feat: Prevent unused flags (#4182)

* Prevent unused flags

* Better verbiage

* Implementation for preventing unused flags

* Change comments and verbiage

cmd/server_test.go

@@ -213,6 +213,32 @@ func TestExecute_Flags(t *testing.T) {
 	}
 }
 
+func TestUserConfigAllTested(t *testing.T) {
+	t.Log("All settings in userConfig should be tested.")
+
+	u := reflect.TypeOf(server.UserConfig{})
+
+	for i := 0; i < u.NumField(); i++ {
+
+		userConfigKey := u.Field(i).Tag.Get("mapstructure")
+		t.Run(userConfigKey, func(t *testing.T) {
+			// By default, we expect all fields in UserConfig to have flags defined in server.go and tested here in server_test.go
+			// Some fields are too complicated to have flags, so are only expressible in the config yaml
+			flagKey := u.Field(i).Tag.Get("flag")
+			if flagKey == "false" {
+				return
+			}
+			// If a setting is configured in server.UserConfig, it should be tested here. If there is no corresponding const
+			// for specifying the flag, that probably means one *also* needs to be added to server.go
+			if _, ok := testFlags[userConfigKey]; !ok {
+				t.Errorf("server.UserConfig has field with mapstructure %s that is not tested, and potentially also not configured as a flag. Either add it to testFlags (and potentially as a const in cmd/server), or remove it from server.UserConfig", userConfigKey)
+			}
+		})
+
+	}
+
+}
+
 func TestExecute_ConfigFile(t *testing.T) {
 	t.Log("Should use all the values from the config file.")
 	// Use yaml package to quote values that need quoting

server/user_config.go

@@ -108,7 +108,7 @@ type UserConfig struct {
 	VarFileAllowlist           string          `mapstructure:"var-file-allowlist"`
 	VCSStatusName              string          `mapstructure:"vcs-status-name"`
 	DefaultTFVersion           string          `mapstructure:"default-tf-version"`
-	Webhooks                   []WebhookConfig `mapstructure:"webhooks"`
+	Webhooks                   []WebhookConfig `mapstructure:"webhooks" flag:"false"`
 	WebBasicAuth               bool            `mapstructure:"web-basic-auth"`
 	WebUsername                string          `mapstructure:"web-username"`
 	WebPassword                string          `mapstructure:"web-password"`