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strict-boolean-expressions.test.ts
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strict-boolean-expressions.test.ts
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import * as path from 'path';
import type {
MessageId,
Options,
} from '../../src/rules/strict-boolean-expressions';
import rule from '../../src/rules/strict-boolean-expressions';
import {
batchedSingleLineTests,
getFixturesRootDir,
noFormat,
RuleTester,
} from '../RuleTester';
const rootPath = getFixturesRootDir();
const ruleTester = new RuleTester({
parser: '@typescript-eslint/parser',
parserOptions: {
tsconfigRootDir: rootPath,
project: './tsconfig.json',
},
});
ruleTester.run('strict-boolean-expressions', rule, {
valid: [
// boolean in boolean context
...batchedSingleLineTests<Options>({
code: noFormat`
true ? "a" : "b";
if (false) {}
while (true) {}
for (; false;) {}
!true;
false || 123;
true && "foo";
!(false || true);
true && false ? true : false;
false && true || false;
false && true || [];
(false && 1) || (true && 2);
declare const x: boolean; if (x) {}
(x: boolean) => !x;
<T extends boolean>(x: T) => x ? 1 : 0;
declare const x: never; if (x) {}
`,
}),
// string in boolean context
...batchedSingleLineTests<Options>({
code: noFormat`
if ("") {}
while ("x") {}
for (; "";) {}
"" && "1" || x;
declare const x: string; if (x) {}
(x: string) => !x;
<T extends string>(x: T) => x ? 1 : 0;
`,
}),
// number in boolean context
...batchedSingleLineTests<Options>({
code: noFormat`
if (0) {}
while (1n) {}
for (; Infinity;) {}
0 / 0 && 1 + 2 || x;
declare const x: number; if (x) {}
(x: bigint) => !x;
<T extends number>(x: T) => x ? 1 : 0;
`,
}),
// nullable object in boolean context
...batchedSingleLineTests<Options>({
code: noFormat`
declare const x: null | object; if (x) {}
(x?: { a: any }) => !x;
<T extends {} | null | undefined>(x: T) => x ? 1 : 0;
`,
}),
// nullable boolean in boolean context
...batchedSingleLineTests<Options>({
options: [{ allowNullableBoolean: true }],
code: noFormat`
declare const x: boolean | null; if (x) {}
(x?: boolean) => !x;
<T extends boolean | null | undefined>(x: T) => x ? 1 : 0;
`,
}),
// nullable string in boolean context
...batchedSingleLineTests<Options>({
options: [{ allowNullableString: true }],
code: noFormat`
declare const x: string | null; if (x) {}
(x?: string) => !x;
<T extends string | null | undefined>(x: T) => x ? 1 : 0;
`,
}),
// nullable number in boolean context
...batchedSingleLineTests<Options>({
options: [{ allowNullableNumber: true }],
code: noFormat`
declare const x: number | null; if (x) {}
(x?: number) => !x;
<T extends number | null | undefined>(x: T) => x ? 1 : 0;
`,
}),
// any in boolean context
...batchedSingleLineTests<Options>({
options: [{ allowAny: true }],
code: noFormat`
declare const x: any; if (x) {}
(x) => !x;
<T extends any>(x: T) => x ? 1 : 0;
`,
}),
// logical operator
...batchedSingleLineTests<Options>({
options: [{ allowString: true, allowNumber: true }],
code: `
1 && true && 'x' && {};
let x = 0 || false || '' || null;
if (1 && true && 'x') void 0;
if (0 || false || '') void 0;
1 && true && 'x' ? {} : null;
0 || false || '' ? null : {};
`,
}),
// nullable enum in boolean context
