feat: add support for multiple fixture files in fixtures command

[cnaples79]

Summary

• Adds support for multiple fixture files to the fixtures command
• Allows users to run multiple fixtures in a single command
• Processes fixture files sequentially in the order provided

Rationale

Previously, users needed to chain multiple stripe fixtures commands using &&:

stripe fixtures ./subscription.created.json && stripe fixtures ./teardown.json

This change allows a simpler syntax:

stripe fixtures ./subscription.created.json ./teardown.json

This improves developer experience by reducing repetition and making it easier to run multiple fixtures together.

Changes Made

• pkg/cmd/fixtures.go:

  • Changed argument validator from ExactArgs(1) to MinimumNArgs(1) to accept one or more files
  • Added loop to process each fixture file sequentially
  • Each file is executed in order with proper error handling

• pkg/validators/cmds.go:

  • Implemented MinimumNArgs() validator function
  • Follows the same pattern as existing MaximumNArgs() and ExactArgs() validators
  • Provides clear error messages when too few arguments are provided

Test Plan

• Built the CLI successfully on Android/Linux (aarch64)
• Tested help output: ./stripe fixtures --help displays correctly
• Tested error handling: ./stripe fixtures shows appropriate error message
• Verified the binary compiles and runs correctly

The implementation maintains backward compatibility - single file usage continues to work as before.

Fixes #910

[cla-assistant[bot]]

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