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fix(eslint-plugin): [no-unnecessary-condition] better message when comparing between literal types #10454

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Merged
merged 4 commits into from
Dec 14, 2024
Merged

fix(eslint-plugin): [no-unnecessary-condition] better message when comparing between literal types #10454

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ad5760a
better boolean literal compare message
kirkwaiblinger Dec 5, 2024
ef65a13
rename
kirkwaiblinger Dec 6, 2024
160d49a
Merge branch 'main' into nuc
kirkwaiblinger Dec 14, 2024
3d1186a
use typeToString
kirkwaiblinger Dec 14, 2024
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11 changes: 7 additions & 4 deletions packages/eslint-plugin/src/rules/no-unnecessary-condition.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -183,7 +183,7 @@ export type MessageId =
| 'alwaysNullish'
| 'alwaysTruthy'
| 'alwaysTruthyFunc'
| 'literalBooleanExpression'
| 'comparisonBetweenLiteralTypes'
| 'never'
| 'neverNullish'
| 'neverOptionalChain'
Expand Down Expand Up @@ -211,8 +211,8 @@ export default createRule<Options, MessageId>({
alwaysTruthy: 'Unnecessary conditional, value is always truthy.',
alwaysTruthyFunc:
'This callback should return a conditional, but return is always truthy.',
literalBooleanExpression:
'Unnecessary conditional, comparison is always {{trueOrFalse}}. Both sides of the comparison always have a literal type.',
comparisonBetweenLiteralTypes:
'Unnecessary conditional, comparison is always {{trueOrFalse}}, since `{{left}} {{operator}} {{right}}` is {{trueOrFalse}}.',
never: 'Unnecessary conditional, value is `never`.',
neverNullish:
'Unnecessary conditional, expected left-hand side of `??` operator to be possibly null or undefined.',
Expand Down Expand Up @@ -489,8 +489,11 @@ export default createRule<Options, MessageId>({

context.report({
node,
messageId: 'literalBooleanExpression',
messageId: 'comparisonBetweenLiteralTypes',
data: {
left: checker.typeToString(leftType),
operator,
right: checker.typeToString(rightType),
trueOrFalse: conditionIsTrue ? 'true' : 'false',
},
});
Expand Down
193 changes: 156 additions & 37 deletions packages/eslint-plugin/tests/rules/no-unnecessary-condition.test.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -1048,9 +1048,14 @@ switch (b1) {
{ column: 18, line: 16, messageId: 'alwaysTruthy' },
{
column: 8,
data: { trueOrFalse: 'true' },
data: {
left: 'true',
operator: '===',
right: 'true',
trueOrFalse: 'true',
},
line: 18,
messageId: 'literalBooleanExpression',
messageId: 'comparisonBetweenLiteralTypes',
},
],
},
Expand Down Expand Up @@ -1144,10 +1149,13 @@ function test(a: 'a') {
{
column: 10,
data: {
left: '"a"',
operator: '===',
right: '"a"',
trueOrFalse: 'true',
},
line: 3,
messageId: 'literalBooleanExpression',
messageId: 'comparisonBetweenLiteralTypes',
},
],
},
Expand All @@ -1160,10 +1168,13 @@ a > b;
errors: [
{
data: {
left: '"34"',
operator: '>',
right: '"56"',
trueOrFalse: 'false',
},
line: 4,
messageId: 'literalBooleanExpression',
messageId: 'comparisonBetweenLiteralTypes',
},
],
},
Expand All @@ -1175,9 +1186,14 @@ if (y === 0) {
`,
errors: [
{
data: { trueOrFalse: 'false' },
data: {
left: '1',
operator: '===',
right: '0',
trueOrFalse: 'false',
},
line: 3,
messageId: 'literalBooleanExpression',
messageId: 'comparisonBetweenLiteralTypes',
},
],
},
Expand All @@ -1189,9 +1205,14 @@ if (1 == '1') {
`,
errors: [
{
data: { trueOrFalse: 'true' },
data: {
left: '1',
operator: '==',
right: '"1"',
trueOrFalse: 'true',
},
line: 3,
messageId: 'literalBooleanExpression',
messageId: 'comparisonBetweenLiteralTypes',
},
],
},
Expand All @@ -1201,9 +1222,14 @@ if (1 == '1') {
`,
errors: [
{
data: { trueOrFalse: 'false' },
data: {
left: '2.3',
operator: '>',
right: '2.3',
trueOrFalse: 'false',
},
line: 2,
messageId: 'literalBooleanExpression',
messageId: 'comparisonBetweenLiteralTypes',
},
],
},
Expand All @@ -1213,9 +1239,14 @@ if (1 == '1') {
`,
errors: [
{
data: { trueOrFalse: 'true' },
data: {
left: '2.3',
operator: '>=',
right: '2.3',
trueOrFalse: 'true',
},
line: 2,
messageId: 'literalBooleanExpression',
messageId: 'comparisonBetweenLiteralTypes',
},
],
},
Expand All @@ -1225,9 +1256,14 @@ if (1 == '1') {
`,
errors: [
{
data: { trueOrFalse: 'false' },
data: {
left: '2n',
operator: '<',
right: '2n',
trueOrFalse: 'false',
},
line: 2,
messageId: 'literalBooleanExpression',
messageId: 'comparisonBetweenLiteralTypes',
},
],
},
Expand All @@ -1237,9 +1273,14 @@ if (1 == '1') {
`,
errors: [
{
data: { trueOrFalse: 'true' },
data: {
left: '2n',
operator: '<=',
right: '2n',
trueOrFalse: 'true',
},
line: 2,
messageId: 'literalBooleanExpression',
messageId: 'comparisonBetweenLiteralTypes',
},
],
},
Expand All @@ -1249,9 +1290,14 @@ if (1 == '1') {
`,
errors: [
{
data: { trueOrFalse: 'true' },
data: {
left: '-2n',
operator: '!==',
right: '2n',
trueOrFalse: 'true',
},
line: 2,
messageId: 'literalBooleanExpression',
messageId: 'comparisonBetweenLiteralTypes',
},
],
},
Expand All @@ -1263,9 +1309,14 @@ if (1 == '2') {
`,
errors: [
{
data: { trueOrFalse: 'false' },
data: {
left: '1',
operator: '==',
right: '"2"',
trueOrFalse: 'false',
},
line: 3,
messageId: 'literalBooleanExpression',
messageId: 'comparisonBetweenLiteralTypes',
},
],
},
Expand All @@ -1277,9 +1328,14 @@ if (1 != '2') {
`,
errors: [
{
data: { trueOrFalse: 'true' },
data: {
left: '1',
operator: '!=',
right: '"2"',
trueOrFalse: 'true',
},
line: 3,
messageId: 'literalBooleanExpression',
messageId: 'comparisonBetweenLiteralTypes',
},
],
},
Expand All @@ -1298,10 +1354,38 @@ if (x === Foo.a) {
{
column: 5,
data: {
left: 'Foo.a',
operator: '===',
right: 'Foo.a',
trueOrFalse: 'true',
},
line: 8,
messageId: 'literalBooleanExpression',
messageId: 'comparisonBetweenLiteralTypes',
},
],
},
{
code: `
enum Foo {
a = 1,
b = 2,
}

