refactor(lodash): merge (algolia/algoliasearch-helper-js#694)

* test(merge): original lodash tests

* refactor(lodash): merge

disable some tests we don't want to comply to

* docs(merge): add jsdoc

* test: remove skipped tests

* test: rewrite title

packages/algoliasearch-helper/src/SearchParameters/index.js

@@ -1,7 +1,6 @@
 'use strict';
 
-var merge = require('lodash/merge');
-
+var merge = require('../functions/merge');
 var defaultsPure = require('../functions/defaultsPure');
 var find = require('../functions/find');
 var valToNumber = require('../functions/valToNumber');

packages/algoliasearch-helper/src/SearchResults/index.js

@@ -1,7 +1,6 @@
 'use strict';
 
-var merge = require('lodash/merge');
-
+var merge = require('../functions/merge');
 var defaultsPure = require('../functions/defaultsPure');
 var orderBy = require('../functions/orderBy');
 var compact = require('../functions/compact');

packages/algoliasearch-helper/src/functions/merge.js

@@ -0,0 +1,58 @@
+'use strict';
+
+function clone(value) {
+  if (typeof value === 'object' && value !== null) {
+    return merge(Array.isArray(value) ? [] : {}, value);
+  }
+  return value;
+}
+
+/**
+ * This method is like Object.assign, but recursively merges own and inherited
+ * enumerable keyed properties of source objects into the destination object.
+ *
+ * NOTE: this behaves like lodash/merge, but:
+ * - does mutate functions if they are a source
+ * - treats non-plain objects as plain
+ * - does not work for circular objects
+ * - treats sparse arrays as sparse
+ * - does not convert Array-like objects to arrays
+ *
+ * @param {Object} object The destination object.
+ * @param {...Object} [sources] The source objects.
+ * @returns {Object} Returns `object`.
+ */
+function merge() {
+  var sources = Array.prototype.slice.call(arguments);
+  var target = sources.shift();
+
+  return sources.reduce(function(acc, source) {
+    if (acc === source) {
+      return acc;
+    }
+
+    if (source === undefined) {
+      return acc;
+    }
+
+    if (acc === undefined) {
+      return clone(source);
+    }
+
+    if (typeof acc !== 'object' && typeof acc !== 'function') {
+      return clone(source);
+    }
+
+    if (typeof source !== 'object' && typeof source !== 'function') {
+      return acc;
+    }
+
+    Object.keys(source).forEach(function(key) {
+      acc[key] = merge(acc[key], source[key]);
+    });
+
+    return acc;
+  }, target);
+}
+
+module.exports = merge;

packages/algoliasearch-helper/src/requestBuilder.js

@@ -1,6 +1,6 @@
 'use strict';
 
-var merge = require('lodash/merge');
+var merge = require('./functions/merge');
 
 var requestBuilder = {
   /**
@@ -72,7 +72,7 @@ var requestBuilder = {
       additionalParams.numericFilters = numericFilters;
     }
 
-    return merge(state.getQueryParams(), additionalParams);
+    return merge({}, state.getQueryParams(), additionalParams);
   },
 
   /**
@@ -117,7 +117,7 @@ var requestBuilder = {
       additionalParams.facetFilters = facetFilters;
     }
 
-    return merge(state.getQueryParams(), additionalParams);
+    return merge({}, state.getQueryParams(), additionalParams);
   },
 
   /**
@@ -310,8 +310,11 @@ var requestBuilder = {
     if (typeof maxFacetHits === 'number') {
       searchForFacetSearchParameters.maxFacetHits = maxFacetHits;
     }
-    var queries = merge(requestBuilder._getHitsSearchParams(stateForSearchForFacetValues), searchForFacetSearchParameters);
-    return queries;
+    return merge(
+      {},
+      requestBuilder._getHitsSearchParams(stateForSearchForFacetValues),
+      searchForFacetSearchParameters
+    );
   }
 };
 