{
code: `
enum ExampleEnum {
This = 0,
That = 1,
}
const rand = Math.random();
let theEnum: ExampleEnum | null = null;
if (rand < 0.3) {
theEnum = ExampleEnum.This;
}
if (theEnum) {
}
`,
options: [{ allowNullableEnum: true }],
},
{
code: `
enum ExampleEnum {
This = 0,
That = 1,
}
const rand = Math.random();
let theEnum: ExampleEnum | null = null;
if (rand < 0.3) {
theEnum = ExampleEnum.This;
}
if (!theEnum) {
}
`,
options: [{ allowNullableEnum: true }],
},
{
code: `
enum ExampleEnum {
This = 1,
That = 2,
}
const rand = Math.random();
let theEnum: ExampleEnum | null = null;
if (rand < 0.3) {
theEnum = ExampleEnum.This;
}
if (!theEnum) {
}
`,
options: [{ allowNullableEnum: true }],
},
{
code: `
enum ExampleEnum {
This = 'one',
That = 'two',
}
const rand = Math.random();
let theEnum: ExampleEnum | null = null;
if (rand < 0.3) {
theEnum = ExampleEnum.This;
}
if (!theEnum) {
}
`,
options: [{ allowNullableEnum: true }],
},
{
code: `
declare const x: string[] | null;
// eslint-disable-next-line
if (x) {
}
`,
options: [
{
allowRuleToRunWithoutStrictNullChecksIKnowWhatIAmDoing: true,
},
],
parserOptions: {
tsconfigRootDir: path.join(rootPath, 'unstrict'),
},
},
`
function f(arg: 'a' | null) {
if (arg) console.log(arg);
}
`,
`
function f(arg: 'a' | 'b' | null) {
if (arg) console.log(arg);
}
`,
{
code: `
declare const x: 1 | null;
declare const y: 1;
if (x) {
}
if (y) {
}
`,
options: [
{
allowNumber: true,
},
],
},
`
function f(arg: 1 | null) {
if (arg) console.log(arg);
}
`,
`
function f(arg: 1 | 2 | null) {
if (arg) console.log(arg);
}
`,
`
interface Options {
readonly enableSomething?: true;
}
function f(opts: Options): void {
if (opts.enableSomething) console.log('Do something');
}
`,
`
declare const x: true | null;
if (x) {
}
`,
{
code: `
declare const x: 'a' | null;
declare const y: 'a';
if (x) {
}
if (y) {
}
`,
options: [
{
allowString: true,
},
],
},
],
invalid: [
// non-boolean in RHS of test expression
...batchedSingleLineTests<MessageId, Options>({
options: [
{ allowString: false, allowNumber: false, allowNullableObject: false },
],
code: noFormat`
if (true && (1 + 1)) {}
while (false || "a" + "b") {}
(x: object) => true || false || x ? true : false;
`,
errors: [
{
messageId: 'conditionErrorNumber',
line: 2,
column: 14,
suggestions: [
{
messageId: 'conditionFixCompareZero',
output: 'if (true && ((1 + 1) !== 0)) {}',
},
{
messageId: 'conditionFixCompareNaN',
output: 'if (true && (!Number.isNaN((1 + 1)))) {}',
},
{
messageId: 'conditionFixCastBoolean',
output: 'if (true && (Boolean((1 + 1)))) {}',
},
],
},
{
messageId: 'conditionErrorString',
line: 3,
column: 25,
suggestions: [
{
messageId: 'conditionFixCompareStringLength',
output: ' while (false || (("a" + "b").length > 0)) {}',
},
{
messageId: 'conditionFixCompareEmptyString',
output: ' while (false || (("a" + "b") !== "")) {}',
},
{
messageId: 'conditionFixCastBoolean',
output: ' while (false || (Boolean(("a" + "b")))) {}',
},
],
},
{ messageId: 'conditionErrorObject', line: 4, column: 41 },
],
}),
// check if all and only the outermost operands are checked
{
options: [
{ allowString: false, allowNumber: false, allowNullableObject: false },
],
code: noFormat`if (('' && {}) || (0 && void 0)) { }`,
