fixed test runner script for AppVeyor

example/run_test.py

@@ -25,7 +25,8 @@ def sanitize(lines):
         line = line.strip()
         if sys.platform == 'win32':
             lower = line.lower()
-            if 'constructor' in lower or 'destructor' in lower or 'ref' in lower:
+            if 'constructor' in lower or 'destructor' in lower \
+               or 'ref' in lower:
                 line = ""
         lines[i] = line
 
@@ -40,7 +41,15 @@ def sanitize(lines):
     os.chdir(path)
 
 name = sys.argv[1]
-output_bytes = subprocess.check_output([sys.executable, name + ".py"])
+try:
+    output_bytes = subprocess.check_output([sys.executable, name + ".py"],
+                                           stderr=subprocess.STDOUT)
+except subprocess.CalledProcessError as e:
+    if 'import numpy' in e.output:
+        print('Test "%s" could not be run (NumPy is not installed).' % name)
+        exit(0)
+    raise
+
 output    = sanitize(output_bytes.decode('utf-8'))
 reference = sanitize(open(name + '.ref', 'r').read())