Allow deepEqual fonction to be configured globally

lib/chai/assertion.js

@@ -40,6 +40,8 @@ import * as util from './utils/index.js';
  *   from within another assertion. It's also temporarily set to `true` before
  *   an overwritten assertion gets called by the overwriting assertion.
  *
+ * - `eql`: This flag contains the deepEqual function to be used by the assertion.
+ *
  * @param {Mixed} obj target of the assertion
  * @param {String} msg (optional) custom error message
  * @param {Function} ssfi (optional) starting point for removing stack frames
@@ -52,6 +54,7 @@ export function Assertion (obj, msg, ssfi, lockSsfi) {
   util.flag(this, 'lockSsfi', lockSsfi);
   util.flag(this, 'object', obj);
   util.flag(this, 'message', msg);
+  util.flag(this, 'eql', config.deepEqual ?? util.eql);
 
   return util.proxify(this);
 }

lib/chai/config.js

@@ -90,5 +90,31 @@ export const config = {
    * @api public
    */
 
-  proxyExcludedKeys: ['then', 'catch', 'inspect', 'toJSON']
+  proxyExcludedKeys: ['then', 'catch', 'inspect', 'toJSON'],
+
+  /**
+   * ### config.deepEqual
+   *
+   * User configurable property, defines which a custom function to use for deepEqual
+   * comparisons.
+   * By default, the function used is the one from the `deep-eql` package without custom comparator.
+   *
+   *     // use a custom comparator
+   *     chai.config.deepEqual = (expected, actual) => {
+   *        return chai.util.eql(expected, actual, {
+   *           comparator: (expected, actual) => {
+   *              // for non number comparison, use the default behavior
+   *              if(typeof expected !== 'number') return null;
+   *              // allow a difference of 10 between compared numbers
+   *              return typeof actual === 'number' && Math.abs(actual - expected) < 10
+   *           }
+   *        })
+   *     };
+   *
+   * @param {Function}
+   * @api public
+   */
+
+  deepEqual: null
+
 };

lib/chai/core/assertions.js

@@ -479,7 +479,8 @@ function include (val, msg) {
     , negate = flag(this, 'negate')
     , ssfi = flag(this, 'ssfi')
     , isDeep = flag(this, 'deep')
-    , descriptor = isDeep ? 'deep ' : '';
+    , descriptor = isDeep ? 'deep ' : ''
+    , isEql = isDeep ? flag(this, 'eql') : SameValueZero;
 
   flagMsg = flagMsg ? flagMsg + ': ' : '';
 
@@ -503,7 +504,6 @@ function include (val, msg) {
       break;
 
     case 'map':
-      var isEql = isDeep ? _.eql : SameValueZero;
       obj.forEach(function (item) {
         included = included || isEql(item, val);
       });
@@ -512,7 +512,7 @@ function include (val, msg) {
     case 'set':
       if (isDeep) {
         obj.forEach(function (item) {
-          included = included || _.eql(item, val);
+          included = included || isEql(item, val);
         });
       } else {
         included = obj.has(val);
@@ -522,7 +522,7 @@ function include (val, msg) {
     case 'array':
       if (isDeep) {
         included = obj.some(function (item) {
-          return _.eql(item, val);
+          return isEql(item, val);
         })
       } else {
         included = obj.indexOf(val) !== -1;
@@ -1094,8 +1094,9 @@ Assertion.addMethod('eq', assertEqual);
 
 function assertEql(obj, msg) {
   if (msg) flag(this, 'message', msg);
+  var eql = flag(this, 'eql');
   this.assert(
-      _.eql(obj, flag(this, 'object'))
+      eql(obj, flag(this, 'object'))
     , 'expected #{this} to deeply equal #{exp}'
     , 'expected #{this} to not deeply equal #{exp}'
     , obj
@@ -1863,7 +1864,8 @@ function assertProperty (name, val, msg) {
   var isDeep = flag(this, 'deep')
     , negate = flag(this, 'negate')
     , pathInfo = isNested ? _.getPathInfo(obj, name) : null
-    , value = isNested ? pathInfo.value : obj[name];
+    , value = isNested ? pathInfo.value : obj[name]
+    , isEql = isDeep ? flag(this, 'eql') : (val1, val2) => val1 === val2;
 
   var descriptor = '';
   if (isDeep) descriptor += 'deep ';
@@ -1890,7 +1892,7 @@ function assertProperty (name, val, msg) {
 
