Improve warning testing for bad patterns (#3)

disable_logging() manipulates a global setting so it may interfere with
any other concurrent tests.  Instead, use the @test_logs macro to
capture logs.

I've also chosen to specifically test that a warning is produced here
(rather than just use @test_logs min_level=Error which would be more
like without_warnings()).

test/runtests.jl

@@ -45,33 +45,26 @@ end
                 "~", "* *", "*~*", "***", "∀", "~, ***",
                 ".com", "*com", ".*com", ".example.com", "*example.com",
             ]
-            for pattern in patterns
-                ENV["JULIA_NO_VERIFY_HOSTS"] = pattern
-                for url in TEST_URLS, transport in TRANSPORTS
-                    verify = without_warnings() do
-                        verify_host(url, transport)
-                    end
-                    @test verify
+            for url in TEST_URLS, transport in TRANSPORTS
+                for pattern in patterns
+                    # NB: Setting ENV here in the inner loop so that we defeat
+                    # the ENV_HOST_PATTERN_CACHE and get a warning every time.
+                    ENV["JULIA_NO_VERIFY_HOSTS"] = pattern
+                    @test @test_logs (:warn, r"bad host pattern in ENV") match_mode=:any verify_host(url, transport)
                 end
             end
             clear_vars!(ENV)
         end
 
         @testset "only ignore bad patterns in list" begin
             patterns = ["ok.com,~", "^, ok.com ,, !"]
-            for pattern in patterns
-                ENV["JULIA_NO_VERIFY_HOSTS"] = pattern
-                for url in TEST_URLS
-                    verify = without_warnings() do
-                        verify_host(url)
-                    end
-                    @test verify
-                end
-                verify = without_warnings() do
-                    verify_host("ok.com")
+            for url in TEST_URLS
+                for pattern in patterns
+                    ENV["JULIA_NO_VERIFY_HOSTS"] = pattern
+                    @test @test_logs (:warn, r"bad host pattern in ENV") match_mode=:any verify_host(url)
                 end
-                @test !verify
-        end
+                @test @test_logs min_level=Logging.Error !verify_host("ok.com")
+            end
             clear_vars!(ENV)
         end
 

test/setup.jl

@@ -52,11 +52,3 @@ function clear_vars!(ENV)
     delete!(ENV, "JULIA_SSH_NO_VERIFY_HOSTS")
 end
 
-function without_warnings(body::Function)
-    log_level = Logging.min_enabled_level(current_logger())
-    disable_logging(Logging.Warn)
-    try body()
-    finally
-        disable_logging(log_level-1)
-    end
-end