From 624ac56606e0989c1a2202a02e652cf76df68ded Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jo=C3=A3o=20Dias=20Conde=20Azevedo?= <up201503256@fe.up.pt>
Date: Sun, 2 Dec 2018 00:35:42 +0000
Subject: [PATCH] Enhancement/expect-to-be-close-to-with-infinity (#7444)

* toBeCloseTo works properly when comparing with Infinity

* CHANGELOG update

* Linter issue solved

* Apply suggestions from code review

Co-Authored-By: joao-conde <up201503256@fe.up.pt>

* Update matchers.js

* Update CHANGELOG

* Fixed bug, leftover of old comment

* Removed unecessary self-explanatory comments

* Updated CHANGELOG

* Snapshot updates
---
 CHANGELOG.md                                  |  1 +
 .../__snapshots__/matchers.test.js.snap       | 40 +++++++++++++++++++
 .../expect/src/__tests__/matchers.test.js     | 22 ++++++++++
 packages/expect/src/matchers.js               |  8 +++-
 4 files changed, 70 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 64b83d253735..622c61c3e303 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -32,6 +32,7 @@
 - `[jest-config]` Add `dependencyExtractor` option to use a custom module to extract dependencies from files ([#7313](https://github.com/facebook/jest/pull/7313), [#7349](https://github.com/facebook/jest/pull/7349), [#7350](https://github.com/facebook/jest/pull/7350))
 - `[jest-haste-map]` Accept a `getCacheKey` method in `hasteImplModulePath` modules to reset the cache when the logic changes ([#7350](https://github.com/facebook/jest/pull/7350))
 - `[jest-config]` Add `haste.computeSha1` option to compute the sha-1 of the files in the haste map ([#7345](https://github.com/facebook/jest/pull/7345))
+- `[expect]` `expect(Infinity).toBeCloseTo(Infinity)` Treats `Infinity` as equal in toBeCloseTo matcher ([#7405](https://github.com/facebook/jest/pull/7405))
 
 ### Fixes
 
diff --git a/packages/expect/src/__tests__/__snapshots__/matchers.test.js.snap b/packages/expect/src/__tests__/__snapshots__/matchers.test.js.snap
index 6e9c035453aa..ad52eb43b2e1 100644
--- a/packages/expect/src/__tests__/__snapshots__/matchers.test.js.snap
+++ b/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>)</>
 
diff --git a/packages/expect/src/__tests__/matchers.test.js b/packages/expect/src/__tests__/matchers.test.js
index 83662ae03c41..6fa7323a1198 100644
--- a/packages/expect/src/__tests__/matchers.test.js
+++ b/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);
diff --git a/packages/expect/src/matchers.js b/packages/expect/src/matchers.js
index 13e516e48267..a7f987a9a85c 100644
--- a/packages/expect/src/matchers.js
+++ b/packages/expect/src/matchers.js
@@ -87,7 +87,13 @@ 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 (actual == Infinity && expected == Infinity) pass = true;
+    else if (actual == -Infinity && expected == -Infinity) pass = true;
+    else pass = Math.abs(expected - actual) < Math.pow(10, -precision) / 2;
+
     const message = () =>
       matcherHint('.toBeCloseTo', undefined, undefined, {
         isNot: this.isNot,