Dec 14, 2024 · Dec 7, 2024 · Dec 14, 2024
diff --git a/packages/eslint-plugin/src/rules/no-unnecessary-boolean-literal-compare.ts b/packages/eslint-plugin/src/rules/no-unnecessary-boolean-literal-compare.ts
 import * as tsutils from 'ts-api-utils';
 import * as ts from 'typescript';

 import { createRule, getParserServices, isStrongPrecedenceNode } from '../util';
 import {
  createRule,
  getConstrainedTypeAtLocation,
  getParserServices,
  isStrongPrecedenceNode,
 } from '../util';

 type MessageIds =
  | 'comparingNullableToFalse'
        return undefined;
      }

      const expressionType = services.getTypeAtLocation(comparison.expression);
      const expressionType = getConstrainedTypeAtLocation(
        services,
        comparison.expression,
      );

      if (isBooleanType(expressionType)) {
        return {
diff --git a/packages/eslint-plugin/tests/rules/no-unnecessary-boolean-literal-compare.test.ts b/packages/eslint-plugin/tests/rules/no-unnecessary-boolean-literal-compare.test.ts
      declare const varTrueOrStringOrUndefined: true | string | undefined;
      varTrueOrStringOrUndefined == true;
    `,
    `
      const test: <T>(someCondition: T) => void = someCondition => {
        if (someCondition === true) {
        }
      };
    `,
    `
      const test: <T>(someCondition: boolean | string) => void = someCondition => {
        if (someCondition === true) {
        }
      };
    `,
    `
      declare const varBooleanOrUndefined: boolean | undefined;
      varBooleanOrUndefined === true;
      `,
      options: [{ allowComparingNullableBooleansToTrue: false }],
    },
    {
      code: `
        const test: <T extends boolean | undefined>(
          someCondition: T,
        ) => void = someCondition => {
          if (someCondition === true) {
          }
        };
      `,
      options: [{ allowComparingNullableBooleansToFalse: false }],
    },
    {
      code: `
        const test: <T extends boolean | undefined>(
          someCondition: T,
        ) => void = someCondition => {
          if (someCondition === false) {
          }
        };
      `,
      options: [{ allowComparingNullableBooleansToTrue: false }],
    },
    "'false' === true;",
    "'true' === false;",
  ],
        }
      `,
    },
    {
      code: `
        const test: <T extends boolean>(someCondition: T) => void = someCondition => {
          if (someCondition === true) {
          }
        };
      `,
      errors: [
        {
          messageId: 'direct',
        },
      ],
      output: `
        const test: <T extends boolean>(someCondition: T) => void = someCondition => {
          if (someCondition) {
          }
        };
      `,
    },
    {
      code: `
        const test: <T extends boolean>(someCondition: T) => void = someCondition => {
          if (!(someCondition !== false)) {
          }
        };
      `,
      errors: [
        {
          messageId: 'negated',
        },
      ],
      output: `
        const test: <T extends boolean>(someCondition: T) => void = someCondition => {
          if (!someCondition) {
          }
        };
      `,
    },
    {
      code: `
        const test: <T extends boolean>(someCondition: T) => void = someCondition => {
          if (!((someCondition ?? true) !== false)) {
          }
        };
      `,
      errors: [
        {
          messageId: 'negated',
        },
      ],
      output: `
        const test: <T extends boolean>(someCondition: T) => void = someCondition => {
          if (!(someCondition ?? true)) {
          }
        };
      `,
    },
  ],
 });
Original file line number	Diff line number	Diff line change
Expand Up		@@ -4,7 +4,12 @@ import { AST_NODE_TYPES } from '@typescript-eslint/utils';
		import * as tsutils from 'ts-api-utils';
		import * as ts from 'typescript';

		import { createRule, getParserServices, isStrongPrecedenceNode } from '../util';
		import {
		createRule,
		getConstrainedTypeAtLocation,
		getParserServices,
		isStrongPrecedenceNode,
		} from '../util';

		type MessageIds =
		\| 'comparingNullableToFalse'
Expand DownExpand Up		@@ -89,7 +94,10 @@ export default createRule<Options, MessageIds>({
		return undefined;
		}

		const expressionType = services.getTypeAtLocation(comparison.expression);
		const expressionType = getConstrainedTypeAtLocation(
		services,
		comparison.expression,
		);

		if (isBooleanType(expressionType)) {
		return {
Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -55,6 +55,18 @@ ruleTester.run('no-unnecessary-boolean-literal-compare', rule, {
		declare const varTrueOrStringOrUndefined: true \| string \| undefined;
		varTrueOrStringOrUndefined == true;
		`,
		`
		const test: <T>(someCondition: T) => void = someCondition => {
		if (someCondition === true) {
		}
		};
		`,
		`
		const test: <T>(someCondition: boolean \| string) => void = someCondition => {
		if (someCondition === true) {
		}
		};
		`,
		`
		declare const varBooleanOrUndefined: boolean \| undefined;
		varBooleanOrUndefined === true;
Expand All		@@ -73,6 +85,28 @@ ruleTester.run('no-unnecessary-boolean-literal-compare', rule, {
		`,
		options: [{ allowComparingNullableBooleansToTrue: false }],
		},
		{
		code: `
		const test: <T extends boolean \| undefined>(
		someCondition: T,
		) => void = someCondition => {
		if (someCondition === true) {
		}
		};
		`,
		options: [{ allowComparingNullableBooleansToFalse: false }],
		},
		{
		code: `
		const test: <T extends boolean \| undefined>(
		someCondition: T,
		) => void = someCondition => {
		if (someCondition === false) {
		}
		};
		`,
		options: [{ allowComparingNullableBooleansToTrue: false }],
		},
		"'false' === true;",
		"'true' === false;",
		],
Expand DownExpand Up		@@ -481,5 +515,62 @@ ruleTester.run('no-unnecessary-boolean-literal-compare', rule, {
		}
		`,
		},
		{
		code: `
		const test: <T extends boolean>(someCondition: T) => void = someCondition => {
		if (someCondition === true) {
		}
		};
		`,
		errors: [
		{
		messageId: 'direct',
		},
		],
		output: `
		const test: <T extends boolean>(someCondition: T) => void = someCondition => {
		if (someCondition) {
		}
		};
		`,
		},
		{
		code: `
		const test: <T extends boolean>(someCondition: T) => void = someCondition => {
		if (!(someCondition !== false)) {
		}
		};
		`,
		errors: [
		{
		messageId: 'negated',
		},
		],
		output: `
		const test: <T extends boolean>(someCondition: T) => void = someCondition => {
		if (!someCondition) {
		}
		};
		`,
		},
		{
		code: `
		const test: <T extends boolean>(someCondition: T) => void = someCondition => {
		if (!((someCondition ?? true) !== false)) {
		}
		};
		`,
		errors: [
		{
		messageId: 'negated',
		},
		],
		output: `
		const test: <T extends boolean>(someCondition: T) => void = someCondition => {
		if (!(someCondition ?? true)) {
		}
		};
		`,
		},
		],
		});