errors: [
{
messageId: 'conditionErrorString',
line: 1,
column: 6,
suggestions: [
{
messageId: 'conditionFixCompareStringLength',
output: `if (((''.length > 0) && {}) || (0 && void 0)) { }`,
},
{
messageId: 'conditionFixCompareEmptyString',
output: `if ((('' !== "") && {}) || (0 && void 0)) { }`,
},
{
messageId: 'conditionFixCastBoolean',
output: `if (((Boolean('')) && {}) || (0 && void 0)) { }`,
},
],
},
{ messageId: 'conditionErrorObject', line: 1, column: 12 },
{
messageId: 'conditionErrorNumber',
line: 1,
column: 20,
suggestions: [
{
messageId: 'conditionFixCompareZero',
output: `if (('' && {}) || ((0 !== 0) && void 0)) { }`,
},
{
messageId: 'conditionFixCompareNaN',
output: `if (('' && {}) || ((!Number.isNaN(0)) && void 0)) { }`,
},
{
messageId: 'conditionFixCastBoolean',
output: `if (('' && {}) || ((Boolean(0)) && void 0)) { }`,
},
],
},
{ messageId: 'conditionErrorNullish', line: 1, column: 25 },
],
},
// shouldn't check last logical operand when used for control flow
{
options: [{ allowString: false, allowNumber: false }],
code: "'asd' && 123 && [] && null;",
errors: [
{ messageId: 'conditionErrorString', line: 1, column: 1 },
{ messageId: 'conditionErrorNumber', line: 1, column: 10 },
{ messageId: 'conditionErrorObject', line: 1, column: 17 },
],
},
{
options: [{ allowString: false, allowNumber: false }],
code: "'asd' || 123 || [] || null;",
errors: [
{ messageId: 'conditionErrorString', line: 1, column: 1 },
{ messageId: 'conditionErrorNumber', line: 1, column: 10 },
{ messageId: 'conditionErrorObject', line: 1, column: 17 },
],
},
{
options: [{ allowString: false, allowNumber: false }],
code: "let x = (1 && 'a' && null) || 0 || '' || {};",
errors: [
{ messageId: 'conditionErrorNumber', line: 1, column: 10 },
{ messageId: 'conditionErrorString', line: 1, column: 15 },
{ messageId: 'conditionErrorNullish', line: 1, column: 22 },
{ messageId: 'conditionErrorNumber', line: 1, column: 31 },
{ messageId: 'conditionErrorString', line: 1, column: 36 },
],
},
{
options: [{ allowString: false, allowNumber: false }],
code: "return (1 || 'a' || null) && 0 && '' && {};",
errors: [
{ messageId: 'conditionErrorNumber', line: 1, column: 9 },
{ messageId: 'conditionErrorString', line: 1, column: 14 },
{ messageId: 'conditionErrorNullish', line: 1, column: 21 },
{ messageId: 'conditionErrorNumber', line: 1, column: 30 },
{ messageId: 'conditionErrorString', line: 1, column: 35 },
],
},
{
options: [{ allowString: false, allowNumber: false }],
code: "console.log((1 && []) || ('a' && {}));",
errors: [
{ messageId: 'conditionErrorNumber', line: 1, column: 14 },
{ messageId: 'conditionErrorObject', line: 1, column: 19 },
{ messageId: 'conditionErrorString', line: 1, column: 27 },
],
},
// should check all logical operands when used in a condition
{
options: [{ allowString: false, allowNumber: false }],
code: "if ((1 && []) || ('a' && {})) void 0;",
errors: [
{ messageId: 'conditionErrorNumber', line: 1, column: 6 },
{ messageId: 'conditionErrorObject', line: 1, column: 11 },
{ messageId: 'conditionErrorString', line: 1, column: 19 },
{ messageId: 'conditionErrorObject', line: 1, column: 26 },
],
},
{
options: [{ allowString: false, allowNumber: false }],
