Add support for configuring k6-jslib-testing via the environment

[oleiade]

Introduces support for the K6_TESTING_COLORIZE, K6_TESTING_DISPLAY, K6_TESTING_TIMEOUT and K6_TESTING_INTERVAL environment variables to configure the expect keyword accordingly. Precedence, from higher to lower is env > js configure call > defaults.

See README for documentation.

[Copilot]

Copilot reviewed 5 out of 7 changed files in this pull request and generated 1 comment.

Files not reviewed (2)

• README.md: Evaluated as low risk
• environment.ts: Evaluated as low risk

Copilot reviewed 5 out of 7 changed files in this pull request and generated no comments.

Files not reviewed (2)

• README.md: Evaluated as low risk
• config.test.ts: Evaluated as low risk

Comments suppressed due to low confidence (2)

environment.ts:54

• The enum function converts the environment variable value to lowercase, which may not be intended if the environment variables are case-sensitive. Consider removing the .toLowerCase() conversion.

const value = env[key]?.toLowerCase() as T;

environment.ts:87

• [nitpick] The error message should be more specific about the requirement for a non-negative number. Consider changing it to: Environment variable ${name} must be a non-negative number (>= 0), got: ${value}.

throw new Error(`Environment variable ${name} must be a non-negative number, got: ${value}`);