Merge pull request #473 from watsona4/path-search-fix

Path search fix

Cython/Coverage.py

@@ -8,6 +8,7 @@ from __future__ import absolute_import
 
 import re
 import os.path
+import sys
 from collections import defaultdict
 
 from coverage.plugin import CoveragePlugin, FileTracer, FileReporter  # requires coverage.py 4.0+
@@ -35,6 +36,12 @@ def _find_dep_file_path(main_file, file_path):
         pxi_file_path = os.path.join(os.path.dirname(main_file), file_path)
         if os.path.exists(pxi_file_path):
             abs_path = os.path.abspath(pxi_file_path)
+    # search sys.path for external locations if a valid file hasn't been found
+    if not os.path.exists(abs_path):
+        for sys_path in sys.path:
+            test_path = os.path.realpath(os.path.join(sys_path, file_path))
+            if os.path.exists(test_path):
+                return test_path
     return abs_path
 
 
@@ -132,7 +139,7 @@ class Plugin(CoveragePlugin):
             try:
                 with open(c_file, 'rb') as f:
                     if b'/* Generated by Cython ' not in f.read(30):
-                        return None  # not a Cython file
+                        return None, None  # not a Cython file
             except (IOError, OSError):
                 c_file = None
 
@@ -238,7 +245,7 @@ class CythonModuleTracer(FileTracer):
             return self._file_path_map[source_file]
         except KeyError:
             pass
-        abs_path = os.path.abspath(source_file)
+        abs_path = _find_dep_file_path(filename, source_file)
 
         if self.py_file and source_file[-3:].lower() == '.py':
             # always let coverage.py handle this case itself