fix floating point precision in closeTo assertion (#1667)

chaijs · Feb 3, 2025 · 93409cd · 93409cd
1 parent 25bcaab
commit 93409cd
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Showing 4 changed files with 25 additions and 1 deletion.
diff --git a/lib/chai/core/assertions.js b/lib/chai/core/assertions.js
@@ -3150,8 +3150,12 @@ 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
@@ -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');
@@ -1928,6 +1930,8 @@ 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
@@ -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
@@ -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');