variants: Reject values with whitespace

If there is leading or trailing whitespace in a comps group name, it
will not be included in the compose and there will even be no error
message. Whitespace on module name results in a failure.

To avoid these errors, validating the variants file will now also check
that there is no whitespace in significant places, and abort the compose
if there a problem.

Signed-off-by: Lubomír Sedlář <lsedlar@redhat.com>

tests/test_variant_wrapper.py

@@ -0,0 +1,35 @@
+# -*- coding: utf-8 -*-
+
+try:
+    import unittest2 as unittest
+except ImportError:
+    import unittest
+import os
+import sys
+from six.moves import cStringIO
+
+sys.path.insert(0, os.path.join(os.path.dirname(__file__), ".."))
+
+from pungi.wrappers.variants import VariantsXmlParser
+
+VARIANTS_WITH_WHITESPACE = """
+<variants>
+  <variant id="Foo" name="Foo" type="variant">
+    <arches><arch>x86_64 </arch></arches>
+    <groups><group> core</group></groups>
+    <environments><environment> foo </environment></environments>
+  </variant>
+</variants>
+"""
+
+
+class TestVariantsXmlParser(unittest.TestCase):
+    def test_whitespace_in_file(self):
+        input = cStringIO(VARIANTS_WITH_WHITESPACE)
+
+        with self.assertRaises(ValueError) as ctx:
+            VariantsXmlParser(input)
+
+        self.assertIn("Tag arch on line 4", str(ctx.exception))
+        self.assertIn("Tag group on line 5", str(ctx.exception))
+        self.assertIn("Tag environment on line 6", str(ctx.exception))