From c5f75c47f3d56056c5e875d36b4e76f10ec063dd Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Kristj=C3=A1n=20Oddsson?= <koddsson@gmail.com>
Date: Wed, 22 Jan 2025 12:20:27 +0000
Subject: [PATCH] fix floating point precision in closeTo assertion

---
 lib/chai/core/assertions.js |  6 +++++-
 test/assert.js              |  4 ++++
 test/expect.js              |  6 ++++++
 test/should.js              | 10 ++++++++++
 4 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/lib/chai/core/assertions.js b/lib/chai/core/assertions.js
index 80a1ce7e..039c2654 100644
--- a/lib/chai/core/assertions.js
+++ b/lib/chai/core/assertions.js
@@ -3149,8 +3149,12 @@ function closeTo(expected, delta, msg) {
 
   const abs = (x) => (x < 0n ? -x : x);
 
+  // Used to round floating point number precision arithmetics
+  // See: https://stackoverflow.com/a/3644302
+  const strip = (number) => parseFloat(parseFloat(number).toPrecision(12));
+
   this.assert(
-    abs(obj - expected) <= delta,
+    strip(abs(obj - expected)) <= delta,
     'expected #{this} to be close to ' + expected + ' +/- ' + delta,
     'expected #{this} not to be close to ' + expected + ' +/- ' + delta
   );
diff --git a/test/assert.js b/test/assert.js
index 89395b05..d7934db7 100644
--- a/test/assert.js
+++ b/test/assert.js
@@ -1894,6 +1894,8 @@ describe('assert', function () {
     assert.closeTo(10, 20, 20);
     assert.closeTo(-10, 20, 30);
     assert.closeTo(10, 10, 0);
+    assert.closeTo(1682.6, 1682.7, 0.1);
+    assert.closeTo(1n, 2n, 1n);
 
     err(function(){
       assert.closeTo(2, 1.0, 0.5, 'blah');
@@ -1924,6 +1926,8 @@ describe('assert', function () {
     assert.approximately(1.5, 1.0, 0.5);
     assert.approximately(10, 20, 20);
     assert.approximately(-10, 20, 30);
+    assert.approximately(10, 10, 0);
+    assert.approximately(1682.6, 1682.7, 0.1);
     assert.approximately(1n, 2n, 1n);
 
     err(function(){
diff --git a/test/expect.js b/test/expect.js
index c9549d77..ed74a90f 100644
--- a/test/expect.js
+++ b/test/expect.js
@@ -3267,6 +3267,9 @@ describe('expect', function () {
     expect(1.5).to.be.closeTo(1.0, 0.5);
     expect(10).to.be.closeTo(20, 20);
     expect(-10).to.be.closeTo(20, 30);
+    expect(10).to.be.closeTo(10, 0);
+    expect(1682.6).to.be.closeTo(1682.7, 0.1);
+    expect(1n).to.be.closeTo(2n, 1n);
 
     err(function(){
       expect(2).to.be.closeTo(1.0, 0.5, 'blah');
@@ -3313,6 +3316,9 @@ describe('expect', function () {
     expect(1.5).to.be.approximately(1.0, 0.5);
     expect(10).to.be.approximately(20, 20);
     expect(-10).to.be.approximately(20, 30);
+    expect(10).to.be.approximately(10, 0);
+    expect(1682.6).to.be.approximately(1682.7, 0.1);
+    expect(1n).to.be.approximately(2n, 1n);
 
     err(function(){
       expect(2).to.be.approximately(1.0, 0.5, 'blah');
diff --git a/test/should.js b/test/should.js
index 4b7fbc48..5bae60dc 100644
--- a/test/should.js
+++ b/test/should.js
@@ -2749,6 +2749,11 @@ describe('should', function() {
 
   it('closeTo', function(){
     (1.5).should.be.closeTo(1.0, 0.5);
+    (10).should.be.closeTo(20, 20);
+    (-10).should.be.closeTo(20, 30);
+    (10).should.be.closeTo(10, 0);
+    (1682.6).should.be.closeTo(1682.7, 0.1);
+    (1n).should.be.closeTo(2n, 1n);
 
     err(function(){
       (2).should.be.closeTo(1.0, 0.5, 'blah');
@@ -2773,6 +2778,11 @@ describe('should', function() {
 
   it('approximately', function(){
     (1.5).should.be.approximately(1.0, 0.5);
+    (10).should.be.approximately(20, 20);
+    (-10).should.be.approximately(20, 30);
+    (10).should.be.approximately(10, 0);
+    (1682.6).should.be.approximately(1682.7, 0.1);
+    (1n).should.be.approximately(2n, 1n);
 
     err(function(){
       (2).should.be.approximately(1.0, 0.5, 'blah');