fix(prefer-explicit-assert): check property existence (#476)

Author: Belco90

lib/rules/prefer-explicit-assert.ts

@@ -156,9 +156,17 @@ export default createTestingLibraryRule<Options, MessageIds>({
             const expectCallNode = findClosestCallNode(node, 'expect');
             if (!expectCallNode) return;
 
-            const expectStatement =
-              expectCallNode.parent as TSESTree.MemberExpression;
-            const property = expectStatement.property as TSESTree.Identifier;
+            const expectStatement = expectCallNode.parent;
+            if (!isMemberExpression(expectStatement)) {
+              return;
+            }
+
+            const property = expectStatement.property;
+
+            if (!ASTUtils.isIdentifier(property)) {
+              return;
+            }
+
             let matcher = property.name;
             let isNegatedMatcher = false;
 

package.json

@@ -45,6 +45,7 @@
     "@typescript-eslint/experimental-utils": "^4.30.0"
   },
   "devDependencies": {
+    "@babel/eslint-plugin": "^7.14.5",
     "@commitlint/cli": "^12.1.4",
     "@commitlint/config-conventional": "^12.1.4",
     "@types/jest": "^27.0.1",

tests/lib/rules/prefer-explicit-assert.test.ts

@@ -160,6 +160,19 @@ ruleTester.run(RULE_NAME, rule, {
         },
       ],
     })),
+    {
+      // https://github.com/testing-library/eslint-plugin-testing-library/issues/475
+      code: `
+    // incomplete expect statement should be ignored
+    expect('something');
+    expect(getByText('foo'));
+    `,
+      options: [
+        {
+          assertion: 'toBeInTheDocument',
+        },
+      ],
+    },
   ],
   invalid: [
     ...COMBINED_QUERIES_METHODS.map(