TS: Enable strict mode

src/__tests__/starWarsSchema.ts

@@ -98,7 +98,7 @@ const episodeEnum = new GraphQLEnumType({
  *     secretBackstory: String
  *   }
  */
-const characterInterface = new GraphQLInterfaceType({
+const characterInterface: GraphQLInterfaceType = new GraphQLInterfaceType({
   name: 'Character',
   description: 'A character in the Star Wars Trilogy',
   fields: () => ({

src/error/GraphQLError.ts

@@ -14,15 +14,6 @@ import { printLocation, printSourceLocation } from '../language/printLocation';
  * GraphQL document and/or execution result that correspond to the Error.
  */
 export class GraphQLError extends Error {
-  /**
-   * A message describing the Error for debugging purposes.
-   *
-   * Enumerable, and appears in the result of JSON.stringify().
-   *
-   * Note: should be treated as readonly, despite invariant usage.
-   */
-  message: string;
-
   /**
    * An array of { line, column } locations within the source GraphQL document
    * which correspond to this error.

src/error/__tests__/formatError-test.ts

@@ -45,10 +45,12 @@ describe('formatError: default error formatter', () => {
   });
 
   it('rejects null and undefined errors', () => {
+    // @ts-expect-error (formatError expects a value)
     expect(() => formatError(undefined)).to.throw(
       'Received null or undefined error.',
     );
 
+    // @ts-expect-error (formatError expects a value)
     expect(() => formatError(null)).to.throw(
       'Received null or undefined error.',
     );

src/error/locatedError.ts

@@ -22,21 +22,20 @@ export function locatedError(
       : new Error('Unexpected error value: ' + inspect(rawOriginalError));
 
   // Note: this uses a brand-check to support GraphQL errors originating from other contexts.
-  // @ts-expect-error FIXME: TS Conversion
-  if (Array.isArray(originalError.path)) {
-    // @ts-expect-error
+  if (isLocatedGraphQLError(originalError)) {
     return originalError;
   }
 
   return new GraphQLError(
     originalError.message,
-    // @ts-expect-error FIXME
-    originalError.nodes ?? nodes,
-    // @ts-expect-error FIXME
-    originalError.source,
-    // @ts-expect-error FIXME
-    originalError.positions,
+    (originalError as GraphQLError).nodes ?? nodes,
+    (originalError as GraphQLError).source,
+    (originalError as GraphQLError).positions,
     path,
     originalError,
   );
 }
+
+function isLocatedGraphQLError(error: any): error is GraphQLError {
+  return Array.isArray(error.path);
+}

src/execution/__tests__/abstract-test.ts

@@ -577,9 +577,9 @@ describe('Execute: Handles execution of abstract types', () => {
     );
 
     // FIXME: workaround since we can't inject resolveType into SDL
-    assertInterfaceType(schema.getType('Pet')).resolveType =
-      // @ts-expect-error
-      () => schema.getType('Cat');
+    // @ts-expect-error
+    assertInterfaceType(schema.getType('Pet')).resolveType = () =>
+      schema.getType('Cat');
     expectError({ forTypeName: undefined }).toEqual(
       'Support for returning GraphQLObjectType from resolveType was removed in graphql-js@16.0.0 please return type name instead.',
     );

src/execution/__tests__/executor-test.ts

@@ -94,7 +94,7 @@ describe('Execute: Handles basic execution tasks', () => {
       return Promise.resolve(data);
     }
 
