Fix #1082 by ignoring proxy parameter if env parameter is set but empty (#1083)

Author: y-adachi-00one

slack_sdk/proxy_env_variable_loader.py

@@ -13,8 +13,14 @@ def load_http_proxy_from_env(logger: logging.Logger = _default_logger) -> Option
         or os.environ.get("HTTP_PROXY")
         or os.environ.get("http_proxy")
     )
-    if proxy_url is not None:
+    if proxy_url is None:
+        return None
+    if len(proxy_url.strip()) == 0:
+        # If the value is an empty string, the intention should be unsetting it
         logger.debug(
-            f"HTTP proxy URL has been loaded from an env variable: {proxy_url}"
+            "The Slack SDK ignored the proxy env variable as an empty value is set."
         )
+        return None
+
+    logger.debug(f"HTTP proxy URL has been loaded from an env variable: {proxy_url}")
     return proxy_url

tests/test_proxy_env_variable_loader.py

@@ -22,3 +22,19 @@ def test_load_upper_case(self):
         os.environ["HTTPS_PROXY"] = "http://localhost:9999"
         url = load_http_proxy_from_env()
         self.assertEqual(url, "http://localhost:9999")
+
+    def test_load_all_empty_case(self):
+        os.environ["HTTP_PROXY"] = ""
+        os.environ["http_proxy"] = ""
+        os.environ["HTTPS_PROXY"] = ""
+        os.environ["https_proxy"] = ""
+        url = load_http_proxy_from_env()
+        self.assertEqual(url, None)
+
+    def test_proxy_url_is_none_case(self):
+        os.environ.pop("HTTPS_PROXY", None)
+        os.environ.pop("https_proxy", None)
+        os.environ.pop("HTTP_PROXY", None)
+        os.environ.pop("http_proxy", None)
+        url = load_http_proxy_from_env()
+        self.assertEqual(url, None)