From 8d6330cc04fcf0c214fe93bffb9caeedeea31a17 Mon Sep 17 00:00:00 2001
From: Nathan Landis <nathanlandis@gmail.com>
Date: Wed, 17 Apr 2019 16:31:57 -0500
Subject: [PATCH 1/2] Add delta message to closeTo() error

---
 chai.js                     | 3 ++-
 lib/chai/core/assertions.js | 3 ++-
 test/assert.js              | 8 ++++++++
 3 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/chai.js b/chai.js
index 39429c51b..f91d5b8f9 100644
--- a/chai.js
+++ b/chai.js
@@ -3311,8 +3311,9 @@ module.exports = function (chai, _) {
     new Assertion(obj, flagMsg, ssfi, true).is.a('number');
     if (typeof expected !== 'number' || typeof delta !== 'number') {
       flagMsg = flagMsg ? flagMsg + ': ' : '';
+      var deltaMessage = delta === undefined ? ", and a delta is required" : "";
       throw new AssertionError(
-          flagMsg + 'the arguments to closeTo or approximately must be numbers',
+          flagMsg + 'the arguments to closeTo or approximately must be numbers' + deltaMessage,
           undefined,
           ssfi
       );
diff --git a/lib/chai/core/assertions.js b/lib/chai/core/assertions.js
index cabcf622f..26404f5a8 100644
--- a/lib/chai/core/assertions.js
+++ b/lib/chai/core/assertions.js
@@ -2950,8 +2950,9 @@ module.exports = function (chai, _) {
     new Assertion(obj, flagMsg, ssfi, true).is.a('number');
     if (typeof expected !== 'number' || typeof delta !== 'number') {
       flagMsg = flagMsg ? flagMsg + ': ' : '';
+      var deltaMessage = delta === undefined ? ", and a delta is required" : "";
       throw new AssertionError(
-          flagMsg + 'the arguments to closeTo or approximately must be numbers',
+          flagMsg + 'the arguments to closeTo or approximately must be numbers' + deltaMessage,
           undefined,
           ssfi
       );
diff --git a/test/assert.js b/test/assert.js
index f9b3b1587..fd22d99cd 100644
--- a/test/assert.js
+++ b/test/assert.js
@@ -1848,6 +1848,10 @@ describe('assert', function () {
     err(function() {
       assert.closeTo(1.5, 1.0, true, 'blah');
     }, "blah: the arguments to closeTo or approximately must be numbers");
+
+    err(function() {
+      assert.closeTo(1.5, 1.0, undefined, 'blah');
+    }, "blah: the arguments to closeTo or approximately must be numbers, and a delta is required");
   });
 
   it('approximately', function(){
@@ -1874,6 +1878,10 @@ describe('assert', function () {
     err(function() {
       assert.approximately(1.5, 1.0, true, 'blah');
     }, "blah: the arguments to closeTo or approximately must be numbers");
+
+    err(function() {
+      assert.approximately(1.5, 1.0, undefined, 'blah');
+    }, "blah: the arguments to closeTo or approximately must be numbers, and a delta is required");
   });
 
   it('sameMembers', function() {

From 6bfd2fd131cb4e70e0dd81c3be5d7f8a677adc04 Mon Sep 17 00:00:00 2001
From: Nathan Landis <nathanlandis@gmail.com>
Date: Wed, 17 Apr 2019 16:44:03 -0500
Subject: [PATCH 2/2] Include some missed some test files

---
 test/expect.js | 8 ++++++++
 test/should.js | 8 ++++++++
 2 files changed, 16 insertions(+)

diff --git a/test/expect.js b/test/expect.js
index 9b4f485b8..6c87a8e84 100644
--- a/test/expect.js
+++ b/test/expect.js
@@ -3239,6 +3239,10 @@ describe('expect', function () {
     err(function() {
       expect(1.5, 'blah').to.be.closeTo(1.0, true);
     }, "blah: the arguments to closeTo or approximately must be numbers");
+
+    err(function() {
+      expect(1.5, 'blah').to.be.closeTo(1.0);
+    }, "blah: the arguments to closeTo or approximately must be numbers, and a delta is required");
   });
 
   it('approximately', function(){
@@ -3265,6 +3269,10 @@ describe('expect', function () {
     err(function() {
       expect(1.5).to.be.approximately(1.0, true);
     }, "the arguments to closeTo or approximately must be numbers");
+
+    err(function() {
+      expect(1.5).to.be.approximately(1.0);
+    }, "the arguments to closeTo or approximately must be numbers, and a delta is required");
   });
 
   it('oneOf', function() {
diff --git a/test/should.js b/test/should.js
index 9a2400dfb..b7e1d2728 100644
--- a/test/should.js
+++ b/test/should.js
@@ -2796,6 +2796,10 @@ describe('should', function() {
     err(function() {
       (1.5).should.be.closeTo(1.0, true, 'blah');
     }, "blah: the arguments to closeTo or approximately must be numbers");
+
+    err(function() {
+      (1.5).should.be.closeTo(1.0, undefined, 'blah');
+    }, "blah: the arguments to closeTo or approximately must be numbers, and a delta is required");
   });
 
   it('approximately', function(){
@@ -2816,6 +2820,10 @@ describe('should', function() {
     err(function() {
       (1.5).should.be.approximately(1.0, true);
     }, "the arguments to closeTo or approximately must be numbers");
+
+    err(function() {
+      (1.5).should.be.approximately(1.0);
+    }, "the arguments to closeTo or approximately must be numbers, and a delta is required");
   });
 
   it('include.members', function() {