add more informative exception and regression test

Author: keflavich

astroquery/vizier/core.py

@@ -169,6 +169,9 @@ def find_catalogs(self, keywords, include_obsolete=False, verbose=False,
                                  url=self._server_to_url(),
                                  data=data_payload,
                                  timeout=self.TIMEOUT)
+        if 'STOP, Max. number of RESOURCE reached' in response.content:
+            raise ValueError("Maximum number of catalogs exceeded.  Try setting max_catalogs "
+                             "to a large number and try again")
         result = self._parse_result(response, verbose=verbose, get_catalog_names=True)
 
         # Filter out the obsolete catalogs, unless requested

astroquery/vizier/tests/test_vizier_remote.py

@@ -79,3 +79,15 @@ def test_multicoord(self):
         assert len(result) >= 5
         assert 'I/239/hip_main' in result.keys()
         assert result['I/239/hip_main']['HIP'] == 98298
+
+    def test_findcatalog_maxcatalog(self):
+        V = Vizier()
+        cats = Vizier.find_catalogs('eclipsing binary', max_catalogs=5000)
+        assert len(cats) >= 468
+
+        with pytest.raises(ValueError) as exc:
+            Vizier.find_catalogs('eclipsing binary')
+        assert str(exc.value)==("Maximum number of catalogs exceeded."
+                                "  Try setting max_catalogs "
+                                "to a large number and try again")
+