Make the test suite build its own binary, and create directories parents-first

[lancekrogers]

Why

The native release workflow added in the distribution work ran for the first time on main and failed immediately. main is currently red. Two independent defects, both of which the suite had been hiding.

1. The tests never actually ran the code under test

Five tests shelled out to a bare "tree2scaffold":

cmd := exec.Command("tree2scaffold", "-root", tmp, "-yes")

That resolves through $PATH, so on any machine with the tool installed in $GOBIN the suite passed — while testing the installed binary, not the working tree. CI has no such binary:

integration_checksum_test.go:306: scaffold failed:
  exec: "tree2scaffold": executable file not found in $PATH

A package-level TestMain now builds cmd/tree2scaffold once into a temp dir and every test invokes that. tree2scaffold_integration_test.go already did this correctly and now shares the one build instead of doing its own.

2. Directory creation order was randomised

With the PATH problem fixed, force_mode_with_hidden_files still failed — intermittently, which is why it had survived. Apply ranged over the directory set directly, and that set is a map:

for dir, isDir := range paths {

Go randomises map iteration. When .github/workflows came up before .github, and .github still existed as a file awaiting force conversion, MkdirAll failed with not a directory. It only lost the coin flip about half the time.

Measured before the fix — 5 runs of that one test on main, and on the branch with only fix #1 applied:

	result
main (pre-existing)	1 FAIL / 5
PATH fix only	2 FAIL / 5
both fixes, 8 full-suite runs	0 FAIL / 8

Sorting the directory list puts every parent ahead of its children, since a parent path is always a prefix of its child.

Test plan

• Full suite passes 8/8 with $GOBIN removed from PATH — i.e. under CI conditions
• New TestApplyCreatesParentsBeforeChildren repeats 50× (one pass would clear the old code ~half the time); verified it fails at iteration 0 against the unfixed code
• go vet clean, gofmt clean
• golangci-lint: 11 issues before, 11 after — all pre-existing, none added

Note

This does not touch the 11 pre-existing lint issues or the unused verifyGeneratedFilesUnused helper — separate cleanup.