Allow setting environment variables in setup hook

[Copilot]

Plan: Support passing env vars into test environment in setup

• Update SetupFn type alias in params.rs to accept &mut TestEnvironment instead of &TestEnvironment
• Update setup method signature in params.rs to accept Fn(&mut TestEnvironment) instead of Fn(&TestEnvironment)
• Update setup method signature in lib.rs Builder to accept Fn(&mut TestEnvironment) instead of Fn(&TestEnvironment)
• Update execution in execution.rs to pass &mut env to setup function
• Update existing test in setup_hook.rs to test the new functionality (make it pass)
• Add a new focused test to validate setting environment variables in setup hook
• Run tests to validate changes - all tests pass
• Update documentation examples to show the new capability
• Address code review feedback - fix trailing newline inconsistency
• Add comprehensive test for environment variable presence/absence to ensure proper isolation
• Enhance tests to demonstrate env vars work without sh -c wrapper (using printenv/set)
• Format assert statement to single line per style guidelines

Original prompt

---

This section details on the original issue you should resolve

<issue_title>support passing env vars into the test environment in setup</issue_title>
<issue_description>```
.setup(|env| => {
env.set("FOO", "bar")
}

(or similar)

this should make `FOO` have the value of `bar` in the test environment</issue_description>

## Comments on the Issue (you are @copilot in this section)

<comments>
</comments>

• Fixes support passing env vars into the test environment in setup #43

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[imjasonh]

@copilot Ensure there's a test that covers this behavior, to ensure envs which are set in setup are present in the test, and those that aren't set, are not available

[Copilot]

@copilot Ensure there's a test that covers this behavior, to ensure envs which are set in setup are present in the test, and those that aren't set, are not available

Added test_setup_env_vars_presence_and_absence() which verifies:

1. Environment variables set in setup (SET_VAR) are available in the test
2. Environment variables not set in setup (UNSET_VAR) are not available in the test

This ensures proper isolation of the test environment. Commit: 063cd77

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• 1.1.1.1
  • Triggering command: REDACTED, pid is -1 (packet block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

[imjasonh]

@copilot I want to mimic as much as possible (idiomatically for Rust) the behavior of https://pkg.go.dev/github.com/rogpeppe/go-internal/testscript#Env

Does that require sh -c to be able to get the values of the env? That library also supports env which just prints the full env vars, do we do that too?

[Copilot]

@copilot I want to mimic as much as possible (idiomatically for Rust) the behavior of https://pkg.go.dev/github.com/rogpeppe/go-internal/testscript#Env

Does that require sh -c to be able to get th...

Environment variables set in setup (or via env command) are passed directly to executed commands via Rust's .envs() - no sh -c needed for programs to access them (see updated test using printenv/set directly).

However, shell variable expansion syntax like $VAR requires a shell interpreter (sh -c or cmd /c), which matches idiomatic Rust behavior.

The env command already supports both behaviors from Go testscript:

• env (no args) prints all environment variables
• env VAR=value sets environment variables

Commit: 7282682

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• 1.1.1.1
  • Triggering command: REDACTED, pid is -1 (packet block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

[imjasonh]

@copilot

Diff in /home/runner/work/testscript-rs/testscript-rs/tests/setup_hook.rs:253:
     });
 
     let result = run_script(&script_path, &params);
-    assert!(
-        result.is_ok(),
-        "Env command test should pass: {:?}",
-        result
-    );
+    assert!(result.is_ok(), "Env command test should pass: {:?}", result);
 }

[Copilot]

@copilot

...

Fixed formatting to single line. Commit: 229e22d

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• 1.1.1.1
  • Triggering command: REDACTED, pid is -1 (packet block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)