code: "let x = null || 0 || 'a' || [] ? {} : undefined;",
errors: [
{ messageId: 'conditionErrorNullish', line: 1, column: 9 },
{ messageId: 'conditionErrorNumber', line: 1, column: 17 },
{ messageId: 'conditionErrorString', line: 1, column: 22 },
{ messageId: 'conditionErrorObject', line: 1, column: 29 },
],
},
{
options: [{ allowString: false, allowNumber: false }],
code: "return !(null || 0 || 'a' || []);",
errors: [
{ messageId: 'conditionErrorNullish', line: 1, column: 10 },
{ messageId: 'conditionErrorNumber', line: 1, column: 18 },
{ messageId: 'conditionErrorString', line: 1, column: 23 },
{ messageId: 'conditionErrorObject', line: 1, column: 30 },
],
},
// nullish in boolean context
...batchedSingleLineTests<MessageId, Options>({
code: noFormat`
null || {};
undefined && [];
declare const x: null; if (x) {}
(x: undefined) => !x;
<T extends null | undefined>(x: T) => x ? 1 : 0;
<T extends null>(x: T) => x ? 1 : 0;
<T extends undefined>(x: T) => x ? 1 : 0;
`,
errors: [
{ messageId: 'conditionErrorNullish', line: 2, column: 1 },
{ messageId: 'conditionErrorNullish', line: 3, column: 9 },
{ messageId: 'conditionErrorNullish', line: 4, column: 36 },
{ messageId: 'conditionErrorNullish', line: 5, column: 28 },
{ messageId: 'conditionErrorNullish', line: 6, column: 47 },
{ messageId: 'conditionErrorNullish', line: 7, column: 35 },
{ messageId: 'conditionErrorNullish', line: 8, column: 40 },
],
}),
// object in boolean context
...batchedSingleLineTests<MessageId, Options>({
code: noFormat`
[] || 1;
({}) && "a";
declare const x: symbol; if (x) {}
(x: () => void) => !x;
<T extends object>(x: T) => x ? 1 : 0;
<T extends Object | Function>(x: T) => x ? 1 : 0;
<T extends { a: number }>(x: T) => x ? 1 : 0;
<T extends () => void>(x: T) => x ? 1 : 0;
`,
errors: [
{ messageId: 'conditionErrorObject', line: 2, column: 1 },
{ messageId: 'conditionErrorObject', line: 3, column: 10 },
{ messageId: 'conditionErrorObject', line: 4, column: 38 },
{ messageId: 'conditionErrorObject', line: 5, column: 29 },
{ messageId: 'conditionErrorObject', line: 6, column: 37 },
{ messageId: 'conditionErrorObject', line: 7, column: 48 },
{ messageId: 'conditionErrorObject', line: 8, column: 44 },
{ messageId: 'conditionErrorObject', line: 9, column: 41 },
],
}),
// string in boolean context
...batchedSingleLineTests<MessageId, Options>({
options: [{ allowString: false }],
code: noFormat`
while ("") {}
for (; "foo";) {}
declare const x: string; if (x) {}
(x: string) => (!x);
<T extends string>(x: T) => x ? 1 : 0;
`,
errors: [
{
messageId: 'conditionErrorString',
line: 2,
column: 8,
suggestions: [
{
messageId: 'conditionFixCompareStringLength',
output: `while ("".length > 0) {}`,
},
{
messageId: 'conditionFixCompareEmptyString',
output: `while ("" !== "") {}`,
},
{
messageId: 'conditionFixCastBoolean',
output: `while (Boolean("")) {}`,
},
],
},
{
messageId: 'conditionErrorString',
line: 3,
column: 16,
suggestions: [
{
messageId: 'conditionFixCompareStringLength',
output: ` for (; "foo".length > 0;) {}`,
},
{
messageId: 'conditionFixCompareEmptyString',
output: ` for (; "foo" !== "";) {}`,
},
{
messageId: 'conditionFixCastBoolean',
output: ` for (; Boolean("foo");) {}`,
},
],
},
{
messageId: 'conditionErrorString',
