feat(no-global-regexp-flag-in-query): Detect global RegExp in variable declarations (#678)

Closes #592

* fix: change function name to more informative and add JS Doc comment

* feat(no-global-regexp-flag-in-query): detect global regexp in variable declarations

Author: sjarva

lib/rules/no-global-regexp-flag-in-query.ts

@@ -37,7 +37,13 @@ export default createTestingLibraryRule<Options, MessageIds>({
 	},
 	defaultOptions: [],
 	create(context, _, helpers) {
-		function report(literalNode: TSESTree.Node) {
+		/**
+		 * Checks if node is reportable (has a regex that contains 'g') and if it is, reports it with `context.report()`.
+		 *
+		 * @param literalNode Literal node under to be
+		 * @returns {Boolean} indicatinf if literal was reported
+		 */
+		function reportLiteralWithRegex(literalNode: TSESTree.Node) {
 			if (
 				isLiteral(literalNode) &&
 				'regex' in literalNode &&
@@ -76,7 +82,37 @@ export default createTestingLibraryRule<Options, MessageIds>({
 			return [];
 		}
 
+		// Helper array to store variable nodes that have a literal with regex
+		// e.g. `const countRegExp = /count/gi` will be store here
+		const variableNodesWithRegexs: TSESTree.VariableDeclarator[] = [];
+
+		function hasRegexInVariable(
+			identifier: TSESTree.Identifier
+		): TSESTree.VariableDeclarator | undefined {
+			return variableNodesWithRegexs.find((varNode) => {
+				if (
+					ASTUtils.isVariableDeclarator(varNode) &&
+					ASTUtils.isIdentifier(varNode.id)
+				) {
+					return varNode.id.name === identifier.name;
+				}
+				return undefined;
+			});
+		}
+
 		return {
+			// internal helper function, helps store all variables with regex to `variableNodesWithRegexs`
+			// could potentially be refactored to using context.getDeclaredVariables()
+			VariableDeclarator(node: TSESTree.Node) {
+				if (
+					ASTUtils.isVariableDeclarator(node) &&
+					isLiteral(node.init) &&
+					'regex' in node.init &&
+					node.init.regex.flags.includes('g')
+				) {
+					variableNodesWithRegexs.push(node);
+				}
+			},
 			CallExpression(node) {
 				const identifierNode = getDeepestIdentifierNode(node);
 				if (!identifierNode || !helpers.isQuery(identifierNode)) {
@@ -85,11 +121,44 @@ export default createTestingLibraryRule<Options, MessageIds>({
 
 				const [firstArg, secondArg] = getArguments(identifierNode);
 
-				const firstArgumentHasError = report(firstArg);
+				const firstArgumentHasError = reportLiteralWithRegex(firstArg);
 				if (firstArgumentHasError) {
 					return;
 				}
 
+				// Case issue #592: a variable that has a regex is passed to testing library query
+
+				if (ASTUtils.isIdentifier(firstArg)) {
+					const regexVariableNode = hasRegexInVariable(firstArg);
+					if (regexVariableNode !== undefined) {
+						context.report({
+							node: firstArg,
+							messageId: 'noGlobalRegExpFlagInQuery',
+							fix(fixer) {
+								if (
+									ASTUtils.isVariableDeclarator(regexVariableNode) &&
+									isLiteral(regexVariableNode.init) &&
+									'regex' in regexVariableNode.init &&
+									regexVariableNode.init.regex.flags.includes('g')
+								) {
+									const splitter = regexVariableNode.init.raw.lastIndexOf('/');
+									const raw = regexVariableNode.init.raw.substring(0, splitter);
+									const flags = regexVariableNode.init.raw.substring(
+										splitter + 1
+									);
+									const flagsWithoutGlobal = flags.replace('g', '');
+
+									return fixer.replaceText(
+										regexVariableNode.init,
+										`${raw}/${flagsWithoutGlobal}`
+									);
+								}
+								return null;
+							},
+						});
+					}
+				}
+
 				if (isObjectExpression(secondArg)) {
 					const namePropertyNode = secondArg.properties.find(
 						(p) =>
@@ -100,7 +169,7 @@ export default createTestingLibraryRule<Options, MessageIds>({
 					) as TSESTree.Property | undefined;
 
 					if (namePropertyNode) {
-						report(namePropertyNode.value);
+						reportLiteralWithRegex(namePropertyNode.value);
 					}
 				}
 			},

tests/lib/rules/no-global-regexp-flag-in-query.test.ts

@@ -196,5 +196,29 @@ ruleTester.run(RULE_NAME, rule, {
         import { within } from '@testing-library/dom'
         within(element).queryAllByText(/hello/i)`,
 		},
+		{
+			code: `
+			const countRegExp = /count/gm
+			const anotherRegExp = /something/mgi
+			expect(screen.getByText(countRegExp)).toBeInTheDocument()
+			expect(screen.getByAllText(anotherRegExp)).toBeInTheDocument()`,
+			errors: [
+				{
+					messageId: 'noGlobalRegExpFlagInQuery',
+					line: 4,
+					column: 28,
+				},
+				{
+					messageId: 'noGlobalRegExpFlagInQuery',
+					line: 5,
+					column: 31,
+				},
+			],
+			output: `
+			const countRegExp = /count/m
+			const anotherRegExp = /something/mi
+			expect(screen.getByText(countRegExp)).toBeInTheDocument()
+			expect(screen.getByAllText(anotherRegExp)).toBeInTheDocument()`,
+		},
 	],
 });