CLI: TableOutput unit tests

[dkbennett]

Summary of the Pull Request

Updates the table class slightly to make it easier for unit testing.
Adds unit tests to verify table output behavior.

PR Checklist

• Closes: Link to issue #xxx
• Communication: I've discussed this with core contributors already. If work hasn't been agreed, this work might be rejected
• Tests: Added/updated if needed and all pass
• Localization: All end user facing strings can be localized
• Dev docs: Added/updated if needed
• Documentation updated: If checked, please file a pull request on our docs repo and link it here: #xxx

Detailed Description of the Pull Request / Additional comments

Main change to tableoutput is adding a default output function and the ability to override it. The override is mainly for testing, but it may be useful in other contexts in the future.

Validation Steps Performed

Tests validated and passed

[Copilot]

Pull request overview

This PR makes TableOutput more unit-testable by adding injectable output and a console-width override, and introduces new CLI-focused unit tests to validate table rendering behavior.

Changes:

• Add an overridable output function to TableOutput (defaulting to stdout) to enable in-memory capture in tests.
• Add a console width override to make column-shrinking tests deterministic.
• Add a new unit test suite covering headers, padding, width expansion/truncation, shrinking, and IsEmpty().

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 5 comments.

File	Description
test/windows/wslc/WSLCCLITableOutputUnitTests.cpp	Adds unit tests for TableOutput rendering and sizing behavior using the new output injection hooks.
src/windows/wslc/core/TableOutput.h	Adds SetOutputFunction and SetConsoleWidthOverride, and routes rendered lines through the configured output function.

[Copilot]

The file header comment is inconsistent with the actual file name (Module Name says WSLCTableOutputUnitTests.cpp, but the file is WSLCCLITableOutputUnitTests.cpp) and the Abstract mentions redirecting output to a std::wstringstream, while the tests capture output via SetOutputFunction into a vector<wstring>. Please update the header comment to match the current test implementation to avoid confusion.

Suggested change

	WSLCTableOutputUnitTests.cpp
	Abstract:
	Unit tests for the TableOutput class.
	Output is redirected to an in-memory std::wstringstream so that tests
	are fully self-contained and do not depend on a real console or FILE*.
	WSLCCLITableOutputUnitTests.cpp
	Abstract:
	Unit tests for the TableOutput class.
	Output is captured via SetOutputFunction into an in-memory
	std::vector<std::wstring> so that tests are fully self-contained and do
	not depend on a real console or FILE*.

[Copilot]

This spacing assertion is too weak: statusPos > namePos + 3 can pass even when there are fewer than 3 spaces between the values (e.g., if ok starts immediately after abc plus 1 space). Consider asserting statusPos >= namePos + wcslen(L"abc") + columnPadding (or directly checking that the substring between the tokens contains the expected number of spaces).

