fix(prefer-tacit): don't check member functions by default

docs/rules/prefer-tacit.md

@@ -41,4 +41,60 @@ function f(x) {
 }
 
 const foo = [1, 2, 3].map(f);
+
+const bar = { f };
+const baz = [1, 2, 3].map((x) => bar.f(x)); // Allowed unless using `checkMemberExpressions`
+```
+
+## Options
+
+This rule accepts an options object of the following type:
+
+```ts
+type Options = {
+ checkMemberExpressions: boolean;
+};
+```
+
+### Default Options
+
+```ts
+type Options = {
+ checkMemberExpressions: false;
+};
+```
+
+### `checkMemberExpressions`
+
+If `true`, calls of member expressions are checked as well.
+If `false`, only calls of identifiers are checked.
+
+#### ❌ Incorrect
+
+<!-- eslint-skip -->
+
+```ts
+/* eslint functional/prefer-tacit: ["error", { "checkMemberExpressions": true }] */
+
+const bar = {
+ f(x) {
+ return x + 1;
+ }
+}
+
+const foo = [1, 2, 3].map((x) => bar.f(x));
+```
+
+#### ✅ Correct
+
+```ts
+/* eslint functional/prefer-tacit: ["error", { "checkMemberExpressions": true }] */
+
+const bar = {
+ f(x) {
+ return x + 1;
+ }
+}
+
+const foo = [1, 2, 3].map(bar.f.bind(bar));
 ```

src/rules/prefer-tacit.ts

@@ -25,6 +25,7 @@ import {
  isBlockStatement,
  isCallExpression,
  isIdentifier,
+ isMemberExpression,
  isReturnStatement,
 } from "#eslint-plugin-functional/utils/type-guards";
 
@@ -41,17 +42,35 @@ export const fullName = `${ruleNameScope}/${name}`;
 /**
  * The options this rule can take.
  */
-type Options = [];
+type Options = [
+ {
+ checkMemberExpressions: boolean;
+ },
+];
 
 /**
  * The schema for the rule options.
  */
-const schema: JSONSchema4[] = [];
+const schema: JSONSchema4[] = [
+ {
+ type: "object",
+ properties: {
+ checkMemberExpressions: {
+ type: "boolean",
+ },
+ },
+ additionalProperties: false,
+ },
+];
 
 /**
  * The default options for the rule.
  */
-const defaultOptions: Options = [];
+const defaultOptions: Options = [
+ {
+ checkMemberExpressions: false,
+ },
+];
 
 /**
  * The possible error messages.
@@ -135,8 +154,12 @@ function fixFunctionCallToReference(
 
  return [
  fixer.replaceText(
- node as TSESTree.Node,
- context.sourceCode.getText(caller.callee as TSESTree.Node),
+ node,
+ isMemberExpression(caller.callee)
+ ? `${context.sourceCode.getText(
+ caller.callee,
+ )}.bind(${context.sourceCode.getText(caller.callee.object)})`
+ : context.sourceCode.getText(caller.callee),
  ),
  ];
 }
@@ -196,6 +219,15 @@ function getCallDescriptors(
  options: Options,
  caller: TSESTree.CallExpression,
 ): Array<ReportDescriptor<keyof typeof errorMessages>> {
+ const [{ checkMemberExpressions }] = options;
+
+ if (
+ !isIdentifier(caller.callee) &&
+ !(checkMemberExpressions && isMemberExpression(caller.callee))
+ ) {
+ return [];
+ }
+
  if (
  node.params.length === caller.arguments.length &&
  node.params.every((param, index) => {

tests/rules/prefer-tacit/ts/invalid.ts

@@ -293,6 +293,53 @@ const tests: Array<
  },
  ],
  },
+ // Member Call Expression
+ {
+ code: dedent`
+ [''].filter(str => /a/.test(str));
+ `,
+ optionsSet: [[{ checkMemberExpressions: true }]],
+ errors: [
+ {
+ messageId: "generic",
+ type: AST_NODE_TYPES.ArrowFunctionExpression,
+ line: 1,
+ column: 13,
+ suggestions: [
+ {
+ messageId: "generic",
+ output: dedent`
+ [''].filter(/a/.test.bind(/a/));
+ `,
+ },
+ ],
+ },
+ ],
+ },
+ {
+ code: dedent`
+ declare const a: { b(arg: string): string; };
+ function foo(x) { return a.b(x); }
+ `,
+ optionsSet: [[{ checkMemberExpressions: true }]],
+ errors: [
+ {
+ messageId: "generic",
+ type: AST_NODE_TYPES.FunctionDeclaration,
+ line: 2,
+ column: 1,
+ suggestions: [
+ {
+ messageId: "generic",
+ output: dedent`
+ declare const a: { b(arg: string): string; };
+ const foo = a.b.bind(a);
+ `,
+ },
+ ],
+ },
+ ],
+ },
 ];
 
 export default tests;

tests/rules/prefer-tacit/ts/valid.ts

@@ -86,6 +86,20 @@ const tests: Array<ValidTestCaseSet<OptionsOf<typeof rule>>> = [
  dependencyConstraints: { typescript: "4.7.0" },
  optionsSet: [[]],
  },
+ // Member Call Expression
+ {
+ code: dedent`
+ [''].filter(str => /a/.test(str))
+ `,
+ optionsSet: [[{ checkMemberExpressions: false }]],
+ },
+ {
+ code: dedent`
+ declare const a: { b(arg: string): string; };
+ function foo(x) { return a.b(x); }
+ `,
+ optionsSet: [[{ checkMemberExpressions: false }]],
+ },
 ];
 
 export default tests;