-    const DataType = new GraphQLObjectType({
+    const DataType: GraphQLObjectType = new GraphQLObjectType({
       name: 'DataType',
       fields: () => ({
         a: { type: GraphQLString },
@@ -185,7 +185,7 @@ describe('Execute: Handles basic execution tasks', () => {
   });
 
   it('merges parallel fragments', () => {
-    const Type = new GraphQLObjectType({
+    const Type: GraphQLObjectType = new GraphQLObjectType({
       name: 'Type',
       fields: () => ({
         a: { type: GraphQLString, resolve: () => 'Apple' },
@@ -624,7 +624,7 @@ describe('Execute: Handles basic execution tasks', () => {
   });
 
   it('Full response path is included for non-nullable fields', () => {
-    const A = new GraphQLObjectType({
+    const A: GraphQLObjectType = new GraphQLObjectType({
       name: 'A',
       fields: () => ({
         nullableA: {

src/execution/__tests__/schema-test.ts

@@ -29,7 +29,7 @@ describe('Execute: Handles execution with a complex schema', () => {
       },
     });
 
-    const BlogAuthor = new GraphQLObjectType({
+    const BlogAuthor: GraphQLObjectType = new GraphQLObjectType({
       name: 'Author',
       fields: () => ({
         id: { type: GraphQLString },

src/execution/__tests__/union-interface-test.ts

@@ -65,14 +65,14 @@ const NamedType = new GraphQLInterfaceType({
   },
 });
 
-const LifeType = new GraphQLInterfaceType({
+const LifeType: GraphQLInterfaceType = new GraphQLInterfaceType({
   name: 'Life',
   fields: () => ({
     progeny: { type: new GraphQLList(LifeType) },
   }),
 });
 
-const MammalType = new GraphQLInterfaceType({
+const MammalType: GraphQLInterfaceType = new GraphQLInterfaceType({
   name: 'Mammal',
   interfaces: [LifeType],
   fields: () => ({
@@ -82,7 +82,7 @@ const MammalType = new GraphQLInterfaceType({
   }),
 });
 
-const DogType = new GraphQLObjectType({
+const DogType: GraphQLObjectType = new GraphQLObjectType({
   name: 'Dog',
   interfaces: [MammalType, LifeType, NamedType],
   fields: () => ({
@@ -95,7 +95,7 @@ const DogType = new GraphQLObjectType({
   isTypeOf: (value) => value instanceof Dog,
 });
 
-const CatType = new GraphQLObjectType({
+const CatType: GraphQLObjectType = new GraphQLObjectType({
   name: 'Cat',
   interfaces: [MammalType, LifeType, NamedType],
   fields: () => ({
@@ -125,7 +125,7 @@ const PetType = new GraphQLUnionType({
   },
 });
 
-const PersonType = new GraphQLObjectType({
+const PersonType: GraphQLObjectType = new GraphQLObjectType({
   name: 'Person',
   interfaces: [NamedType, MammalType, LifeType],
   fields: () => ({
@@ -503,7 +503,7 @@ describe('Execute: Union and intersection types', () => {
     let encounteredSchema;
     let encounteredRootValue;
 
-    const NamedType2 = new GraphQLInterfaceType({
+    const NamedType2: GraphQLInterfaceType = new GraphQLInterfaceType({
       name: 'Named',
       fields: {
         name: { type: GraphQLString },
@@ -516,7 +516,7 @@ describe('Execute: Union and intersection types', () => {
       },
     });
 
-    const PersonType2 = new GraphQLObjectType({
+    const PersonType2: GraphQLObjectType = new GraphQLObjectType({
       name: 'Person',
       interfaces: [NamedType2],
       fields: {

src/execution/__tests__/variables-test.ts

@@ -7,7 +7,10 @@ import { invariant } from '../../jsutils/invariant';
 import { Kind } from '../../language/kinds';
 import { parse } from '../../language/parser';
 
-import type { GraphQLArgumentConfig } from '../../type/definition';
+import type {
+  GraphQLFieldConfig,
+  GraphQLArgumentConfig,
+} from '../../type/definition';
 import { GraphQLSchema } from '../../type/schema';
 import { GraphQLString } from '../../type/scalars';
 import {
@@ -64,7 +67,9 @@ const TestEnum = new GraphQLEnumType({
   },
 });
 
