fix(cmd): move file read from newInvokeConfig to runInvoke

[Elvand-Lie]

Fixes #3846

Problem

When --file is passed to func invoke, the file contents were read from disk twice:

1. In newInvokeConfig() — reads file into cfg.Data
2. In runInvoke() — reads the same file again into m.Data

The first read in newInvokeConfig() is problematic because it occurs before the --confirm interactive prompts. If the user changes the file path during these prompts, the original file data has already been loaded, causing stale data to be sent.

Changes

This PR removes the early file read and ensures the file is read only once, at the correct time:

• Removed early read: Eliminated the os.ReadFile block from newInvokeConfig().
• Relocated read logic: Moved the file read into runInvoke(), executing it after the configuration is finalized and immediately before client initialization for fail-fast behavior.
• Added testing: Introduced TestInvoke_FileFlag and TestInvoke_FileFlagNonExistent with sync.Mutex synchronization to explicitly test file-based invocation and error handling.

Testing

• TestInvoke_FileFlag — Verifies that providing a valid file correctly reads and sends its contents to the mock server.
• TestInvoke_FileFlagNonExistent — Verifies that providing a non-existent file path immediately returns the appropriate error.

[knative-prow]

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 53.44%. Comparing base (e7d7dcf) to head (4bce48d).
⚠️ Report is 8 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3847   +/-   ##
=======================================
  Coverage   53.44%   53.44%           
=======================================
  Files         200      200           
  Lines       23450    23406   -44     
=======================================
- Hits        12533    12510   -23     
+ Misses       9662     9648   -14     
+ Partials     1255     1248    -7     

Flag	Coverage Δ
e2e	33.69% <0.00%> (-0.03%)	⬇️
e2e go	29.59% <0.00%> (-0.07%)	⬇️
e2e node	25.89% <0.00%> (-0.07%)	⬇️
e2e python	29.93% <0.00%> (-0.07%)	⬇️
e2e quarkus	26.00% <0.00%> (-0.07%)	⬇️
e2e rust	25.40% <0.00%> (-0.14%)	⬇️
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e2e typescript	25.98% <0.00%> (-0.07%)	⬇️
e2e-config-ci	26.83% <0.00%> (+0.05%)	⬆️
integration	15.78% <0.00%> (+0.02%)	⬆️
unit macos-14	42.27% <100.00%> (+0.04%)	⬆️
unit macos-latest	42.27% <100.00%> (+0.04%)	⬆️
unit ubuntu-24.04-arm	42.56% <100.00%> (+0.03%)	⬆️
unit ubuntu-latest	43.13% <100.00%> (+0.04%)	⬆️
unit windows-latest	42.33% <100.00%> (+0.04%)	⬆️

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[gauron99]

The removed os.ReadFile in runInvoke() is the only code that reads the file after --confirm interactive prompts may have changed cfg.File. Two scenarios break:

1. func invoke --file=a.txt --confirm → user changes file to b.txt in the prompt → a.txt contents get sent
2. func invoke --confirm → user types mydata.txt in the File prompt → file is never read, default {"message":"Hello World"} gets sent

I suspect the first if cfg.File != "" read is actually redundant. We want to read the file after the whole config is constructed and its values finalized. The first read in newInvokeConfig() most likely served a purpose of displaying data from a file if it was already provided previously, but if File is provided the Data prompt is skipped entirely. There might be some simplification possible here. Make sure to test this locally and if no integration tests exist, create them.

[gauron99]

/assign

[knative-prow]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: Elvand-Lie
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[Elvand-Lie]

@gauron99 Right. Since this was meant to be a cleanup, I saw the two os.ReadFile blocks and assumed the second one in runInvoke() was redundant because cfg.Data was already populated. I didn't account for the interactive --confirm prompts mutating cfg.File between the two reads, meaning the first read pulls stale data. My bad.

I've pushed a fix:

1. Removed the early read from newInvokeConfig().
2. Moved the os.ReadFile back into runInvoke() so it reads the file only after the config and prompts are finalized.
3. Added TestInvoke_FileFlag and TestInvoke_FileFlagNonExistent to explicitly test this behavior against the mock runner.
4. Fixed formatting with goimports to pass the CI style check.

[Copilot]

Pull request overview

Removes redundant disk I/O when func invoke --file ... is used by ensuring the file contents are only read once and used as the invocation payload.

Changes:

• Moves --file reading logic so the invocation message data is populated from a single read.
• Removes the previous duplicated/now-unnecessary file-read logic.
• Adds unit tests covering --file success and missing-file error behavior.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
cmd/invoke.go	Refactors when/where --file is read to avoid redundant reads and feed cfg.Data into the invoke message.
cmd/invoke_test.go	Adds tests validating --file payload handling and error reporting for missing files.

Comments suppressed due to low confidence (1)

cmd/invoke.go:287

• Reading the file in runInvoke means cfg.Data is still the flag-provided "data" value during newInvokeConfig(). In --confirm non-interactive mode, the command prints Data: before this read happens, so the confirmation output can be misleading when --file is set. Consider loading the file into cfg.Data inside newInvokeConfig after any interactive prompts have completed (and before printing/returning), and then avoid mutating cfg later in runInvoke.

	switch strings.ToLower(cfg.Format) {
	case "cloudevent", "cloudevents":
		cfg.Format = "cloudevent"
	}

	// if not in confirm/prompting mode, the cfg structure is complete.
	if !cfg.Confirm {
		return

---

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