sic v2 client WP6: resolveVerbs — map hops to verbs by nest depth, fail-loud on overflow

cmd/sic/addr.go

@@ -43,3 +43,21 @@ func verbFor(runtime, name string) (string, error) {
 		return "", fmt.Errorf("unknown runtime: %s", runtime)
 	}
 }
+
+func resolveVerbs(hops []string, nest []string) ([]string, error) {
+	if len(hops) > len(nest) {
+		return nil, fmt.Errorf("too many hops for this host's nest depth")
+	}
+	if len(hops) == 0 {
+		return []string{}, nil
+	}
+	verbs := make([]string, len(hops))
+	for i, hop := range hops {
+		verb, err := verbFor(nest[i], hop)
+		if err != nil {
+			return nil, err
+		}
+		verbs[i] = verb
+	}
+	return verbs, nil
+}

cmd/sic/resolveverbs_test.go

@@ -0,0 +1,32 @@
+package main
+
+import (
+	"reflect"
+	"testing"
+)
+
+// WP6: resolveVerbs maps each hop to its verb via verbFor, keyed by DEPTH in the host's nest.
+// Too many hops for the declared nest depth is a hard error (fail-loud); an unknown runtime
+// propagates verbFor's error. Zero hops -> zero verbs (a bare host is a single v2 frame).
+func TestResolveVerbs(t *testing.T) {
+	got, err := resolveVerbs([]string{"memory", "stash-stash-1"}, []string{"incus", "docker"})
+	if err != nil {
+		t.Fatalf("unexpected err: %v", err)
+	}
+	want := []string{"incus exec memory --", "docker exec stash-stash-1"}
+	if !reflect.DeepEqual(got, want) {
+		t.Fatalf("resolveVerbs = %#v, want %#v", got, want)
+	}
+
+	if v, err := resolveVerbs(nil, []string{"incus"}); err != nil || len(v) != 0 {
+		t.Fatalf("zero hops must yield zero verbs, no error; got %#v err %v", v, err)
+	}
+
+	if _, err := resolveVerbs([]string{"a", "b"}, []string{"incus"}); err == nil {
+		t.Fatal("more hops than the host's nest depth must be an error")
+	}
+
+	if _, err := resolveVerbs([]string{"x"}, []string{"bogus"}); err == nil {
+		t.Fatal("an unknown runtime must propagate verbFor's error")
+	}
+}