line: 4,
column: 38,
suggestions: [
{
messageId: 'conditionFixCompareStringLength',
output: ` declare const x: string; if (x.length > 0) {}`,
},
{
messageId: 'conditionFixCompareEmptyString',
output: ` declare const x: string; if (x !== "") {}`,
},
{
messageId: 'conditionFixCastBoolean',
output: ` declare const x: string; if (Boolean(x)) {}`,
},
],
},
{
messageId: 'conditionErrorString',
line: 5,
column: 26,
suggestions: [
{
messageId: 'conditionFixCompareStringLength',
output: ` (x: string) => (x.length === 0);`,
},
{
messageId: 'conditionFixCompareEmptyString',
output: ` (x: string) => (x === "");`,
},
{
messageId: 'conditionFixCastBoolean',
output: ` (x: string) => (!Boolean(x));`,
},
],
},
{
messageId: 'conditionErrorString',
line: 6,
column: 37,
suggestions: [
{
messageId: 'conditionFixCompareStringLength',
output: ` <T extends string>(x: T) => (x.length > 0) ? 1 : 0;`,
},
{
messageId: 'conditionFixCompareEmptyString',
output: ` <T extends string>(x: T) => (x !== "") ? 1 : 0;`,
},
{
messageId: 'conditionFixCastBoolean',
output: ` <T extends string>(x: T) => (Boolean(x)) ? 1 : 0;`,
},
],
},
],
}),
// number in boolean context
...batchedSingleLineTests<MessageId, Options>({
options: [{ allowNumber: false }],
code: noFormat`
while (0n) {}
for (; 123;) {}
declare const x: number; if (x) {}
(x: bigint) => !x;
<T extends number>(x: T) => (x) ? 1 : 0;
![]["length"]; // doesn't count as array.length when computed
declare const a: any[] & { notLength: number }; if (a.notLength) {}
`,
errors: [
{
messageId: 'conditionErrorNumber',
line: 2,
column: 8,
suggestions: [
{
messageId: 'conditionFixCompareZero',
// TODO: fix compare zero suggestion for bigint
output: `while (0n !== 0) {}`,
},
{
// TODO: remove check NaN suggestion for bigint
messageId: 'conditionFixCompareNaN',
output: `while (!Number.isNaN(0n)) {}`,
},
{
messageId: 'conditionFixCastBoolean',
output: `while (Boolean(0n)) {}`,
},
],
},
{
messageId: 'conditionErrorNumber',
line: 3,
column: 16,
suggestions: [
{
messageId: 'conditionFixCompareZero',
output: ` for (; 123 !== 0;) {}`,
},
{
messageId: 'conditionFixCompareNaN',
output: ` for (; !Number.isNaN(123);) {}`,
},
{
messageId: 'conditionFixCastBoolean',
output: ` for (; Boolean(123);) {}`,
},
],
},
{
messageId: 'conditionErrorNumber',
line: 4,
column: 38,
suggestions: [
{
messageId: 'conditionFixCompareZero',
output: ` declare const x: number; if (x !== 0) {}`,
},
{
messageId: 'conditionFixCompareNaN',
output: ` declare const x: number; if (!Number.isNaN(x)) {}`,
},
{
messageId: 'conditionFixCastBoolean',
output: ` declare const x: number; if (Boolean(x)) {}`,
},
],
},
{
messageId: 'conditionErrorNumber',
line: 5,
column: 25,
suggestions: [
{
messageId: 'conditionFixCompareZero',
// TODO: fix compare zero suggestion for bigint
output: ` (x: bigint) => x === 0;`,
},
{
// TODO: remove check NaN suggestion for bigint
messageId: 'conditionFixCompareNaN',
output: ` (x: bigint) => Number.isNaN(x);`,
},
{
messageId: 'conditionFixCastBoolean',
output: ` (x: bigint) => !Boolean(x);`,
},
],
},
{
messageId: 'conditionErrorNumber',
line: 6,
column: 38,
suggestions: [
{
messageId: 'conditionFixCompareZero',
output: ` <T extends number>(x: T) => (x !== 0) ? 1 : 0;`,
},
