minor text fixes

README.md

@@ -1,35 +1,71 @@
-# CI On Modal
+# Run Continuous Integration Tests on Modal
 
 This repo is a demonstration of one pattern for running tests on Modal:
-bring your existing test suite and package (e.g. `my_pkg`), and add a Modal App (`my_pkg.ci`) and function (`.pytest`) that
+bring your existing package and test suite (here `my_pkg` and `tests`)
+and add a Modal App (`my_pkg.ci`)
+that mounts your tests
+and a Function (`pytest`) runs `pytest`.
 
-1. imports the code you want to test
-2. mounts your tests
-3. runs `pytest`
+That's as straightforward as
+
+```python
+# my_pkg/ci.py
+tests = modal.Mount.from_local_dir("path/to/tests", remote_path="/root/tests")
+
+
+@app.function(gpu="any", mounts=[tests])
+def pytest():
+    import subprocess
+
+    subprocess.run(["pytest", "-vs"], check=True, cwd="/root")
+```
 
 ## Setup
 
-- Create Python virtual environment
+- Create a Python virtual environment
 - `pip install modal`
+- That's it 😎
 
 ## Usage
 
 All commands below are run from the root of the repository.
 
 ### Run tests remotely on Modal
 
-This can be executed from inside another, cheaper CI runner, e.g. on GitHub Actions.
-
 ```bash
 modal run my_pkg.ci
 ```
 
-### Debug remote testing environment
+On the first execution, the [container image](https://modal.com/docs/guide/custom-container)
+for your application will be built.
+
+This image will be cached on Modal and only rebuilt if one of its dependencies,
+like the `requirements.txt` file, changes.
+
+### Run tests on Modal from GitHub Actions
+
+The same command can be executed from inside a CI runner on another platform.
+We provide a sample GitHub Actions workflow in `.github/workflows/ci.yml`.
+
+To run these tests on GitHub Actions, fork this repo and
+[create a new GitHub Actions secret](https://docs.github.com/en/actions/security-guides/using-secrets-in-github-actions)
+that contains your `MODAL_TOKEN_ID` and `MODAL_TOKEN_SECRET`.
+You can find this info in the `.modal.toml` file in your home directory.
+
+Now you can [manually trigger the tests to run on GitHub Actions](https://docs.github.com/en/actions/using-workflows/manually-running-a-workflow)
+or trigger them by making a change on our fork and pushing to `main` or making a pull request.
+
+### Debug tests running remotely
+
+To debug the tests, you can open a shell
+in the exact same environment that the tests are run in:
 
 ```bash
 modal shell my_pkg.ci
 ```
 
-I used the `shell` feature heavily while developing this pattern!
+We used the `shell` feature heavily while developing this pattern!
 
-_Note_: On the Modal worker, the `pytest` command is run from the home directory, `/root`, which contains the `tests` folder.
+_Note_: On the Modal worker, the `pytest` command is run from the home directory, `/root`,
+which contains the `tests` folder, but the `modal shell` command will
+drop you at the top of the filesystem, `/`.