feat: support explicit comparisons to null for prefer-regexp-test (#839)

* feat: support explicit comparisons to null for prefer-regexp-test

* Create polite-berries-kiss.md

---------

Co-authored-by: Yosuke Ota <otameshiyo23@gmail.com>

Author: DMartens

.changeset/polite-berries-kiss.md

@@ -0,0 +1,5 @@
+---
+"eslint-plugin-regexp": minor
+---
+
+feat: support explicit comparisons to null for prefer-regexp-test

lib/rules/prefer-regexp-test.ts

@@ -1,3 +1,4 @@
+import type { SourceCode, Rule } from "eslint"
 import type * as ES from "estree"
 import { createRule } from "../utils"
 import {
@@ -95,10 +96,19 @@ export default createRule("prefer-regexp-test", {
                             const regexpText = sourceCode.text.slice(
                                 ...regexpRange,
                             )
+                            const convertedComparison =
+                                node.parent.type === "BinaryExpression" &&
+                                isComparisonToNull(node.parent)
+                                    ? convertComparison(
+                                          node.parent,
+                                          sourceCode,
+                                      )(fixer)
+                                    : [] // Do nothing
                             return [
                                 fixer.replaceTextRange(stringRange, regexpText),
                                 fixer.replaceText(memberExpr.property, "test"),
                                 fixer.replaceTextRange(regexpRange, stringText),
+                                ...convertedComparison,
                             ]
                         },
                     })
@@ -112,7 +122,19 @@ export default createRule("prefer-regexp-test", {
                         node: execNode,
                         messageId: "disallow",
                         data: { target: "RegExp#exec" },
-                        fix: (fixer) => fixer.replaceText(execNode, "test"),
+                        *fix(fixer) {
+                            yield fixer.replaceText(execNode, "test")
+
+                            if (
+                                node.parent.type === "BinaryExpression" &&
+                                isComparisonToNull(node.parent)
+                            ) {
+                                yield* convertComparison(
+                                    node.parent,
+                                    sourceCode,
+                                )(fixer)
+                            }
+                        },
                     })
                 }
             },
@@ -148,11 +170,46 @@ function isUseBoolean(node: ES.Expression): boolean {
         // e.g. if (expr) {}
         return parent.test === node
     }
+    if (parent.type === "BinaryExpression") {
+        // e.g. expr !== null
+        return isComparisonToNull(parent)
+    }
     if (parent.type === "LogicalExpression") {
         if (parent.operator === "&&" || parent.operator === "||") {
             // e.g. Boolean(expr1 || expr2)
             return isUseBoolean(parent)
         }
     }
+
     return false
 }
+
+function isComparisonToNull(binary: ES.BinaryExpression): boolean {
+    return (
+        (binary.operator === "===" || binary.operator === "!==") &&
+        binary.right.type === "Literal" &&
+        binary.right.value === null
+    )
+}
+
+function convertComparison(
+    comparison: ES.BinaryExpression,
+    sourceCode: SourceCode,
+): (fixer: Rule.RuleFixer) => Rule.Fix[] {
+    return function removeComparisonFixer(fixer: Rule.RuleFixer) {
+        const operator = sourceCode.getTokenBefore(
+            comparison.right,
+            ({ value }) => value === comparison.operator,
+        )!
+        const beforeOperator = sourceCode.getTokenBefore(operator, {
+            includeComments: true,
+        })!
+
+        return [
+            fixer.removeRange([beforeOperator.range![1], comparison.range![1]]),
+            ...(comparison.operator === "==="
+                ? [fixer.insertTextBefore(comparison.left, "!")]
+                : []),
+        ]
+    }
+}

lib/utils/ast-utils/utils.ts

@@ -222,6 +222,7 @@ export function findFunction(
 export type KnownMethodCall = CallExpression & {
     callee: MemberExpression & { object: Expression; property: Identifier }
     arguments: Expression[]
+    parent: Node
 }
 /**
  * Checks whether given node is expected method call

