tests: Fix test coverage on recent commit.

I guess `test_classes` has 100% line coverage
enforcement, which is a bit tricky for error
handling.

This fixes that, as well as making the name
snake_case and improving the format of the
errors.

zerver/lib/test_classes.py

@@ -821,7 +821,7 @@ class ZulipTestCase(TestCase):
             r for r in data
             if r['id'] == db_id][0]
 
-    def findOne(self,
+    def find_one(self,
                  lst: List[Any],
                  predicate: Callable[[Any], bool],
                  member_name: str) -> Any:
@@ -834,10 +834,14 @@ class ZulipTestCase(TestCase):
             # Happy path!
             return matches[0]
 
+        if True:  # nocoverage
             print('\nERROR: findOne fails on this list:\n')
+            print('[')
 
             for item in lst:
-            print(item)
+                print('   ', item, ',')
+
+            print(']')
 
             if len(matches) == 0:
                 raise ValueError(

zerver/tests/test_users.py

@@ -1387,7 +1387,7 @@ class GetProfileTest(ZulipTestCase):
         result = self.api_get(hamlet, "/api/v1/users")
         self.assert_json_success(result)
 
-        my_user = self.findOne(
+        my_user = self.find_one(
             result.json()['members'],
             lambda user: user['email'] == hamlet.email,
             'member for Hamlet'