How to write Unit Test in cakephp 4.x.x

Hello, Thanks for your response. I know how to do integration tests, but this is not the point. I want to do Unit Tests. Let me give you an example of what I am trying to do and the test fails.
I have this link: $this->get(“localhost/myProject/Controller/action”);
In the response body this generates:

Signing document

When I try to assert: $this->assertResponseContains(‘Signing document’); It fails.
What am I doing wrong?