/
prefer-equality-matcher.ts
123 lines (108 loc) · 3.63 KB
/
prefer-equality-matcher.ts
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import { AST_NODE_TYPES, TSESLint } from '@typescript-eslint/utils';
import {
EqualityMatcher,
ModifierName,
createRule,
getAccessorValue,
getFirstMatcherArg,
isBooleanLiteral,
parseJestFnCall,
} from './utils';
export default createRule({
name: __filename,
meta: {
docs: {
category: 'Best Practices',
description: 'Suggest using the built-in equality matchers',
recommended: false,
suggestion: true,
},
messages: {
useEqualityMatcher: 'Prefer using one of the equality matchers instead',
suggestEqualityMatcher: 'Use `{{ equalityMatcher }}`',
},
hasSuggestions: true,
type: 'suggestion',
schema: [],
},
defaultOptions: [],
create(context) {
return {
CallExpression(node) {
const jestFnCall = parseJestFnCall(node, context);
if (jestFnCall?.type !== 'expect' || jestFnCall.args.length === 0) {
return;
}
const { parent: expect } = jestFnCall.head.node;
if (expect?.type !== AST_NODE_TYPES.CallExpression) {
return;
}
const {
arguments: [comparison],
range: [, expectCallEnd],
} = expect;
const { matcher } = jestFnCall;
const matcherArg = getFirstMatcherArg(jestFnCall);
if (
comparison?.type !== AST_NODE_TYPES.BinaryExpression ||
(comparison.operator !== '===' && comparison.operator !== '!==') ||
!EqualityMatcher.hasOwnProperty(getAccessorValue(matcher)) ||
!isBooleanLiteral(matcherArg)
) {
return;
}
const matcherValue = matcherArg.value;
const [modifier] = jestFnCall.modifiers;
const hasNot = jestFnCall.modifiers.some(
nod => getAccessorValue(nod) === 'not',
);
// we need to negate the expectation if the current expected
// value is itself negated by the "not" modifier
const addNotModifier =
(comparison.operator === '!==' ? !matcherValue : matcherValue) ===
hasNot;
const buildFixer =
(equalityMatcher: string): TSESLint.ReportFixFunction =>
fixer => {
const sourceCode = context.getSourceCode();
// preserve the existing modifier if it's not a negation
let modifierText =
modifier && getAccessorValue(modifier) !== 'not'
? `.${getAccessorValue(modifier)}`
: '';
if (addNotModifier) {
modifierText += `.${ModifierName.not}`;
}
return [
// replace the comparison argument with the left-hand side of the comparison
fixer.replaceText(
comparison,
sourceCode.getText(comparison.left),
),
// replace the current matcher & modifier with the preferred matcher
fixer.replaceTextRange(
[expectCallEnd, matcher.parent.range[1]],
`${modifierText}.${equalityMatcher}`,
),
// replace the matcher argument with the right-hand side of the comparison
fixer.replaceText(
matcherArg,
sourceCode.getText(comparison.right),
),
];
};
context.report({
messageId: 'useEqualityMatcher',
suggest: ['toBe', 'toEqual', 'toStrictEqual'].map(
equalityMatcher => ({
messageId: 'suggestEqualityMatcher',
data: { equalityMatcher },
fix: buildFixer(equalityMatcher),
}),
),
node: matcher,
});
},
};
},
});