoverageException, with details.
+        bad_configs_and_msgs = [
+            ("[run]\ntimid = maybe?\n", r"maybe[?]"),
+            ("timid = 1\n", r"timid = 1"),
+            ("[run\n", r"\[run"),
+            ]
+
+        for bad_config, msg in bad_configs_and_msgs:
+            print("Trying %r" % bad_config)
+            self.make_file(".coveragerc", bad_config)
+            with self.assertRaisesRegex(CoverageException, msg):
+                coverage.coverage()
 
     def test_environment_vars_in_config(self):
         # Config files can have $envvars in them.
@@ -339,3 +344,15 @@ class ConfigFileTest(CoverageTest):
         self.assertEqual(cov.config.html_title,
             "tabblo & «ταБЬℓσ» # numbers"
             )
+
+    def test_unreadable_config(self):
+        # If a config file is explicitly specified, then it is an error for it
+        # to not be readable.
+        bad_files = [
+            "nosuchfile.txt",
+            ".",
+            ]
+        for bad_file in bad_files:
+            msg = "Couldn't read %r as a config file" % bad_file
+            with self.assertRaisesRegex(CoverageException, msg):
+                coverage.coverage(config_file=bad_file)