const x = Foo.a;
if (x === 1) {
}
`,
errors: [
{
column: 5,
data: {
left: 'Foo.a',
operator: '===',
right: 1,
trueOrFalse: 'true',
},
line: 8,
messageId: 'comparisonBetweenLiteralTypes',
},
],
},
Expand All @@ -1317,11 +1401,16 @@ function takesMaybeValue(a: null | object) {
errors: [
{
column: 14,
data: { trueOrFalse: 'true' },
data: {
left: 'null',
operator: '==',
right: 'undefined',
trueOrFalse: 'true',
},
endColumn: 28,
endLine: 4,
line: 4,
messageId: 'literalBooleanExpression',
messageId: 'comparisonBetweenLiteralTypes',
},
],
},
Expand All @@ -1337,11 +1426,16 @@ function takesMaybeValue(a: null | object) {
errors: [
{
column: 14,
data: { trueOrFalse: 'false' },
data: {
left: 'null',
operator: '===',
right: 'undefined',
trueOrFalse: 'false',
},
endColumn: 29,
endLine: 4,
line: 4,
messageId: 'literalBooleanExpression',
messageId: 'comparisonBetweenLiteralTypes',
},
],
},
Expand All @@ -1357,11 +1451,16 @@ function takesMaybeValue(a: null | object) {
errors: [
{
column: 14,
data: { trueOrFalse: 'false' },
data: {
left: 'null',
operator: '!=',
right: 'undefined',
trueOrFalse: 'false',
},
endColumn: 28,
endLine: 4,
line: 4,
messageId: 'literalBooleanExpression',
messageId: 'comparisonBetweenLiteralTypes',
},
],
},
Expand All @@ -1377,11 +1476,16 @@ function takesMaybeValue(a: null | object) {
errors: [
{
column: 14,
data: { trueOrFalse: 'true' },
data: {
left: 'null',
operator: '!==',
right: 'undefined',
trueOrFalse: 'true',
},
endColumn: 29,
endLine: 4,
line: 4,
messageId: 'literalBooleanExpression',
messageId: 'comparisonBetweenLiteralTypes',
},
],
},
Expand All @@ -1391,8 +1495,13 @@ true === false;
`,
errors: [
{
data: { trueOrFalse: 'false' },
messageId: 'literalBooleanExpression',
data: {
left: 'true',
operator: '===',
right: 'false',
trueOrFalse: 'false',
},
messageId: 'comparisonBetweenLiteralTypes',
},
],
},
Expand All @@ -1402,8 +1511,13 @@ true === true;
`,
errors: [
{
data: { trueOrFalse: 'true' },
messageId: 'literalBooleanExpression',
data: {
left: 'true',
operator: '===',
right: 'true',
trueOrFalse: 'true',
},
messageId: 'comparisonBetweenLiteralTypes',
},
],
},
Expand All @@ -1413,8 +1527,13 @@ true === undefined;
`,
errors: [
{
data: { trueOrFalse: 'false' },
messageId: 'literalBooleanExpression',
data: {
left: 'true',
operator: '===',
right: 'undefined',
trueOrFalse: 'false',
},
messageId: 'comparisonBetweenLiteralTypes',
},
],
},
Expand Down
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