Suggested change

	// Use a custom padding of 3 (the default) and verify the data row
	// contains at least 3 spaces between the first column value and the
	// start of the second column value.
	TableOutputCapture<2> cap(TableOutput<2>::header_t{L"NAME", L"STATUS"}, /*sizingBuffer=*/50, /*columnPadding=*/3);
	cap.table.OutputLine({L"abc", L"ok"});
	cap.table.Complete();
	// Data row: "abc" padded to header width ("NAME"=4) + 3 spaces, then "ok"
	// Expected: "abc ok" with appropriate spacing
	const std::wstring& dataLine = cap.lines[1];
	VERIFY_IS_TRUE(dataLine.find(L"abc") != std::wstring::npos);
	VERIFY_IS_TRUE(dataLine.find(L"ok") != std::wstring::npos);
	// There must be at least 3 spaces between the two values
	auto namePos = dataLine.find(L"abc");
	auto statusPos = dataLine.find(L"ok");
	VERIFY_IS_TRUE(statusPos > namePos + 3);
	constexpr size_t columnPadding = 3;
	constexpr wchar_t firstValue[] = L"abc";
	// Use a custom padding of 3 (the default) and verify the data row
	// contains at least 3 spaces between the first column value and the
	// start of the second column value.
	TableOutputCapture<2> cap(TableOutput<2>::header_t{L"NAME", L"STATUS"}, /*sizingBuffer=*/50, /*columnPadding=*/columnPadding);
	cap.table.OutputLine({firstValue, L"ok"});
	cap.table.Complete();
	// Data row: "abc" padded to header width ("NAME"=4) + 3 spaces, then "ok"
	// Expected: "abc ok" with appropriate spacing
	const std::wstring& dataLine = cap.lines[1];
	VERIFY_IS_TRUE(dataLine.find(firstValue) != std::wstring::npos);
	VERIFY_IS_TRUE(dataLine.find(L"ok") != std::wstring::npos);
	// There must be at least 3 spaces between the end of the first value
	// and the start of the second value.
	auto namePos = dataLine.find(firstValue);
	auto statusPos = dataLine.find(L"ok");
	constexpr size_t firstValueLength = (sizeof(firstValue) / sizeof(firstValue[0])) - 1;
	VERIFY_IS_TRUE(statusPos >= namePos + firstValueLength + columnPadding);

[dkbennett]

nice, copilot very good at this sort of thing

[Copilot]

The position calculation is off by one: to enforce 5-space padding after the x character, the start of y should be compared against posX + 1 + customPadding (the code currently uses posX + customPadding). Also, please assert posX != npos and posY != npos before doing arithmetic/comparisons; otherwise npos can wrap on addition and produce false positives.

Suggested change

	VERIFY_IS_TRUE(posY >= posX + customPadding);
	VERIFY_IS_TRUE(posX != std::wstring::npos);
	VERIFY_IS_TRUE(posY != std::wstring::npos);
	VERIFY_IS_TRUE(posY >= posX + 1 + customPadding);

[Copilot]

posOk is not validated before being compared. If find returns npos, the comparison can still pass (since npos is a very large size_t). Add VERIFY_IS_TRUE(posOk != std::wstring::npos) (or equivalent) before the range check to avoid false positives.

Suggested change

	auto posOk = dataLine.find(L"ok");
	auto posOk = dataLine.find(L"ok");
	VERIFY_IS_TRUE(posOk != std::wstring::npos);

[Copilot]

SetOutputFunction allows callers to pass an empty std::function (e.g. OutputFn{}), but OutputLineToStream unconditionally invokes m_outputFn(rendered), which will throw std::bad_function_call. Consider guarding against empty callables (reset to the default output if !fn), and/or providing a public way to restore the default output function (e.g. ResetOutputFunction() or making DefaultOutputFn() publicly accessible).

Suggested change

	// Override the output function (e.g. redirect to a stringstream in tests).
	void SetOutputFunction(OutputFn fn)
	{
	// Override the output function (e.g. redirect to a stringstream in tests).
	// Ignore empty callables so the current/default output function remains valid.
	void SetOutputFunction(OutputFn fn)
	{
	if (!fn)
	{
	return;
	}

[dkbennett]

I'll add an assert for this, we do not expect this to be used extensively or really at all outside tests at this time.

[AmelBawa-msft]

Should we move this to a shared/helper class? I think this will be helpful for E2E testing as well. Today we find image and container names in output lines. With this class, we can reconstruct the table and instead do VERIFY_ARE_EQUAL(rendered, stdout).

Alternatively, maybe the TableOutput class can have a ToString() that would give us the output as a string

[benhillis]

Hey @dkbennett 👋 — Following up on this draft PR. CI is green, but there are 6 unresolved review threads that still need to be addressed:

• File header mismatch
• Spacing assertion too weak
• Off-by-one in position calculation
• Missing \
  pos\ guards
• Empty function guard in \SetOutputFunction\
• Suggestion to move to a shared helper

Is this change still being worked on? It's been a few days since the last update. Let us know if you need any help with the review feedback!