Support invocation of mockgen via go tool with new write generate directive

[smlx]

What?

This change adds a new flag: -write_tool_generate_directive, which correctly handles invocation of mockgen via go tool in //go:generate directives.

Why?

The problem this fixes is using go tool mockgen to invoke mockgen in a //go:generate directive.

For example if I have a mock file with a //go:generate directive like this:

//go:generate go tool mockgen -destination ./mock_handler_test.go -write_generate_directive ...

Then it will be regenerated something like this:

//go:generate /home/scott/.cache/go-build/2b/2bdd48bc50b1532a85e833a029839a9b1e94233556b3072b236f31813080f176-d/mockgen -destination ./mock_handler_test.go -write_generate_directive ...

The new -write_tool_generate_directive flag introduced in this PR works the same way as the -write_generate_directive flag, except that it correctly regenerates "go tool mockgen" invocations of the mockgen tool. So this will now be correctly regenerated:

//go:generate go tool mockgen -destination ./mock_handler_test.go -write_tool_generate_directive ...

Alternatives considered

It would be nice to detect when mockgen is being invoked by go tool instead of being executed directly, because then you could add go tool mockgen support directly to the existing -write_generate_directive. But I couldn't find any simple way to detect when the tool is being called via go tool mockgen.

Summary by CodeRabbit

• New Features
  • Introduced a new command-line option that lets you specify an alternative mock generation directive when using the tool indirectly.
• Enhancements
  • Improved validation now ensures that only one directive option is used at a time, with clear error feedback for conflicting settings.

[CLAassistant]

All committers have signed the CLA.

[coderabbitai[bot]]

Walkthrough

The update introduces a new command-line flag writeToolGenerateDirective alongside an existing flag writeGenerateDirective in the mockgen tool. The tool now enforces mutual exclusivity between these flags and returns an error if both are set. Additionally, the Generate method has been modified to handle the new flag by applying a different output formatting condition when it is used.

Changes

File(s)	Change Summary
mockgen/…/mockgen.go	- Added new flag writeToolGenerateDirective of type *bool - Updated writeGenerateDirective logic to enforce mutual exclusivity and return an error when both are set - Modified Generate method to conditionally format output based on the new flag

Sequence Diagram(s)

sequenceDiagram
    participant User
    participant CLI
    participant GenerateMethod

    User->>CLI: Run mockgen with flags
    CLI->>GenerateMethod: Invoke Generate(flag settings)
    alt Both flags are set
        GenerateMethod->>User: Return error for mutually exclusive flags
    else Flag writeToolGenerateDirective is set
        GenerateMethod->>GenerateMethod: Format output using tool directive
    else Flag writeGenerateDirective is set
        GenerateMethod->>GenerateMethod: Format output using generate directive
    end

Poem

I'm a small rabbit with a curious mind,
Hopping through code where flags unwind.
Two directives dance in a delicate play,
One must lead, the other stands away.
With whiskers twitching at every change,
I celebrate these updates on my coding range!
🐇✨

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📜 Recent review details

Configuration used: CodeRabbit UI Review profile: CHILL Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 6568d888c79f7c03d45c396af40b608782fae4df and 26e33b327ee7755a3a06d57dc0f6bd98d64bc250.

📒 Files selected for processing (1)

• mockgen/mockgen.go (2 hunks)

🔇 Additional comments (2)

mockgen/mockgen.go (2)

66-66: Good addition of a flag for supporting go tool invocation.

The new flag writeToolGenerateDirective clearly addresses the issue with regenerating directives when mockgen is invoked via go tool.

---

441-449: Nice implementation of the mutual exclusivity check.

The switch statement properly handles the new logic:

1. Returns an error if both flags are specified
2. Maintains existing behavior for writeGenerateDirective
3. Implements the new behavior for writeToolGenerateDirective by correctly formatting the command with go tool

This effectively solves the issue with incorrect directives when invoked through go tool.

✨ Finishing Touches

• [ ] 📝 Generate Docstrings

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[smlx]

The CLA tool doesn't seem to load for me.. :confused:

edit: came back the next day and it was back up