RICOCHET LEARN

Chapter 12: Testing, Linting, and Formatting

Why this chapter matters

Before you use files, HTTP, processes, UI surfaces, packages, or databases, you need a small feedback loop. Ricochet gives you assertions in code plus CLI commands for tests, linting, and formatting.

Testing answers “does this behavior still work?” Linting answers “does this source shape look suspicious?” Formatting answers “can this code be made consistent without changing behavior?”

What you will build

You will build the smallest feedback loop: assertions in a runnable file, then commands that scale that habit to tests, linting, formatting, and documentation checks.

Concepts in plain English

An assertion is a deliberate claim. If the claim is wrong, the run should fail. A linter points out likely mistakes. A formatter changes layout, not meaning. A test suite runs many assertions together.

Words and commands introduced

Primary coverage: rco test, rco lint, rco fmt, assertion helpers, and a high-level overview of @ricochet/test_helpers.

Guided example

Run the example:

bashrco run examples/learn/12-testing-linting-and-formatting/main.rco

The file uses assertion words directly:

ricochet40 2 + 42 assert_equals
true assert_true
false assert_false

For a single file, run the same feedback loop with lint and format:

bashrco lint examples/learn/12-testing-linting-and-formatting/main.rco
rco fmt examples/learn/12-testing-linting-and-formatting/main.rco --check

For a project or package, rco test PATH runs Ricochet test files under that path.

How to read the code

40 2 + 42 assert_equals computes 42, then compares it to the expected 42. The expected value appears just before the assertion word. If the actual and expected values differ, the assertion makes the run fail loudly.

Try it

Change 42 assert_equals to 41 assert_equals and run the example again. Read the failure, then restore the expected value.

Then try:

bashrco lint examples/learn/12-testing-linting-and-formatting/main.rco
rco fmt examples/learn/12-testing-linting-and-formatting/main.rco --check

Check your understanding

Common mistakes

What you know now

You know the basic safety loop before using advanced host powers: run a small program, assert the stack contract, lint the source, format separately, and test projects as they grow.