tests/lib/rules/__snapshots__/prefer-regexp-test.ts.eslintsnap

@@ -202,3 +202,67 @@ Output:
 [1] Use the `RegExp#test()` method instead of `RegExp#exec`, if you need a boolean.
 [2] Use the `RegExp#test()` method instead of `String#match`, if you need a boolean.
 ---
+
+
+Test: prefer-regexp-test >> invalid
+Code:
+  1 |
+  2 |         const text = 'something';
+  3 |         const pattern = /thing/;
+  4 |         const a = pattern.exec(test) === null;
+    |                           ^~~~ [1]
+  5 |         const b = pattern.exec(test) !== null;
+    |                           ^~~~ [2]
+  6 |         const c = text.match(pattern) === null;
+    |                   ^~~~~~~~~~~~~~~~~~~ [3]
+  7 |         const d = text.match(pattern) !== null;
+    |                   ^~~~~~~~~~~~~~~~~~~ [4]
+  8 |             
+
+Output:
+  1 |
+  2 |         const text = 'something';
+  3 |         const pattern = /thing/;
+  4 |         const a = !pattern.test(test);
+  5 |         const b = pattern.test(test);
+  6 |         const c = !pattern.test(text);
+  7 |         const d = pattern.test(text);
+  8 |             
+
+[1] Use the `RegExp#test()` method instead of `RegExp#exec`, if you need a boolean.
+[2] Use the `RegExp#test()` method instead of `RegExp#exec`, if you need a boolean.
+[3] Use the `RegExp#test()` method instead of `String#match`, if you need a boolean.
+[4] Use the `RegExp#test()` method instead of `String#match`, if you need a boolean.
+---
+
+
+Test: prefer-regexp-test >> invalid
+Code:
+  1 |
+  2 |         const text = 'something';
+  3 |         const pattern = /thing/;
+  4 |         const a = pattern.exec(test)=== null;
+    |                           ^~~~ [1]
+  5 |         const b = pattern.exec(test) /* Comment */ !== null;
+    |                           ^~~~ [2]
+  6 |         const c = text.match(pattern) === /** Comment */ null;
+    |                   ^~~~~~~~~~~~~~~~~~~ [3]
+  7 |         const d = (text.match(pattern)) !== null;
+    |                    ^~~~~~~~~~~~~~~~~~~ [4]
+  8 |             
+
+Output:
+  1 |
+  2 |         const text = 'something';
+  3 |         const pattern = /thing/;
+  4 |         const a = !pattern.test(test);
+  5 |         const b = pattern.test(test) /* Comment */;
+  6 |         const c = !pattern.test(text);
+  7 |         const d = (pattern.test(text));
+  8 |             
+
+[1] Use the `RegExp#test()` method instead of `RegExp#exec`, if you need a boolean.
+[2] Use the `RegExp#test()` method instead of `RegExp#exec`, if you need a boolean.
+[3] Use the `RegExp#test()` method instead of `String#match`, if you need a boolean.
+[4] Use the `RegExp#test()` method instead of `String#match`, if you need a boolean.
+---

tests/lib/rules/prefer-regexp-test.ts

@@ -38,6 +38,14 @@ tester.run("prefer-regexp-test", rule as any, {
         const pattern = /thin[[g]]/v;
         if (pattern.test(text)) {}
         `,
+        `
+        const text = 'something';
+        const pattern = /thing/;
+        const a = pattern.exec(test) instanceof null;
+        const b = pattern.exec(test) === maybeNull; 
+        const c = pattern.exec(test).groups !== undefined;
+        const d = text.match(pattern) != null;
+        `,
     ],
     invalid: [
         `
@@ -98,5 +106,21 @@ tester.run("prefer-regexp-test", rule as any, {
             if (pattern.exec(text)) {}
             if (text.match(pattern)) {}
             `,
+        `
+        const text = 'something';
+        const pattern = /thing/;
+        const a = pattern.exec(test) === null;
+        const b = pattern.exec(test) !== null;
+        const c = text.match(pattern) === null;
+        const d = text.match(pattern) !== null;
+            `,
+        `
+        const text = 'something';
+        const pattern = /thing/;
+        const a = pattern.exec(test)=== null;
+        const b = pattern.exec(test) /* Comment */ !== null;
+        const c = text.match(pattern) === /** Comment */ null;
+        const d = (text.match(pattern)) !== null;
+            `,
     ],
 })