Provide a more useful error message if failing to run a non-Python file. #514

4 files changed, 36 insertions, 6 deletions

diff --git a/CHANGES.rst b/CHANGES.rst
index 1c40c2e2..4c6ba6d8 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -55,6 +55,9 @@ Unreleased
 - Fixed an unusual bug involving multiple coding declarations affecting code
   containing code in multi-line strings: `issue 529`_.
 
+- If you try to run a non-Python file with coverage.py, you will now get a more
+  useful error message. `Issue 514`_.
+
 - The default pragma regex changed slightly, but this will only matter to you
   if you are deranged and use mixed-case pragmas.
 
@@ -80,6 +83,7 @@ Unreleased
 .. _issue 265: https://bitbucket.org/ned/coveragepy/issues/265/when-using-source-include-is-silently
 .. _issue 412: https://bitbucket.org/ned/coveragepy/issues/412/coverage-combine-should-error-if-no
 .. _issue 505: https://bitbucket.org/ned/coveragepy/issues/505/use-canonical-filename-for-debounce
+.. _issue 514: https://bitbucket.org/ned/coveragepy/issues/514/path-to-problem-file-not-reported-when
 .. _issue 510: https://bitbucket.org/ned/coveragepy/issues/510/erase-still-needed-in-42
 .. _issue 511: https://bitbucket.org/ned/coveragepy/issues/511/version-42-coverage-combine-empties
 .. _issue 516: https://bitbucket.org/ned/coveragepy/issues/516/running-coverage-combine-twice-deletes-all
diff --git a/CONTRIBUTORS.txt b/CONTRIBUTORS.txt
index 36db14bb..60d43ef3 100644
--- a/CONTRIBUTORS.txt
+++ b/CONTRIBUTORS.txt
@@ -17,6 +17,7 @@ Calen Pennington
 Carl Gieringer
 Catherine Proulx
 Chris Adams
+Chris Jerdonek
 Chris Rose
 Christian Heimes
 Christine Lytwynec
diff --git a/coverage/execfile.py b/coverage/execfile.py
index 3e20a527..58b05402 100644
--- a/coverage/execfile.py
+++ b/coverage/execfile.py
@@ -10,7 +10,7 @@ import types
 
 from coverage.backward import BUILTINS
 from coverage.backward import PYC_MAGIC_NUMBER, imp, importlib_util_find_spec
-from coverage.misc import ExceptionDuringRun, NoCode, NoSource, isolate_module
+from coverage.misc import CoverageException, ExceptionDuringRun, NoCode, NoSource, isolate_module
 from coverage.phystokens import compile_unicode
 from coverage.python import get_python_source
 
@@ -166,11 +166,17 @@ def run_python_file(filename, args, package=None, modulename=None, path0=None):
     sys.path[0] = path0 if path0 is not None else my_path0
 
     try:
-        # Make a code object somehow.
-        if filename.endswith((".pyc", ".pyo")):
-            code = make_code_from_pyc(filename)
-        else:
-            code = make_code_from_py(filename)
+        try:
+            # Make a code object somehow.
+            if filename.endswith((".pyc", ".pyo")):
+                code = make_code_from_pyc(filename)
+            else:
+                code = make_code_from_py(filename)
+        except CoverageException:
+            raise
+        except Exception as exc:
+            msg = "Couldn't run {filename!r} as Python code: {exc.__class__.__name__}: {exc}"
+            raise CoverageException(msg.format(filename=filename, exc=exc))
 
         # Execute the code object.
         try:
diff --git a/tests/test_execfile.py b/tests/test_execfile.py
index 889d6cfd..8585b16d 100644
--- a/tests/test_execfile.py
+++ b/tests/test_execfile.py
@@ -145,6 +145,25 @@ class RunPycFileTest(CoverageTest):
         with self.assertRaisesRegex(NoCode, "No file to run: 'xyzzy.pyc'"):
             run_python_file("xyzzy.pyc", [])
 
+    def test_running_py_from_binary(self):
+        # Use make_file to get the bookkeeping. Ideally, it would
+        # be able to write binary files.
+        bf = self.make_file("binary")
+        with open(bf, "wb") as f:
+            f.write(b'\x7fELF\x02\x01\x01\x00\x00\x00')
+
+        msg = (
+            r"Couldn't run 'binary' as Python code: "
+            r"(TypeError|ValueError): "
+            r"("
+            r"compile\(\) expected string without null bytes"    # for py2
+            r"|"
+            r"source code string cannot contain null bytes"     # for py3
+            r")"
+        )
+        with self.assertRaisesRegex(Exception, msg):
+            run_python_file(bf, [bf])
+
 
 class RunModuleTest(CoverageTest):
     """Test run_python_module."""