JS-1993 S5906: clarify that length matchers apply beyond collections (#7434)

Author: nathsou

packages/analysis/src/jsts/rules/S5906/assertion-suggestions.ts

@@ -229,22 +229,36 @@ function buildLengthEqualitySuggestion(
   const actual = sourceCode.getText(actualNode);
   if (family === 'jest' || family === 'jasmine') {
     const matcher = family === 'jasmine' ? 'toHaveSize' : 'toHaveLength';
-    return replacement(`expect(${actual})${negation(same)}.${matcher}(${expected})`, node);
+    return replacement(
+      `expect(${actual})${negation(same)}.${matcher}(${expected})`,
+      node,
+      undefined,
+      'preferSpecificLengthAssertion',
+    );
   }
   if (family === 'assert') {
     return same
-      ? replacement(`${assertObject}.lengthOf(${actual}, ${expected}${extraArguments})`, node)
+      ? replacement(
+          `${assertObject}.lengthOf(${actual}, ${expected}${extraArguments})`,
+          node,
+          undefined,
+          'preferSpecificLengthAssertion',
+        )
       : null;
   }
   if (family === 'chai-should') {
     return replacement(
       `${chaiShouldReceiver(actual, actualNode)}.should${negation(same)}.have.lengthOf(${expected})`,
       node,
+      undefined,
+      'preferSpecificLengthAssertion',
     );
   }
   return replacement(
     `expect(${actual}${extraArguments}).to${negation(same)}.have.lengthOf(${expected})`,
     node,
+    undefined,
+    'preferSpecificLengthAssertion',
   );
 }
 

packages/analysis/src/jsts/rules/S5906/assertion-utils.ts

@@ -22,6 +22,7 @@ import { getVariableFromName, isIdentifier, isMethodCall } from '../helpers/ast.
 export type Suggestion = {
   assertion: string;
   replacement?: string;
+  messageId?: 'preferSpecificAssertion' | 'preferSpecificLengthAssertion';
 };
 
 const PLAYWRIGHT_LOCATOR_FACTORIES = new Set([
@@ -124,9 +125,11 @@ export function replacement(
   replacementText: string,
   _node: estree.CallExpression,
   _sourceCode?: SourceCode,
+  messageId?: Suggestion['messageId'],
 ): Suggestion {
   return {
     assertion: replacementText,
     replacement: replacementText,
+    ...(messageId ? { messageId } : {}),
   };
 }

packages/analysis/src/jsts/rules/S5906/chai-bdd.unit.test.ts

@@ -25,6 +25,10 @@ describe('S5906', () => {
       messageId: 'preferSpecificAssertion',
       suggestions: [{ messageId: 'quickfix', output }],
     });
+    const expectedLengthError = (output: string) => ({
+      messageId: 'preferSpecificLengthAssertion',
+      suggestions: [{ messageId: 'quickfix', output }],
+    });
 
     ruleTester.run('prefer-specific-assertions', rule, {
       valid: [],
@@ -106,7 +110,7 @@ describe('S5906', () => {
             expect(items.length).to.equal(2);
           `,
           errors: [
-            expectedError(`
+            expectedLengthError(`
             import { expect } from 'chai';
 
             expect(items).to.have.lengthOf(2);

packages/analysis/src/jsts/rules/S5906/integrations.unit.test.ts

@@ -25,6 +25,10 @@ describe('S5906', () => {
       messageId: 'preferSpecificAssertion',
       suggestions: [{ messageId: 'quickfix', output }],
     });
+    const expectedLengthError = (output: string) => ({
+      messageId: 'preferSpecificLengthAssertion',
+      suggestions: [{ messageId: 'quickfix', output }],
+    });
     const expectedErrorWithoutSuggestion = {
       messageId: 'preferSpecificAssertion',
       suggestions: [],
@@ -191,7 +195,7 @@ describe('S5906', () => {
             assert.strictEqual(items.length, 2, 'item count');
           `,
           errors: [
-            expectedError(`
+            expectedLengthError(`
             import { assert } from 'chai';
 
             assert.lengthOf(items, 2, 'item count');

packages/analysis/src/jsts/rules/S5906/rule.ts

@@ -46,7 +46,9 @@ import { getPlaywrightLocatorSuggestion } from './playwright-suggestions.js';
 
 const messages = {
   preferSpecificAssertion:
-    'Prefer a more specific assertion instead of this generic one, e.g. "{{assertion}}".',
+    'Prefer "{{assertion}}" over this generic assertion; dedicated matchers read better and report clearer failures.',
+  preferSpecificLengthAssertion:
+    'Prefer "{{assertion}}" over this generic assertion for better reporting; it works on any object with a numeric length property.',
   quickfix: 'Replace with {{assertion}}.',
 };
 
