Add test case for the empty proxy bypass list configured

Simplify other config test cases with using predicate assertions instead of
expectations.

test/test_config.cc

@@ -10,29 +10,30 @@
 TEST(config, override_auto_config_url) {
     proxy_config_set_auto_config_url_override("http://127.0.0.1:8000/wpad.dat");
     char *auto_config_url = proxy_config_get_auto_config_url();
-    EXPECT_NE(auto_config_url, nullptr);
-    if (auto_config_url) {
-        EXPECT_STREQ(auto_config_url, "http://127.0.0.1:8000/wpad.dat");
-        free(auto_config_url);
-    }
+    ASSERT_NE(auto_config_url, nullptr);
+    EXPECT_STREQ(auto_config_url, "http://127.0.0.1:8000/wpad.dat");
+    free(auto_config_url);
 }
 
 TEST(config, override_proxy) {
     proxy_config_set_proxy_override("http://127.0.0.1:8000/");
     char *proxy = proxy_config_get_proxy("http");
-    EXPECT_NE(proxy, nullptr);
-    if (proxy) {
-        EXPECT_STREQ(proxy, "http://127.0.0.1:8000/");
-        free(proxy);
-    }
+    ASSERT_NE(proxy, nullptr);
+    EXPECT_STREQ(proxy, "http://127.0.0.1:8000/");
+    free(proxy);
 }
 
 TEST(config, override_bypass_list) {
     proxy_config_set_bypass_list_override("<local>");
     char *bypass_list = proxy_config_get_bypass_list();
-    EXPECT_NE(bypass_list, nullptr);
-    if (bypass_list) {
-        EXPECT_STREQ(bypass_list, "<local>");
-        free(bypass_list);
-    }
+    ASSERT_NE(bypass_list, nullptr);
+    EXPECT_STREQ(bypass_list, "<local>");
+    free(bypass_list);
+}
+
+TEST(config, override_bypass_list_with_empt_list) {
+    proxy_config_set_bypass_list_override("");
+    char *bypass_list = proxy_config_get_bypass_list();
+    EXPECT_EQ(bypass_list, nullptr);
+    free(bypass_list);  // In case the condition above is not met
 }