fix: support identifiers in to-be-undefined

Author: SimenB

rules/__tests__/prefer_to_be_null.test.js

@@ -6,7 +6,11 @@ const rules = require('../../').rules;
 const ruleTester = new RuleTester();
 
 ruleTester.run('prefer_to_be_null', rules['prefer-to-be-null'], {
-  valid: ['expect(null).toBeNull();', 'expect(null).toEqual();'],
+  valid: [
+    'expect(null).toBeNull();',
+    'expect(null).toEqual();',
+    "expect(something).toEqual('a string');",
+  ],
 
   invalid: [
     {

rules/__tests__/prefer_to_be_undefined.test.js

@@ -11,6 +11,10 @@ ruleTester.run('prefer_to_be_undefined', rules['prefer-to-be-undefined'], {
     'expect(true).not.toBeUndefined();',
     'expect({}).toEqual({});',
     'expect(null).toEqual(null);',
+    'expect(something).toBe(somethingElse)',
+    'expect(something).toEqual(somethingElse)',
+    'expect(something).not.toBe(somethingElse)',
+    'expect(something).not.toEqual(somethingElse)',
   ],
 
   invalid: [

rules/util.js

@@ -27,8 +27,10 @@ const expectToBeCase = (node, arg) =>
   expectCase(node) &&
   methodName(node) === 'toBe' &&
   argument(node) &&
-  argument(node).value === arg &&
-  (arg === null || argument(node).name);
+  ((argument(node).type === 'Literal' &&
+    argument(node).value === null &&
+    arg === null) ||
+    (argument(node).name === 'undefined' && arg === undefined));
 
 const expectNotToBeCase = (node, arg) =>
   expectNotCase(node) &&
@@ -42,8 +44,10 @@ const expectToEqualCase = (node, arg) =>
   expectCase(node) &&
   methodName(node) === 'toEqual' &&
   argument(node) &&
-  argument(node).value === arg &&
-  (arg === null || argument(node).name);
+  ((argument(node).type === 'Literal' &&
+    argument(node).value === null &&
+    arg === null) ||
+    (argument(node).name === 'undefined' && arg === undefined));
 
 const expectNotToEqualCase = (node, arg) =>
   expectNotCase(node) &&