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Creating a reusable test-writing command

Reviewing auth.ts revealed that the session functions aren't tested yet—likely your next task. Since you'll be writing similar Vitest tests across the codebase, automate the workflow with a custom slash command. Save the common instructions in .claude/commands/write_tests.md using a $ARGUMENTS placeholder, then run /write_tests path/to/file.ts whenever you need tests for a file.

Note: Newer Claude Code versions pick up new commands automatically without a restart. The version used in this exercise environment still requires the /exit and restart shown here.

This exercise is part of the course

Claude Code in Action

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Exercise instructions

  • Start Claude Code with claude.
  • Ask Claude to create a custom command at .claude/commands/write_tests.md that uses $ARGUMENTS to write Vitest tests for the file the learner names.
  • Type /exit to exit Claude Code.

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