package buildstep

import "testing"

// The shared warm caches are read under a throwaway writable layer (novox/hq ADR 0448; issue 1309): a candidate's step
// writes into them as a build does, and nothing it writes outlives it or reaches a later build; only a trunk build
// writes them.
func TestACandidatesStepWritesTheCachesOnlyIntoAThrowawayLayer(t *testing.T) {
	fixedSystem(t)
	iso := Isolation{Workspace: "/w", Caches: []string{"/var/cache/go-build", "/var/cache/npm"}}
	argv, err := iso.Command("go", "test")
	if err != nil {
		t.Fatal(err)
	}
	for _, c := range iso.Caches {
		if !holds(argv, "--overlay-src", c, "--tmp-overlay", c) {
			t.Errorf("the cache %s is not under a throwaway layer: %v", c, argv)
		}
		if holds(argv, "--bind", c, c) {
			t.Errorf("a candidate's step writes the cache %s: %v", c, argv)
		}
	}
	iso.WriteCaches = true
	argv, _ = iso.Command("go", "build")
	for _, c := range iso.Caches {
		if !holds(argv, "--bind", c, c) || holds(argv, "--tmp-overlay", c) {
			t.Errorf("a trunk build does not write the cache %s: %v", c, argv)
		}
	}
}