Add tighter assertion per review, fix formatting

---
Signed-off-by: Michael Ferguson <[email protected]>

tools/chpl-language-server/test/diagnostics.py

@@ -53,17 +53,17 @@ async def test_incorrect_cross_file_diagnostics(client: LanguageClient):
     async with source_files(client, A=fileA, B=fileB) as docs:
         await save_file(client, docs("B"), docs("A"))
         assert len(client.diagnostics[docs("A").uri]) == 0
-        assert len(client.diagnostics[docs("B").uri]) >= 1
+        assert len(client.diagnostics[docs("B").uri]) == 2
 
         # check if the expected warnings are present
         foundImplicitModule = False
         foundSameName = False
         for d in client.diagnostics[docs("B").uri]:
-            if 'ImplicitFileModule' in d.message:
+            if "ImplicitFileModule" in d.message:
                 # Warning: [ImplicitFileModule]: an implicit module named 'B'
                 # is being introduced to contain file-scope code
                 foundImplicitModule = True
-            if 'ImplicitModuleSameName' in d.message:
+            if "ImplicitModuleSameName" in d.message:
                 # Warning: [ImplicitModuleSameName]: module 'B' has
                 # the same name as the implicit file module
                 foundSameName = True