   if (arguments.length > 1) {
     this.assert(
-        hasProperty && (isDeep ? _.eql(val, value) : val === value)
+      hasProperty && isEql(val, value)
       , 'expected #{this} to have ' + descriptor + _.inspect(name) + ' of #{exp}, but got #{act}'
       , 'expected #{this} to not have ' + descriptor + _.inspect(name) + ' of #{act}'
       , val
@@ -2038,9 +2040,10 @@ function assertOwnPropertyDescriptor (name, descriptor, msg) {
   if (msg) flag(this, 'message', msg);
   var obj = flag(this, 'object');
   var actualDescriptor = Object.getOwnPropertyDescriptor(Object(obj), name);
+  var eql = flag(this, 'eql');
   if (actualDescriptor && descriptor) {
     this.assert(
-        _.eql(descriptor, actualDescriptor)
+        eql(descriptor, actualDescriptor)
       , 'expected the own property descriptor for ' + _.inspect(name) + ' on #{this} to match ' + _.inspect(descriptor) + ', got ' + _.inspect(actualDescriptor)
       , 'expected the own property descriptor for ' + _.inspect(name) + ' on #{this} to not match ' + _.inspect(descriptor)
       , descriptor
@@ -2394,7 +2397,8 @@ function assertKeys (keys) {
   var len = keys.length
     , any = flag(this, 'any')
     , all = flag(this, 'all')
-    , expected = keys;
+    , expected = keys
+    , isEql = isDeep ? flag(this, 'eql') : (val1, val2) => val1 === val2;
 
   if (!any && !all) {
     all = true;
@@ -2404,11 +2408,7 @@ function assertKeys (keys) {
   if (any) {
     ok = expected.some(function(expectedKey) {
       return actual.some(function(actualKey) {
-        if (isDeep) {
-          return _.eql(expectedKey, actualKey);
-        } else {
-          return expectedKey === actualKey;
-        }
+        return isEql(expectedKey, actualKey);
       });
     });
   }
@@ -2417,11 +2417,7 @@ function assertKeys (keys) {
   if (all) {
     ok = expected.every(function(expectedKey) {
       return actual.some(function(actualKey) {
-        if (isDeep) {
-          return _.eql(expectedKey, actualKey);
-        } else {
-          return expectedKey === actualKey;
-        }
+        return isEql(expectedKey, actualKey);
       });
     });
 
@@ -3109,7 +3105,7 @@ Assertion.addMethod('members', function (subset, msg) {
     failNegateMsg = 'expected #{this} to not have the same ' + subject + ' as #{exp}';
   }
 
-  var cmp = flag(this, 'deep') ? _.eql : undefined;
+  var cmp = flag(this, 'deep') ? flag(this, 'eql') : undefined;
 
   this.assert(
       isSubsetOf(subset, obj, cmp, contains, ordered)
@@ -3165,7 +3161,8 @@ function oneOf (list, msg) {
     , flagMsg = flag(this, 'message')
     , ssfi = flag(this, 'ssfi')
     , contains = flag(this, 'contains')
-    , isDeep = flag(this, 'deep');
+    , isDeep = flag(this, 'deep')
+    , eql = flag(this, 'eql');
   new Assertion(list, flagMsg, ssfi, true).to.be.an('array');
 
   if (contains) {
@@ -3179,7 +3176,7 @@ function oneOf (list, msg) {
   } else {
     if (isDeep) {
       this.assert(
-        list.some(function(possibility) { return _.eql(expected, possibility) })
+        list.some(function(possibility) { return eql(expected, possibility) })
         , 'expected #{this} to deeply equal one of #{exp}'
         , 'expected #{this} to deeply equal one of #{exp}'
         , list

test/configuration.js

@@ -815,4 +815,23 @@ describe('configuration', function () {
       }
     });
   });
+
+  describe('deepEqual', function() {
+    it('should use custom deepEqual function for deepEqual comparison', function(){
+      chai.config.deepEqual = (expected, actual) => {
+        return chai.util.eql(expected, actual, {
+          comparator: (expected, actual) => {
+              // for non number comparison, use the default behavior
+              if(typeof expected !== 'number') return null;
+              // allow a difference of 10 between compared numbers
+              return typeof actual === 'number' && Math.abs(actual - expected) < 10
+          }
+        })
+      };
+      assert.deepEqual({v: 1}, {v: 10});
+      err(function() {
+        assert.deepEqual({v: 1}, {v: 100});
+      }, "expected { v: 1 } to deeply equal { v: 100 }");
+    })
+  })
 });