internal/pkg: check exec substitution

This relies on the testtool having ident as relevant input to assert successful substitution.

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

internal/pkg/pkg_test.go

@@ -246,26 +246,37 @@ 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) {
+func destroyStatus(t *testing.T, base *check.Absolute, c, s int) {
 	dents, err := os.ReadDir(base.Append("status").String())
 	if err != nil {
 		t.Fatal(err)
 	}
 
+	var gotC, gotS int
 	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 dent.Type().IsRegular() {
+			gotC++
+			continue
+		}
+		if dent.Type()&fs.ModeSymlink == fs.ModeSymlink {
+			gotS++
+			continue
+		}
+		t.Errorf("%s: %s", dent.Name(), dent.Type())
 	}
 
-	if len(dents) != n {
-		t.Errorf("ReadDir: %d entries, want %d", len(dents), n)
+	if gotC != c {
+		t.Errorf("status: c = %d, want %d", gotC, c)
+	}
+	if gotS != s {
+		t.Errorf("status: s = %d, want %d", gotS, s)
 	}
 }