Add a few new negative dfilter tests.

For example, to ensure that "field = value" is not a valid dfilter (as was
recently a problem).

As suggested by Alexis.

Change-Id: Ibf498c30325579e3d5474bb2d397f1bbb9ffc07f
Reviewed-on: https://code.wireshark.org/review/11339
Reviewed-by: Anders Broman <a.broman58@gmail.com>

tools/dftestlib/integer.py

@@ -4,12 +4,12 @@
 # modify it under the terms of the GNU General Public License
 # as published by the Free Software Foundation; either version 2
 # of the License, or (at your option) any later version.
-# 
+#
 # This program is distributed in the hope that it will be useful,
 # but WITHOUT ANY WARRANTY; without even the implied warranty of
 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 # GNU General Public License for more details.
-# 
+#
 # You should have received a copy of the GNU General Public License
 # along with this program; if not, write to the Free Software
 # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
@@ -28,6 +28,21 @@ class testInteger(dftest.DFTest):
         dfilter = "ip.version == 6"
         self.assertDFilterCount(dfilter, 0)
 
+    def test_eq_3(self):
+	# Invalid filter (only one equals sign)
+        dfilter = "ip.version = 4"
+        self.assertDFilterFail(dfilter)
+
+    def test_eq_4(self):
+	# Invalid filter
+        dfilter = "ip.version == the quick brown fox jumps over the lazy dog"
+        self.assertDFilterFail(dfilter)
+
+    def test_eq_5(self):
+	# Invalid filter
+        dfilter = "ip.version == 4 the quick brown fox jumps over the lazy dog"
+        self.assertDFilterFail(dfilter)
+
     def test_ne_1(self):
         dfilter = "ip.version != 0"
         self.assertDFilterCount(dfilter, 1)