do not claim that -0 and 0 have no visual difference

Author: jeysal

CHANGELOG.md

@@ -50,6 +50,7 @@
 
 ### Fixes
 
+- `[jest-diff]` Do not claim that `-0` and `0` have no visual difference (TODO link)
 - `[expect]` `toStrictEqual` considers sparseness of arrays. ([#7591](https://github.com/facebook/jest/pull/7591))
 - `[jest-cli]` Fix empty coverage data for untested files ([#7388](https://github.com/facebook/jest/pull/7388))
 - `[jest-cli]` [**BREAKING**] Do not use `text-summary` coverage reporter by default if other reporters are configured ([#7058](https://github.com/facebook/jest/pull/7058))

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

@@ -360,11 +360,7 @@ exports[`.toBe() fails for: -0 and 0 1`] = `
 "<dim>expect(</><red>received</><dim>).toBe(</><green>expected</><dim>) // Object.is equality</>
 
 Expected: <green>0</>
-Received: <red>-0</>
-
-Difference:
-
-<dim>Compared values have no visual difference.</>"
+Received: <red>-0</>"
 `;
 
 exports[`.toBe() fails for: 1 and 2 1`] = `

packages/jest-diff/src/index.js

@@ -50,7 +50,7 @@ const FALLBACK_FORMAT_OPTIONS_0 = Object.assign({}, FALLBACK_FORMAT_OPTIONS, {
 // Generate a string that will highlight the difference between two values
 // with green and red. (similar to how github does code diffing)
 function diff(a: any, b: any, options: ?DiffOptions): ?string {
-  if (a === b) {
+  if (Object.is(a, b)) {
     return NO_DIFF_MESSAGE;
   }