assocPath.js

var assert = require('assert');

var R = require('../source/index.js');
var eq = require('./shared/eq.js');


describe('assocPath', function() {
  it('makes a shallow clone of an object, overriding only what is necessary for the path', function() {
    var obj1 = {a: {b: 1, c: 2, d: {e: 3}}, f: {g: {h: 4, i: [5, 6, 7], j: {k: 6, l: 7}}}, m: 8};
    var obj2 = R.assocPath(['f', 'g', 'i', 1], 42, obj1);
    eq(obj2.f.g.i, [5, 42, 7]);
    // Note: reference equality below!
    assert.strictEqual(obj2.a, obj1.a);
    assert.strictEqual(obj2.m, obj1.m);
    assert.strictEqual(obj2.f.g.h, obj1.f.g.h);
    assert.strictEqual(obj2.f.g.j, obj1.f.g.j);
  });

  it('is the equivalent of clone and setPath if the property is not on the original', function() {
    var obj1 = {a: 1, b: {c: 2, d: 3}, e: 4, f: 5};
    var obj2 = R.assocPath(['x', 0, 'y'], 42, obj1);
    eq(obj2, {a: 1, b: {c: 2, d: 3}, e: 4, f: 5, x: [{y: 42}]});
    // Note: reference equality below!
    assert.strictEqual(obj2.a, obj1.a);
    assert.strictEqual(obj2.b, obj1.b);
    assert.strictEqual(obj2.e, obj1.e);
    assert.strictEqual(obj2.f, obj1.f);
  });

  it('overwrites primitive values with keys in the path', function() {
    var obj1 = {a: 'str'};
    var obj2 = R.assocPath(['a', 'b'], 42, obj1);
    eq(obj2, {a: {b: 42}});
  });

  it('empty path replaces the whole object', function() {
    eq(R.assocPath([], 3, {a: 1, b: 2}), 3);
  });

  it('replaces `undefined` with a new object', function() {
    eq(R.assocPath(['foo', 'bar', 'baz'], 42, {foo: undefined}), {foo: {bar: {baz: 42}}});
  });

  it('replaces `null` with a new object', function() {
    eq(R.assocPath(['foo', 'bar', 'baz'], 42, {foo: null}), {foo: {bar: {baz: 42}}});
  });

  it('sets in indexes regardless of length', function() {
    eq(R.assocPath(['foo', 1, 0], 42, {foo : []}), {foo: [undefined, [42]]});
  });

  it('handles negative indexes from end of array', function() {
    eq(R.assocPath(['foo', -1], 42, {foo : [1, 2, 3]}), {foo: [1, 2, 42]});
    eq(R.assocPath(['foo', -1, 'X'], 42, {foo : [{a: 0}, {b: 0}]}), {foo: [{a: 0}, {b: 0, X: 42}]});
  });

  it('sets garbage key when negative indexes wraps to < 0', function() {
    var expected = [1, 2, 3];
    expected[-1] = 42;
    eq(R.assocPath(['foo', -4], 42, {foo : [1, 2, 3]}), {foo: expected});
  });
});