<function name="assert" parent="Global" type="libraryfunc"> <description>If the result of the first argument is false or nil, an error is thrown with the second argument as the message.</description> <realm>Shared and Menu</realm> <args> <arg name="expression" type="any">The expression to assert.</arg> <arg name="errorMessage" type="string" default="assertion failed!">The error message to throw when assertion fails. This is only type-checked if the assertion fails.</arg> <arg name="returns" type="vararg" default="nil">Any arguments past the error message will be returned by a successful assert.</arg> </args> <rets> <ret name="" type="any">If successful, returns the first argument.</ret> <ret name="" type="any">If successful, returns the error message. This will be nil if the second argument wasn't specified. Since the second argument is only type-checked if the assertion fails, this doesn't have to be a string.</ret> <ret name="" type="vararg">Returns any arguments past the error message.</ret> </rets> </function> <example> <description>The assertion is successful, and the result of the first argument is returned.</description> <code> local ABC = assert(print) print(ABC) </code> <output>function: builtin#25</output> </example> <example> <description>Since the first argument evaluates to false, an error is thrown.</description> <code>assert(print == 1, "print is not equal to 1!")</code> <output>[ERROR] lua_run:1: print is not equal to 1!</output> </example> <example> <description>Examples of return behaviour.</description> <code> print(assert(5)) print(assert(true, "foo", 2, {})) </code> <outputfixedwidth>Fixed width</outputfixedwidth>⤶ <output> ```⤶ 5 true foo 2 table: 0x36409278 ```⤶ </output> </example>