import ConfigurationError from "./configuration-error" ; describe ( "ConfigurationError" , function ( ) { it ( "can be identified using `instanceof`" , function ( ) { const configError = new ConfigurationError ( "foobar" ) ; expect ( configError instanceof ConfigurationError ) . toEqual ( true ) ; const error = new Error ( "foobar" ) ; expect ( error instanceof ConfigurationError ) . toEqual ( false ) ; } ) ; it ( "`message` property equals first constructor argument" , function ( ) { const error = new ConfigurationError ( "foobar" ) ; expect ( error . message ) . toEqual ( "foobar" ) ; } ) ; } ) ;