use deepfield for associative key checck

merge2_test.go

	{`nested associative -- add same name, different path`,
		`
kind: Deployment
volumes:
- name: vol1
  projected:
    sources:
    - secret:
        name: source1
        optional: false
`,
		`
kind: Deployment
volumes:
- name: vol1
  projected:
    sources:
    - configMap:
        name: source1
        optional: false
`,
		`
kind: Deployment
volumes:
- name: vol1
  projected:
    sources:
    - configMap:
        name: source1
        optional: false
    - secret:
        name: source1
        optional: false
`,
	},

types.go

// checkKey returns true if all elems have the key
func checkKey(key string, elems []*Node) bool {
	count := 0
	paths := [][]string{}
	for i := range elems {
		elem := NewRNode(elems[i])
		path, mn := elem.DeepField(key)
		if mn != nil {
			count++
			paths = append(paths, path)
		}
	}

	// Make sure all elems have the key.
	if count != len(elems) {
		return false
	}

	// Make sure nested keys have the same path depth.
	depth := len(paths[0])
	for i := range paths {
		if len(paths[i]) != depth {
			return false
		}
	}

	// fmt.Fprintf(os.Stderr, "key: %v\n", key)
	for i := range paths {
		fmt.Fprintf(os.Stderr, "path: %v\n", strings.Join(paths[i], "."))
	}
	return true
}