Enhance Jest config error for setupTestFrameworkScriptFile (facebook#3512)

* Enhance Jest config error for `setupTestFrameworkScriptFile`

I wasn't aware of the fact that users of c-r-a could just define
`src/setupTests.js` and it would be configured with Jest - I nearly
ejected before I found a GitHub issue that confirmed this functionality.

I thought it might be a nice idea to add it to the error about Jest
config overrides to stop others ejecting when they don't need to.

* Change the order of Jest config errors.

* Show different error for `setupTestFrameworkScriptFile`

* Tweak the message

Author: jackfranklin

packages/react-scripts/scripts/utils/createJestConfig.js

@@ -75,25 +75,44 @@ module.exports = (resolve, rootDir, isEjecting) => {
     });
     const unsupportedKeys = Object.keys(overrides);
     if (unsupportedKeys.length) {
-      console.error(
-        chalk.red(
-          'Out of the box, Create React App only supports overriding ' +
-            'these Jest options:\n\n' +
-            supportedKeys.map(key => chalk.bold('  \u2022 ' + key)).join('\n') +
-            '.\n\n' +
-            'These options in your package.json Jest configuration ' +
-            'are not currently supported by Create React App:\n\n' +
-            unsupportedKeys
-              .map(key => chalk.bold('  \u2022 ' + key))
-              .join('\n') +
-            '\n\nIf you wish to override other Jest options, you need to ' +
-            'eject from the default setup. You can do so by running ' +
-            chalk.bold('npm run eject') +
-            ' but remember that this is a one-way operation. ' +
-            'You may also file an issue with Create React App to discuss ' +
-            'supporting more options out of the box.\n'
-        )
-      );
+      const isOverridingSetupFile =
+        unsupportedKeys.indexOf('setupTestFrameworkScriptFile') > -1;
+
+      if (isOverridingSetupFile) {
+        console.error(
+          chalk.red(
+            'We detected ' +
+              chalk.bold('setupTestFrameworkScriptFile') +
+              ' in your package.json.\n\n' +
+              'Remove it from Jest configuration, and put the initialization code in ' +
+              chalk.bold('src/setupTests.js') +
+              '.\nThis file will be loaded automatically.\n'
+          )
+        );
+      } else {
+        console.error(
+          chalk.red(
+            '\nOut of the box, Create React App only supports overriding ' +
+              'these Jest options:\n\n' +
+              supportedKeys
+                .map(key => chalk.bold('  \u2022 ' + key))
+                .join('\n') +
+              '.\n\n' +
+              'These options in your package.json Jest configuration ' +
+              'are not currently supported by Create React App:\n\n' +
+              unsupportedKeys
+                .map(key => chalk.bold('  \u2022 ' + key))
+                .join('\n') +
+              '\n\nIf you wish to override other Jest options, you need to ' +
+              'eject from the default setup. You can do so by running ' +
+              chalk.bold('npm run eject') +
+              ' but remember that this is a one-way operation. ' +
+              'You may also file an issue with Create React App to discuss ' +
+              'supporting more options out of the box.\n'
+          )
+        );
+      }
+
       process.exit(1);
     }
   }