/
prefer-readonly-parameter-types.ts
115 lines (108 loc) · 3.3 KB
/
prefer-readonly-parameter-types.ts
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import {
AST_NODE_TYPES,
TSESTree,
} from '@typescript-eslint/experimental-utils';
import { ESLintTypeUtils } from '@typescript-eslint/type-utils';
import * as util from '../util';
type Options = [
{
checkParameterProperties?: boolean;
ignoreInferredTypes?: boolean;
} & ESLintTypeUtils.ReadonlynessOptions,
];
type MessageIds = 'shouldBeReadonly';
export default util.createRule<Options, MessageIds>({
name: 'prefer-readonly-parameter-types',
meta: {
type: 'suggestion',
docs: {
description:
'Requires that function parameters are typed as readonly to prevent accidental mutation of inputs',
recommended: false,
requiresTypeChecking: true,
},
schema: [
{
type: 'object',
additionalProperties: false,
properties: {
checkParameterProperties: {
type: 'boolean',
},
ignoreInferredTypes: {
type: 'boolean',
},
...ESLintTypeUtils.readonlynessOptionsSchema.properties,
},
},
],
messages: {
shouldBeReadonly: 'Parameter should be a read only type.',
},
},
defaultOptions: [
{
checkParameterProperties: true,
ignoreInferredTypes: false,
...ESLintTypeUtils.readonlynessOptionsDefaults,
},
],
create(
context,
[{ checkParameterProperties, ignoreInferredTypes, treatMethodsAsReadonly }],
) {
const { esTreeNodeToTSNodeMap, program } = util.getParserServices(context);
const checker = program.getTypeChecker();
return {
[[
AST_NODE_TYPES.ArrowFunctionExpression,
AST_NODE_TYPES.FunctionDeclaration,
AST_NODE_TYPES.FunctionExpression,
AST_NODE_TYPES.TSCallSignatureDeclaration,
AST_NODE_TYPES.TSConstructSignatureDeclaration,
AST_NODE_TYPES.TSDeclareFunction,
AST_NODE_TYPES.TSEmptyBodyFunctionExpression,
AST_NODE_TYPES.TSFunctionType,
AST_NODE_TYPES.TSMethodSignature,
].join(', ')](
node:
| TSESTree.ArrowFunctionExpression
| TSESTree.FunctionDeclaration
| TSESTree.FunctionExpression
| TSESTree.TSCallSignatureDeclaration
| TSESTree.TSConstructSignatureDeclaration
| TSESTree.TSDeclareFunction
| TSESTree.TSEmptyBodyFunctionExpression
| TSESTree.TSFunctionType
| TSESTree.TSMethodSignature,
): void {
for (const param of node.params) {
if (
!checkParameterProperties &&
param.type === AST_NODE_TYPES.TSParameterProperty
) {
continue;
}
const actualParam =
param.type === AST_NODE_TYPES.TSParameterProperty
? param.parameter
: param;
if (ignoreInferredTypes && actualParam.typeAnnotation == null) {
continue;
}
const tsNode = esTreeNodeToTSNodeMap.get(actualParam);
const type = checker.getTypeAtLocation(tsNode);
const isReadOnly = ESLintTypeUtils.isTypeReadonly(checker, type, {
treatMethodsAsReadonly: treatMethodsAsReadonly!,
});
if (!isReadOnly) {
context.report({
node: actualParam,
messageId: 'shouldBeReadonly',
});
}
}
},
};
},
});