refactor: remove unnecessary functions from getTypeServices (#23)

These utility functions are unused or replaceable with built-in
`ESLintUtils.getTypeServices` or `ts-api-utils`.

Author: JasonWeinzierl

src/etc/get-type-services.ts

@@ -1,5 +1,4 @@
 import { ESLintUtils, TSESLint, TSESTree } from '@typescript-eslint/utils';
-import * as tsutils from 'ts-api-utils';
 import ts from 'typescript';
 import { couldBeFunction } from './could-be-function';
 import { couldBeType as tsutilsEtcCouldBeType } from './could-be-type';
@@ -18,7 +17,7 @@ export function getTypeServices<
     name: string | RegExp,
     qualified?: { name: RegExp },
   ): boolean => {
-    const type = getType(node);
+    const type = getTypeAtLocation(node);
     return tsutilsEtcCouldBeType(
       type,
       name,
@@ -56,19 +55,14 @@ export function getTypeServices<
     );
   };
 
-  const getType = (node: TSESTree.Node): ts.Type => {
-    return getTypeAtLocation(node);
-  };
-
   return {
     couldBeBehaviorSubject: (node: TSESTree.Node) =>
       couldBeType(node, 'BehaviorSubject'),
-    couldBeError: (node: TSESTree.Node) => couldBeType(node, 'Error'),
     couldBeFunction: (node: TSESTree.Node) => {
       if (isArrowFunctionExpression(node) || isFunctionDeclaration(node)) {
         return true;
       }
-      return couldBeFunction(getType(node));
+      return couldBeFunction(getTypeAtLocation(node));
     },
     couldBeMonoTypeOperatorFunction: (node: TSESTree.Node) =>
       couldBeType(node, 'MonoTypeOperatorFunction'),
@@ -79,10 +73,5 @@ export function getTypeServices<
     couldReturnObservable: (node: TSESTree.Node) =>
       couldReturnType(node, 'Observable'),
     couldReturnType,
-    getType,
-    isAny: (node: TSESTree.Node) => tsutils.isIntrinsicAnyType(getType(node)),
-    isReferenceType: (node: TSESTree.Node) => tsutils.isTypeReference(getType(node)),
-    isUnknown: (node: TSESTree.Node) => tsutils.isIntrinsicUnknownType(getType(node)),
-    typeChecker,
   };
 }

src/rules/no-cyclic-action.ts

@@ -1,8 +1,8 @@
-import { TSESTree as es } from '@typescript-eslint/utils';
+import { TSESTree as es, ESLintUtils } from '@typescript-eslint/utils';
 import { stripIndent } from 'common-tags';
 import ts from 'typescript';
 import { defaultObservable } from '../constants';
-import { getTypeServices, isCallExpression, isIdentifier } from '../etc';
+import { isCallExpression, isIdentifier } from '../etc';
 import { ruleCreator } from '../utils';
 
 function isTypeReference(type: ts.Type): type is ts.TypeReference {
@@ -44,7 +44,8 @@ export const noCyclicActionRule = ruleCreator({
     const { observable = defaultObservable } = config;
     const observableRegExp = new RegExp(observable);
 
-    const { getType, typeChecker } = getTypeServices(context);
+    const { getTypeAtLocation, program } = ESLintUtils.getParserServices(context);
+    const typeChecker = program.getTypeChecker();
 
     function checkNode(pipeCallExpression: es.CallExpression) {
       const operatorCallExpression = pipeCallExpression.arguments.find(
@@ -56,7 +57,7 @@ export const noCyclicActionRule = ruleCreator({
       if (!operatorCallExpression) {
         return;
       }
-      const operatorType = getType(operatorCallExpression);
+      const operatorType = getTypeAtLocation(operatorCallExpression);
       const [signature] = typeChecker.getSignaturesOfType(
         operatorType,
         ts.SignatureKind.Call,
@@ -75,7 +76,7 @@ export const noCyclicActionRule = ruleCreator({
         return;
       }
 
-      const pipeType = getType(pipeCallExpression);
+      const pipeType = getTypeAtLocation(pipeCallExpression);
       if (!isTypeReference(pipeType)) {
         return;
       }

src/rules/no-unbound-methods.ts

@@ -1,4 +1,4 @@
-import { TSESTree as es } from '@typescript-eslint/utils';
+import { TSESTree as es, ESLintUtils } from '@typescript-eslint/utils';
 import {
   getTypeServices,
   isCallExpression,
@@ -21,13 +21,13 @@ export const noUnboundMethodsRule = ruleCreator({
   },
   name: 'no-unbound-methods',
   create: (context) => {
-    const { couldBeObservable, couldBeSubscription, getType }
-      = getTypeServices(context);
+    const { getTypeAtLocation } = ESLintUtils.getParserServices(context);
+    const { couldBeObservable, couldBeSubscription } = getTypeServices(context);
     const nodeMap = new WeakMap<es.Node, void>();
 
     function mapArguments(node: es.CallExpression | es.NewExpression) {
       node.arguments.filter(isMemberExpression).forEach((arg) => {
-        const argType = getType(arg);
+        const argType = getTypeAtLocation(arg);
         if (argType.getCallSignatures().length > 0) {
           nodeMap.set(arg);
         }

src/rules/no-unsafe-subject-next.ts

@@ -1,10 +1,10 @@
-import { TSESTree as es } from '@typescript-eslint/utils';
+import { TSESTree as es, ESLintUtils } from '@typescript-eslint/utils';
 import * as tsutils from 'ts-api-utils';
 import ts from 'typescript';
 import {
   couldBeType,
-  getTypeServices,
-  isMemberExpression } from '../etc';
+  isMemberExpression,
+} from '../etc';
 import { ruleCreator } from '../utils';
 
 export const noUnsafeSubjectNext = ruleCreator({
@@ -23,13 +23,15 @@ export const noUnsafeSubjectNext = ruleCreator({
   },
   name: 'no-unsafe-subject-next',
   create: (context) => {
-    const { getType, typeChecker } = getTypeServices(context);
+    const { getTypeAtLocation, program } = ESLintUtils.getParserServices(context);
+    const typeChecker = program.getTypeChecker();
+
     return {
       [`CallExpression[callee.property.name='next']`]: (
         node: es.CallExpression,
       ) => {
         if (node.arguments.length === 0 && isMemberExpression(node.callee)) {
-          const type = getType(node.callee.object);
+          const type = getTypeAtLocation(node.callee.object);
           if (tsutils.isTypeReference(type) && couldBeType(type, 'Subject')) {
             const [typeArg] = typeChecker.getTypeArguments(type);
             if (tsutils.isTypeFlagSet(typeArg, ts.TypeFlags.Any)) {

src/rules/throw-error.ts

@@ -20,11 +20,11 @@ export const throwErrorRule = ruleCreator({
   },
   name: 'throw-error',
   create: (context) => {
-    const { esTreeNodeToTSNodeMap, program } = ESLintUtils.getParserServices(context);
-    const { couldBeObservable, getType } = getTypeServices(context);
+    const { esTreeNodeToTSNodeMap, program, getTypeAtLocation } = ESLintUtils.getParserServices(context);
+    const { couldBeObservable } = getTypeServices(context);
 
     function checkNode(node: es.Node) {
-      let type = getType(node);
+      let type = getTypeAtLocation(node);
       if (couldBeFunction(type)) {
         const tsNode = esTreeNodeToTSNodeMap.get(node);
         const annotation = (tsNode as ts.ArrowFunction).type;