所有Codeception gherkin .feature测试最终都会出现在Context文件中吗？

Moving to Codeception from Behat and still getting used to it's concepts & where things go.

In the hypothetical that my tests are 100% driven from .feature files, does this mean that all of the test code could be in Contexts? That there wouldn't be anything in any functional tests that extend PHPUnit_Framework_TestCase? (Assuming that all my functional tests would extend that)

Codeception is not driven by Gherkin as Behat is. If you are moving away from Behat you will write functions in classes in Codeception directly and you are not going to start from a Gherkin script to then derive the executable specs (in your contexts files, page objects).

In brief the two flows

Behat

1. Write the BDD scripts/Gherkin - features. These are totally abstract and should usually be logic descriptions of the use cases your system implements. A product owner can start writing this for instance when a user story is created. Requires no programming logic
2. For each line in the feature implement an executable specification (a function in a Context class) that handles that action
3. In Behat usually you also use Page objects (unsure if this can also be done in Codeception but I dont see why not if you can import the Page Object library)

Codeception

1. You write executable specifications as a first step for instance in a Cept class. A developer is needed here as this is actual PHP Code/Classes
2. When you run codeception then it prints out a list of all the statements it has run, just like a report.

The above is a very simplified description as your question is also very generic. I hope it answers your question