@@ -83,7 +85,7 @@ export const rule: Rule.RuleModule = {
 
       context.report({
         node: node.callee,
-        messageId: 'preferSpecificAssertion',
+        messageId: suggestion.messageId ?? 'preferSpecificAssertion',
         data: { assertion: suggestion.assertion },
         ...(suggest ? { suggest } : {}),
       });
@@ -210,6 +212,7 @@ function getExpectLikeSuggestion(
       `expect(${sourceCode.getText(actual.object)}).${negated ? 'not.' : ''}${lengthMatcher}(${expectedText})`,
       node,
       sourceCode,
+      'preferSpecificLengthAssertion',
     );
   }
   const booleanExpected = getBooleanValue(expected);
@@ -370,6 +373,7 @@ function getChaiAssertSuggestion(
       `${assertText}.lengthOf(${sourceCode.getText(actual.object)}, ${sourceCode.getText(expected)}${trailingArgs})`,
       node,
       sourceCode,
+      'preferSpecificLengthAssertion',
     );
   }
   const booleanExpected = getBooleanValue(expected);
@@ -415,6 +419,7 @@ function getChaiValueSuggestion(
       `expect(${sourceCode.getText(actual.object)}${messageArguments}).to${negated ? '.not' : ''}.have.lengthOf(${sourceCode.getText(expected)})`,
       node,
       sourceCode,
+      'preferSpecificLengthAssertion',
     );
   }
   const booleanExpected = getBooleanValue(expected);
@@ -460,6 +465,7 @@ function getChaiShouldValueSuggestion(
       `${receiver}.should${negated ? '.not' : ''}.have.lengthOf(${sourceCode.getText(expected)})`,
       node,
       sourceCode,
+      'preferSpecificLengthAssertion',
     );
   }
   const booleanExpected = getBooleanValue(expected);

packages/analysis/src/jsts/rules/S5906/unit.test.ts

@@ -44,6 +44,10 @@ describe('S5906', () => {
       messageId: 'preferSpecificAssertion',
       suggestions: [{ messageId: 'quickfix', output }],
     });
+    const expectedLengthError = (output: string) => ({
+      messageId: 'preferSpecificLengthAssertion',
+      suggestions: [{ messageId: 'quickfix', output }],
+    });
 
     ruleTester.run('prefer-specific-assertions', rule, {
       valid: [
@@ -184,7 +188,7 @@ describe('S5906', () => {
           `,
           filename: modernJasmineFixture,
           errors: [
-            expectedError(`
+            expectedLengthError(`
             import { expect } from 'jasmine';
 
             expect(items).toHaveSize(3);
@@ -199,7 +203,7 @@ describe('S5906', () => {
           `,
           filename: mixedJasmineJestFixture,
           errors: [
-            expectedError(`
+            expectedLengthError(`
             import { expect } from 'jasmine';
 
             expect(items).toHaveSize(3);
@@ -237,7 +241,7 @@ describe('S5906', () => {
             });
           `,
           errors: [
-            expectedError(`
+            expectedLengthError(`
             import { expect, test } from 'vitest';
 
             test('uses generic length assertion', () => {
@@ -254,7 +258,7 @@ describe('S5906', () => {
           `,
           filename: mixedJasmineJestFixture,
           errors: [
-            expectedError(`
+            expectedLengthError(`
             import { expect } from 'vitest';
 
             expect(items).toHaveLength(3);
@@ -338,7 +342,7 @@ describe('S5906', () => {
             expect(items.length === 2).toBe(true);
           `,
           errors: [
-            expectedError(`
+            expectedLengthError(`
             import { expect } from 'vitest';
 
             expect(items).toHaveLength(2);
@@ -352,7 +356,7 @@ describe('S5906', () => {
             expect(items.length === 2).toBe(true);
           `,
           errors: [
-            expectedError(`
+            expectedLengthError(`
             import { expect } from 'jasmine';
 
             expect(items).toHaveSize(2);