-function fieldWithInputArg(inputArg: GraphQLArgumentConfig) {
+function fieldWithInputArg(
+  inputArg: GraphQLArgumentConfig,
+): GraphQLFieldConfig<any, any> {
   return {
     type: GraphQLString,
     args: { input: inputArg },

src/execution/execute.ts

@@ -180,7 +180,7 @@ export function execute(args: ExecutionArgs): PromiseOrValue<ExecutionResult> {
   );
 
   // Return early errors if execution context failed.
-  if (Array.isArray(exeContext)) {
+  if (!('schema' in exeContext)) {
     return { errors: exeContext };
   }
 
@@ -191,9 +191,7 @@ export function execute(args: ExecutionArgs): PromiseOrValue<ExecutionResult> {
   // field and its descendants will be omitted, and sibling fields will still
   // be executed. An execution which encounters errors will still result in a
   // resolved Promise.
-  // @ts-expect-error FIXME: TS Conversion
   const data = executeOperation(exeContext, exeContext.operation, rootValue);
-  // @ts-expect-error FIXME: TS Conversion
   return buildResponse(exeContext, data);
 }
 

src/execution/values.ts

@@ -77,7 +77,7 @@ function coerceVariableValues(
   inputs: { readonly [variable: string]: unknown },
   onError: (error: GraphQLError) => void,
 ): { [variable: string]: unknown } {
-  const coercedValues = {};
+  const coercedValues: { [variable: string]: unknown } = {};
   for (const varDefNode of varDefNodes) {
     const varName = varDefNode.variable.name.value;
     const varType = typeFromAST(schema, varDefNode.type);
@@ -162,7 +162,7 @@ export function getArgumentValues(
   node: FieldNode | DirectiveNode,
   variableValues?: Maybe<ObjMap<unknown>>,
 ): { [argument: string]: unknown } {
-  const coercedValues = {};
+  const coercedValues: { [argument: string]: unknown } = {};
 
   // istanbul ignore next (See: 'https://github.com/graphql/graphql-js/issues/2203')
   const argumentNodes = node.arguments ?? [];

src/jsutils/__tests__/identityFunc-test.ts

@@ -5,7 +5,7 @@ import { identityFunc } from '../identityFunc';
 
 describe('identityFunc', () => {
   it('returns the first argument it receives', () => {
-    // @ts-expect-error FIXME: TS Conversion
+    // @ts-expect-error (Expects an argument)
     expect(identityFunc()).to.equal(undefined);
     expect(identityFunc(undefined)).to.equal(undefined);
     expect(identityFunc(null)).to.equal(null);

src/jsutils/__tests__/inspect-test.ts

@@ -132,13 +132,13 @@ describe('inspect', () => {
       '{ self: [Circular], deepSelf: { self: [Circular] } }',
     );
 
-    const array = [];
+    const array: any = [];
     array[0] = array;
     array[1] = [array];
 
     expect(inspect(array)).to.equal('[[Circular], [[Circular]]]');
 
-    const mixed = { array: [] };
+    const mixed: any = { array: [] };
     mixed.array[0] = mixed;
 
     expect(inspect(mixed)).to.equal('{ array: [[Circular]] }');
@@ -165,14 +165,21 @@ describe('inspect', () => {
 
     expect(inspect([[new Foo()]])).to.equal('[[[Foo]]]');
 
-    Foo.prototype[Symbol.toStringTag] = 'Bar';
-    expect(inspect([[new Foo()]])).to.equal('[[[Bar]]]');
+    class Foo2 {
+      foo: string;
+
+      [Symbol.toStringTag] = 'Bar';
+
+      constructor() {
+        this.foo = 'bar';
+      }
+    }
+    expect(inspect([[new Foo2()]])).to.equal('[[[Bar]]]');
 
