internal/pkg: verify status kind

While it is still impossible to reliably determine the expected contents of these status files, this checks their nature for expected substitution behaviour.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/pkg/pkg_test.go

@@ -245,6 +245,30 @@ func newDestroyArtifactFunc(a pkg.Artifact) func(
 	}
 }
 
+// destroyStatus counts non-substitution status entries and destroys them.
+func destroyStatus(t *testing.T, base *check.Absolute, n int) {
+	dents, err := os.ReadDir(base.Append("status").String())
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	for _, dent := range dents {
+		if !dent.Type().IsRegular() {
+			t.Errorf("%s: %s", dent.Name(), dent.Type())
+		}
+		if err = os.Remove(base.Append(
+			"status",
+			dent.Name(),
+		).String()); err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	if len(dents) != n {
+		t.Errorf("ReadDir: %d entries, want %d", len(dents), n)
+	}
+}
+
 func TestIdent(t *testing.T) {
 	t.Parallel()
 
@@ -489,8 +513,9 @@ func checkWithCache(t *testing.T, testCases []cacheTestCase) {
 				}
 			}
 
-			// destroy non-deterministic status files
-			if err := os.RemoveAll(base.Append("status").String()); err != nil {
+			// destroy empty status directory
+			if err := syscall.Rmdir(base.Append("status").String()); err != nil {
+				t.Error(expectsFrom(base.Append("status").String()))
 				t.Fatal(err)
 			}