Enhancement/expect-to-be-close-to-with-infinity

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ### Features
 
+- `[expect]` `expect(Infinity).toBeCloseTo(Infinity)` works as intended aswell as with `_Infinity` ([#7405](https://github.com/facebook/jest/pull/7405))
 - `[jest-cli]` [**BREAKING**] Only set error process error codes when they are non-zero ([#7363](https://github.com/facebook/jest/pull/7363))
 - `[jest-config]` [**BREAKING**] Deprecate `setupTestFrameworkScriptFile` in favor of new `setupFilesAfterEnv` ([#7119](https://github.com/facebook/jest/pull/7119))
 - `[jest-worker]` [**BREAKING**] Add functionality to call a `setup` method in the worker before the first call and a `teardown` method when ending the farm ([#7014](https://github.com/facebook/jest/pull/7014))

packages/expect/src/__tests__/__snapshots__/matchers.test.js.snap

@@ -368,6 +368,38 @@ Expected: <green>false</>
 Received: <red>true</>"
 `;
 
+exports[`.toBeCloseTo() {pass: false} expect(-Infinity)toBeCloseTo( -1.23) 1`] = `
+"<dim>expect(</><red>received</><dim>).toBeCloseTo(</><green>expected</><dim>)</>
+
+Precision: <green>2</>-digit
+Expected: <green>-1.23</>
+Received: <red>-Infinity</>"
+`;
+
+exports[`.toBeCloseTo() {pass: false} expect(Infinity)toBeCloseTo( -Infinity) 1`] = `
+"<dim>expect(</><red>received</><dim>).toBeCloseTo(</><green>expected</><dim>)</>
+
+Precision: <green>2</>-digit
+Expected: <green>-Infinity</>
+Received: <red>Infinity</>"
+`;
+
+exports[`.toBeCloseTo() {pass: false} expect(Infinity)toBeCloseTo( 1.23) 1`] = `
+"<dim>expect(</><red>received</><dim>).toBeCloseTo(</><green>expected</><dim>)</>
+
+Precision: <green>2</>-digit
+Expected: <green>1.23</>
+Received: <red>Infinity</>"
+`;
+
+exports[`.toBeCloseTo() {pass: true} expect(-Infinity)toBeCloseTo( -Infinity) 1`] = `
+"<dim>expect(</><red>received</><dim>).</>not<dim>.toBeCloseTo(</><green>expected</><dim>)</>
+
+Precision: <green>2</>-digit
+Expected: <green>-Infinity</>
+Received: <red>-Infinity</>"
+`;
+
 exports[`.toBeCloseTo() {pass: true} expect(0)toBeCloseTo( 0) 1`] = `
 "<dim>expect(</><red>received</><dim>).</>not<dim>.toBeCloseTo(</><green>expected</><dim>)</>
 
@@ -416,6 +448,14 @@ Expected: <green>1.234</>
 Received: <red>1.23</>"
 `;
 
+exports[`.toBeCloseTo() {pass: true} expect(Infinity)toBeCloseTo( Infinity) 1`] = `
+"<dim>expect(</><red>received</><dim>).</>not<dim>.toBeCloseTo(</><green>expected</><dim>)</>
+
+Precision: <green>2</>-digit
+Expected: <green>Infinity</>
+Received: <red>Infinity</>"
+`;
+
 exports[`.toBeCloseTo() accepts an optional precision argument: [0, 0.000004, 5] 1`] = `
 "<dim>expect(</><red>received</><dim>).</>not<dim>.toBeCloseTo(</><green>expected</><dim>, </><green>precision</><dim>)</>
 

packages/expect/src/__tests__/matchers.test.js

@@ -894,6 +894,28 @@ describe('.toBeCloseTo()', () => {
     });
   });
 
+  [[Infinity, Infinity], [-Infinity, -Infinity]].forEach(([n1, n2]) => {
+    it(`{pass: true} expect(${n1})toBeCloseTo( ${n2})`, () => {
+      jestExpect(n1).toBeCloseTo(n2);
+
+      expect(() =>
+        jestExpect(n1).not.toBeCloseTo(n2),
+      ).toThrowErrorMatchingSnapshot();
+    });
+  });
+
+  [[Infinity, -Infinity], [Infinity, 1.23], [-Infinity, -1.23]].forEach(
+    ([n1, n2]) => {
+      it(`{pass: false} expect(${n1})toBeCloseTo( ${n2})`, () => {
+        jestExpect(n1).not.toBeCloseTo(n2);
+
+        expect(() =>
+          jestExpect(n1).toBeCloseTo(n2),
+        ).toThrowErrorMatchingSnapshot();
+      });
+    },
+  );
+
   [[0, 0.1, 0], [0, 0.0001, 3], [0, 0.000004, 5]].forEach(([n1, n2, p]) => {
     it(`accepts an optional precision argument: [${n1}, ${n2}, ${p}]`, () => {
       jestExpect(n1).toBeCloseTo(n2, p);

packages/expect/src/matchers.js

@@ -87,7 +87,15 @@ const matchers: MatchersObject = {
   toBeCloseTo(actual: number, expected: number, precision?: number = 2) {
     const secondArgument = arguments.length === 3 ? 'precision' : null;
     ensureNumbers(actual, expected, '.toBeCloseTo');
-    const pass = Math.abs(expected - actual) < Math.pow(10, -precision) / 2;
+
+    let pass = false;
+    //If both actual and expected are Infinity it is true they are close
+    if (actual == Infinity && expected == Infinity) pass = true;
+    //If both actual and expected are -Infinity it is true they are close
+    else if (actual == -Infinity && expected == -Infinity) pass = true;
+    //actual and expected are close to each other taking precision into account
+    else pass = Math.abs(expected - actual) < Math.pow(10, -precision) / 2;
+
     const message = () =>
       matcherHint('.toBeCloseTo', undefined, undefined, {
         isNot: this.isNot,