{
messageId: 'conditionFixCompareNaN',
output: ` <T extends number>(x: T) => (!Number.isNaN(x)) ? 1 : 0;`,
},
{
messageId: 'conditionFixCastBoolean',
output: ` <T extends number>(x: T) => (Boolean(x)) ? 1 : 0;`,
},
],
},
{
messageId: 'conditionErrorNumber',
line: 7,
column: 10,
suggestions: [
{
messageId: 'conditionFixCompareZero',
output: ` []["length"] === 0; // doesn't count as array.length when computed`,
},
{
messageId: 'conditionFixCompareNaN',
output: ` Number.isNaN([]["length"]); // doesn't count as array.length when computed`,
},
{
messageId: 'conditionFixCastBoolean',
output: ` !Boolean([]["length"]); // doesn't count as array.length when computed`,
},
],
},
{
messageId: 'conditionErrorNumber',
line: 8,
column: 61,
suggestions: [
{
messageId: 'conditionFixCompareZero',
output: ` declare const a: any[] & { notLength: number }; if (a.notLength !== 0) {}`,
},
{
messageId: 'conditionFixCompareNaN',
output: ` declare const a: any[] & { notLength: number }; if (!Number.isNaN(a.notLength)) {}`,
},
{
messageId: 'conditionFixCastBoolean',
output: ` declare const a: any[] & { notLength: number }; if (Boolean(a.notLength)) {}`,
},
],
},
],
}),
// number (array.length) in boolean context
...batchedSingleLineTests<MessageId, Options>({
options: [{ allowNumber: false }],
code: noFormat`
if (![].length) {}
(a: number[]) => a.length && "..."
<T extends unknown[]>(...a: T) => a.length || "empty";
`,
errors: [
{ messageId: 'conditionErrorNumber', line: 2, column: 6 },
{ messageId: 'conditionErrorNumber', line: 3, column: 26 },
{ messageId: 'conditionErrorNumber', line: 4, column: 43 },
],
output: `
if ([].length === 0) {}
(a: number[]) => (a.length > 0) && "..."
<T extends unknown[]>(...a: T) => (a.length > 0) || "empty";
`,
}),
// mixed `string | number` value in boolean context
...batchedSingleLineTests<MessageId, Options>({
options: [{ allowString: true, allowNumber: true }],
code: noFormat`
declare const x: string | number; if (x) {}
(x: bigint | string) => !x;
<T extends number | bigint | string>(x: T) => x ? 1 : 0;
`,
errors: [
{ messageId: 'conditionErrorOther', line: 2, column: 39 },
{ messageId: 'conditionErrorOther', line: 3, column: 34 },
{ messageId: 'conditionErrorOther', line: 4, column: 55 },
],
}),
// nullable boolean in boolean context
...batchedSingleLineTests<MessageId, Options>({
options: [{ allowNullableBoolean: false }],
code: noFormat`
declare const x: boolean | null; if (x) {}
(x?: boolean) => !x;
<T extends boolean | null | undefined>(x: T) => x ? 1 : 0;
`,
errors: [
{
messageId: 'conditionErrorNullableBoolean',
line: 2,
column: 38,
suggestions: [
{
messageId: 'conditionFixDefaultFalse',
output: `declare const x: boolean | null; if (x ?? false) {}`,
},
{
messageId: 'conditionFixCompareTrue',
output: `declare const x: boolean | null; if (x === true) {}`,
},
],
},
{
messageId: 'conditionErrorNullableBoolean',
line: 3,
column: 27,
suggestions: [
{
messageId: 'conditionFixDefaultFalse',
output: ` (x?: boolean) => !(x ?? false);`,
},
{
messageId: 'conditionFixCompareFalse',
output: ` (x?: boolean) => x === false;`,
},
],
},
{
messageId: 'conditionErrorNullableBoolean',
line: 4,
column: 57,
suggestions: [
{
messageId: 'conditionFixDefaultFalse',