     // eslint-disable-next-line func-names
-    const objectWithoutClassName = new (function () {
-      // eslint-disable-next-line @typescript-eslint/no-invalid-this
+    const objectWithoutClassName = new (function (this: any) {
       this.foo = 1;
-    })();
+    } as any)();
     expect(inspect([[objectWithoutClassName]])).to.equal('[[[Object]]]');
   });
 });

src/jsutils/didYouMean.ts

@@ -12,10 +12,9 @@ export function didYouMean(
   firstArg: string | ReadonlyArray<string>,
   secondArg?: ReadonlyArray<string>,
 ) {
-  const [subMessage, suggestionsArg] =
-    typeof firstArg === 'string'
-      ? [firstArg, secondArg]
-      : [undefined, firstArg];
+  const [subMessage, suggestionsArg] = secondArg
+    ? [firstArg as string, secondArg]
+    : [undefined, firstArg as ReadonlyArray<string>];
 
   let message = ' Did you mean ';
   if (subMessage) {

src/jsutils/inspect.ts

@@ -22,7 +22,7 @@ function formatValue(value: unknown, seenValues: Array<unknown>): string {
 }
 
 function formatObjectValue(
-  value: Object,
+  value: object | null,
   previouslySeenValues: Array<unknown>,
 ): string {
   if (value === null) {
@@ -35,10 +35,8 @@ function formatObjectValue(
 
   const seenValues = [...previouslySeenValues, value];
 
-  // @ts-expect-error FIXME: TS Conversion
-  if (typeof value.toJSON === 'function') {
-    // @ts-expect-error FIXME: TS Conversion
-    const jsonValue = (value.toJSON as () => unknown)();
+  if (isJSONable(value)) {
+    const jsonValue = value.toJSON();
 
     // check for infinite recursion
     if (jsonValue !== value) {
@@ -53,7 +51,11 @@ function formatObjectValue(
   return formatObject(value, seenValues);
 }
 
-function formatObject(object: Object, seenValues: Array<unknown>): string {
+function isJSONable(value: any): value is { toJSON: () => unknown } {
+  return typeof value.toJSON === 'function';
+}
+
+function formatObject(object: object, seenValues: Array<unknown>): string {
   const entries = Object.entries(object);
   if (entries.length === 0) {
     return '{}';
@@ -98,7 +100,7 @@ function formatArray(
   return '[' + items.join(', ') + ']';
 }
 
-function getObjectTag(object: Object): string {
+function getObjectTag(object: object): string {
   const tag = Object.prototype.toString
     .call(object)
     .replace(/^\[object /, '')

src/jsutils/isAsyncIterable.ts

@@ -3,7 +3,7 @@
  * implementing a `Symbol.asyncIterator` method.
  */
 export function isAsyncIterable(
-  maybeAsyncIterable: unknown,
+  maybeAsyncIterable: any,
 ): maybeAsyncIterable is AsyncIterable<unknown> {
   return typeof maybeAsyncIterable?.[Symbol.asyncIterator] === 'function';
 }

src/jsutils/isIterableObject.ts

@@ -15,7 +15,7 @@
  * isIterableObject({ length: 1, 0: 'Alpha' }) // false
  */
 export function isIterableObject(
-  maybeIterable: unknown,
+  maybeIterable: any,
 ): maybeIterable is Iterable<unknown> {
   return (
     typeof maybeIterable === 'object' &&

src/jsutils/isPromise.ts

@@ -2,7 +2,6 @@
  * Returns true if the value acts like a Promise, i.e. has a "then" function,
  * otherwise returns false.
  */
-export function isPromise(value: unknown): value is Promise<unknown> {
-  // eslint-disable-next-line @typescript-eslint/dot-notation
-  return typeof value?.['then'] === 'function';
+export function isPromise(value: any): value is Promise<unknown> {
+  return typeof value?.then === 'function';
 }

src/jsutils/memoize3.ts

@@ -7,7 +7,7 @@ export function memoize3<
   A3 extends object,
   R,
 >(fn: (a1: A1, a2: A2, a3: A3) => R): (a1: A1, a2: A2, a3: A3) => R {
-  let cache0;
+  let cache0: WeakMap<A1, WeakMap<A2, WeakMap<A3, R>>>;
 
   return function memoized(a1, a2, a3) {
     if (cache0 === undefined) {