Added tests for check_toml

Also assures we print filename when error occurs.
diff --git a/tests/check_toml_test.py b/tests/check_toml_test.py
new file mode 100644
index 0000000..1172c40
--- /dev/null
+++ b/tests/check_toml_test.py
@@ -0,0 +1,32 @@
+from __future__ import absolute_import
+from __future__ import unicode_literals
+
+from pre_commit_hooks.check_toml import main
+
+
+def test_toml_good(tmpdir):
+    filename = tmpdir.join('f')
+    filename.write("""
+key = # INVALID
+
+= "no key name"  # INVALID
+""")
+    ret = main((filename.strpath,))
+    assert ret == 1
+
+
+def test_toml_bad(tmpdir):
+    filename = tmpdir.join('f')
+    filename.write(
+        """
+# This is a TOML document.
+
+title = "TOML Example"
+
+[owner]
+name = "John"
+dob = 1979-05-27T07:32:00-08:00 # First class dates
+""",
+    )
+    ret = main((filename.strpath,))
+    assert ret == 0