kotlin.test / kotlin.test / assertTrue assertTrue Common JVM JS Native 1.0 @JvmName("assertTrueInline") inline fun assertTrue( message: String? = null, block: () -> Boolean): Unit(source) Asserts that the given block returns true. Common JVM JS Native 1.0 fun assertTrue( actual: Boolean, message: String? = null): Unit(source) Asserts that the expression is true with an optional message.