I've recently installed dirty-chai, which states:

The following built-in assertions are modified by this plugin to now use the function-call form:

The idea being, that hopefully, we get a fail in a test trying to run expect(true).to.be.true as it doesn't call the final property being accessed as a function.

But writing that test, gives me no such test failure.

I do note that the same doc also says:

These forms can also be mixed, but the chain must always be terminated in the function form or assertions up to that point in the chain will not execute.

_{emphasis mine}

However I have the code running with all of the below, and no test failures:

expect(true).to.be.true;
expect(true).to.be.ture;
expect(true).to.be.true();

I have dirty-chai installed like so, with Mocha 9.1.2, Chai 4.1.2, and the latest version of dirty-chai:

const Chai = require('chai');
const dirtyChai = require('dirty-chai');
....
Chai.use(dirtyChai);

this is all wrapped up in a javascript file that's passed to mocha via mocha <other options> -r ./test/chaiPlugins.js

Is dirty-chai not behaving as expected, or am I expecting it to behave in a way it doesn't?