packages/algoliasearch-helper/test/spec/functions/merge.js

@@ -0,0 +1,173 @@
+'use strict';
+const merge = require('../../../src/functions/merge');
+
+it('should merge `source` into `object`', function() {
+  var names = {
+    characters: [{name: 'barney'}, {name: 'fred'}]
+  };
+
+  var ages = {
+    characters: [{age: 36}, {age: 40}]
+  };
+
+  var heights = {
+    characters: [{height: '5\'4"'}, {height: '5\'5"'}]
+  };
+
+  var expected = {
+    characters: [
+      {name: 'barney', age: 36, height: '5\'4"'},
+      {name: 'fred', age: 40, height: '5\'5"'}
+    ]
+  };
+
+  expect(merge(names, ages, heights)).toEqual(expected);
+});
+
+it('should work with four arguments', function() {
+  var expected = {a: 4};
+  var actual = merge({a: 1}, {a: 2}, {a: 3}, expected);
+
+  expect(actual).toEqual(expected);
+});
+
+it('should merge onto function `object` values', function() {
+  function Foo() {}
+
+  var source = {a: 1};
+  var actual = merge(Foo, source);
+
+  expect(actual).toEqual(Foo);
+  expect(Foo.a).toEqual(1);
+});
+
+it('should merge first source object properties to function', function() {
+  var fn = function() {};
+  var object = {prop: {}};
+  var actual = merge({prop: fn}, object);
+
+  expect(actual.prop).toBeInstanceOf(Function);
+});
+
+// TODO: differs from lodash, but seems to make more sense to me
+it('should merge first and second source object properties to function', function() {
+  var fn = function() {};
+  var object = {prop: {dogs: 'out'}};
+  var actual = merge({prop: fn}, {prop: fn}, object);
+
+  expect(actual.prop).toBe(fn);
+  expect(actual.prop.dogs).toBe('out');
+});
+
+it('should merge onto non-plain `object` values', function() {
+  function Foo() {}
+
+  var object = new Foo();
+  var actual = merge(object, {a: 1});
+
+  expect(actual).toBe(object);
+  expect(object.a).toBe(1);
+});
+
+it('should assign `null` values', function() {
+  var actual = merge({a: 1}, {a: null});
+  expect(actual.a).toBe(null);
+});
+
+it('should not augment source objects for inner objects', function() {
+  var source1 = {a: [{a: 1}]};
+  var source2 = {a: [{b: 2}]};
+  var actual = merge({}, source1, source2);
+
+  expect(source1.a).toEqual([{a: 1}]);
+  expect(source2.a).toEqual([{b: 2}]);
+  expect(actual.a).toEqual([{a: 1, b: 2}]);
+});
+
+it('should not augment source objects for inner arrays', function() {
+  var source1 = {a: [[1, 2, 3]]};
+  var source2 = {a: [[3, 4]]};
+  var actual = merge({}, source1, source2);
+
+  expect(source1.a).toEqual([[1, 2, 3]]);
+  expect(source2.a).toEqual([[3, 4]]);
+  expect(actual.a).toEqual([[3, 4, 3]]);
+});
+
+it('should merge plain objects onto non-plain objects', function() {
+  function Foo(object) {
+    Object.assign(this, object);
+  }
+
+  var object = {a: 1};
+  var actual = merge(new Foo(), object);
+
+  expect(actual instanceof Foo).toBe(true);
+  expect(actual).toEqual(new Foo(object));
+
+  actual = merge([new Foo()], [object]);
+  expect(actual[0] instanceof Foo).toBe(true);
+  expect(actual).toEqual([new Foo(object)]);
+});
+
+it('should not overwrite existing values with `undefined` values of object sources', function() {
+  var actual = merge({a: 1}, {a: undefined, b: undefined});
+  expect(actual).toEqual({a: 1, b: undefined});
+});
+
+it('should not overwrite existing values with `undefined` values of array sources', function() {
+  var array = [1];
+  array[2] = 3;
+
+  var actual = merge([4, 5, 6], array);
+  var expected = [1, 5, 3];
+
+  expect(actual).toEqual(expected);
+
+  array = [1, undefined, 3];
+
+  actual = merge([4, 5, 6], array);
+  expect(actual).toEqual(expected);
+});
+
+it('should skip merging when `object` and `source` are the same value', function() {
+  var object = {};
+  var pass = true;
+
+  Object.defineProperty(object, 'a', {
+    configurable: true,
+    enumerable: true,
+    get: function() {
+      pass = false;
+    },
+    set: function() {
+      pass = false;
+    }
+  });
+
+  merge(object, object);
+  expect(pass).toBe(true);
+});
+
+it('should not convert objects to arrays when merging arrays of `source`', function() {
+  var object = {a: {'1': 'y', 'b': 'z', 'length': 2}};
+  var actual = merge(object, {a: ['x']});
+
+  expect(actual).toEqual({a: {
+    '0': 'x',
+    '1': 'y',
+    'b': 'z',
+    'length': 2
+  }});
+
+  actual = merge({a: {}}, {a: []});
+  expect(actual).toEqual({a: {}});
+});
+
+it('should not convert strings to arrays when merging arrays of `source`', function() {
+  var object = {a: 'abcde'};
+  var actual = merge(object, {a: ['x', 'y', 'z']});
+
+  expect(actual).toEqual({a: ['x', 'y', 'z']});
+});
+