output: ` <T extends boolean | null | undefined>(x: T) => (x ?? false) ? 1 : 0;`,
},
{
messageId: 'conditionFixCompareTrue',
output: ` <T extends boolean | null | undefined>(x: T) => (x === true) ? 1 : 0;`,
},
],
},
],
}),
// nullable object in boolean context
...batchedSingleLineTests<MessageId, Options>({
options: [{ allowNullableObject: false }],
code: noFormat`
declare const x: object | null; if (x) {}
(x?: { a: number }) => !x;
<T extends {} | null | undefined>(x: T) => x ? 1 : 0;
`,
errors: [
{ messageId: 'conditionErrorNullableObject', line: 2, column: 37 },
{ messageId: 'conditionErrorNullableObject', line: 3, column: 33 },
{ messageId: 'conditionErrorNullableObject', line: 4, column: 52 },
],
output: `
declare const x: object | null; if (x != null) {}
(x?: { a: number }) => x == null;
<T extends {} | null | undefined>(x: T) => (x != null) ? 1 : 0;
`,
}),
// nullable string in boolean context
...batchedSingleLineTests<MessageId, Options>({
code: noFormat`
declare const x: string | null; if (x) {}
(x?: string) => !x;
<T extends string | null | undefined>(x: T) => x ? 1 : 0;
function foo(x: '' | 'bar' | null) { if(!x) {} }
`,
errors: [
{
messageId: 'conditionErrorNullableString',
line: 2,
column: 37,
suggestions: [
{
messageId: 'conditionFixCompareNullish',
output: 'declare const x: string | null; if (x != null) {}',
},
{
messageId: 'conditionFixDefaultEmptyString',
output: 'declare const x: string | null; if (x ?? "") {}',
},
{
messageId: 'conditionFixCastBoolean',
output: 'declare const x: string | null; if (Boolean(x)) {}',
},
],
},
{
messageId: 'conditionErrorNullableString',
line: 3,
column: 26,
suggestions: [
{
messageId: 'conditionFixCompareNullish',
output: ' (x?: string) => x == null;',
},
{
messageId: 'conditionFixDefaultEmptyString',
output: ' (x?: string) => !(x ?? "");',
},
{
messageId: 'conditionFixCastBoolean',
output: ' (x?: string) => !Boolean(x);',
},
],
},
{
messageId: 'conditionErrorNullableString',
line: 4,
column: 56,
suggestions: [
{
messageId: 'conditionFixCompareNullish',
output:
' <T extends string | null | undefined>(x: T) => (x != null) ? 1 : 0;',
},
{
messageId: 'conditionFixDefaultEmptyString',
output:
' <T extends string | null | undefined>(x: T) => (x ?? "") ? 1 : 0;',
},
{
messageId: 'conditionFixCastBoolean',
output:
' <T extends string | null | undefined>(x: T) => (Boolean(x)) ? 1 : 0;',
},
],
},
{
messageId: 'conditionErrorNullableString',
line: 5,
column: 50,
suggestions: [
{
messageId: 'conditionFixCompareNullish',
output:
" function foo(x: '' | 'bar' | null) { if(x == null) {} }",
},
{
messageId: 'conditionFixDefaultEmptyString',
output:
" function foo(x: '' | 'bar' | null) { if(!(x ?? \"\")) {} }",
},
{
messageId: 'conditionFixCastBoolean',
output:
" function foo(x: '' | 'bar' | null) { if(!Boolean(x)) {} }",
},
],
},
],
}),
// nullable number in boolean context
...batchedSingleLineTests<MessageId, Options>({
code: noFormat`
declare const x: number | null; if (x) {}
(x?: number) => !x;
<T extends number | null | undefined>(x: T) => x ? 1 : 0;
function foo(x: 0 | 1 | null) { if(!x) {} }
`,
errors: [
{
messageId: 'conditionErrorNullableNumber',
line: 2,
column: 37,
suggestions: [
{
messageId: 'conditionFixCompareNullish',