fix(acp): fixtures now raise content mismatch errors

[codefromthecrypt]

Summary

Fix ACP test fixture to show clear error messages on content mismatch. Before, it returned empty string which defeated the logic involved.

Type of Change

• Bug fix
• Tests

AI Assistance

• This PR was created or reviewed with AI assistance

Testing

Introduced a typo and fixed the before and after issue

Related Issues

Relates to #6765

Diff

I introduced a typo (space) in the request match expression to trigger a failure.

Before

  json atoms at path "(root)" are not equal:                                                                                                                                           
      lhs:                                                                                                                                                                             
          ""                                                                                                                                                                           
      rhs:                                                                                                                                                                             
          {                                                                                                                                                                            
            "messages": [                                                                                                                                                              
              ...                                                                                                                                                                      

After:

  Expected body to contain:                                                                                                                                                            
    lookup[\"get_ code\"]({}): string - Get the code                                                                                                                                   
                                                                                                                                                                                       
  Actual body:                                                                                                                                                                         
    {"messages":[{"content":"You are a general-purpose AI agent called goose...     

[Copilot]

Pull request overview

This PR fixes a bug in the ACP test fixture error reporting. Previously, when request body matching failed, the fixture would pop the expected value from the queue before checking if it matched, causing error messages to show the wrong expected value (or empty string if queue was exhausted). This made debugging test failures very difficult.

Changes:

• Fixed queue handling to peek before popping, ensuring error messages show the correct expected value
• Replaced JSON diff error messages with simple, readable expected/actual format
• Improved panic propagation in test runner to show actual failure messages
• Made test assertions more precise with assert_eq! instead of contains checks

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
crates/goose-acp/tests/fixtures/mod.rs	Fixed queue peek-before-pop logic, removed assert_json_diff dependency, improved error message formatting, and fixed panic propagation in test runner
crates/goose-acp/tests/common_tests/mod.rs	Changed test assertions from contains to assert_eq! for more precise validation, added error checking for run_builtin_and_mcp test

[katzdave]

Did we lose something here with actual diff of the bodies together? Seems like we're only checking against empty.

[codefromthecrypt]

yeah the logic was wrong before as it was a substring search. So, what was happening is we were doing a diff of a substring vs an entire json body.

so it was doing a json diff of format!(r#"</info-msg>\n{prompt}""#) vs the actual json body.

This was a relic of an old version which did complete request matching, and is a bug in the current design. that's why json diff isn't useful here.

Make sense?

[katzdave]

Got it, thanks for clarifying!

[codefromthecrypt]

ps #6969