TS: Fix strict issues in src/language

src/language/__tests__/lexer-test.ts

@@ -7,6 +7,7 @@ import { inspect } from '../../jsutils/inspect';
 
 import { GraphQLError } from '../../error/GraphQLError';
 
+import type { Token } from '../ast';
 import { Source } from '../source';
 import { TokenKind } from '../tokenKind';
 import { Lexer, isPunctuatorTokenKind } from '../lexer';
@@ -876,7 +877,7 @@ describe('Lexer', () => {
     expect(endToken.next).to.equal(null);
 
     const tokens = [];
-    for (let tok = startToken; tok; tok = tok.next) {
+    for (let tok: Token | null = startToken; tok; tok = tok.next) {
       if (tokens.length) {
         // Tokens are double-linked, prev should point to last seen token.
         expect(tok.prev).to.equal(tokens[tokens.length - 1]);

src/language/__tests__/visitor-test.ts

@@ -3,7 +3,7 @@ import { describe, it } from 'mocha';
 
 import { kitchenSinkQuery } from '../../__testUtils__/kitchenSinkQuery';
 
-import type { ASTNode } from '../ast';
+import type { ASTNode, SelectionSetNode } from '../ast';
 import { isNode } from '../ast';
 import { Kind } from '../kinds';
 import { parse } from '../parser';
@@ -62,7 +62,7 @@ describe('Visitor', () => {
   });
 
   it('validates path argument', () => {
-    const visited = [];
+    const visited: Array<any> = [];
 
     const ast = parse('{ a }', { noLocation: true });
 
@@ -93,7 +93,7 @@ describe('Visitor', () => {
 
   it('validates ancestors argument', () => {
     const ast = parse('{ a }', { noLocation: true });
-    const visitedNodes = [];
+    const visitedNodes: Array<any> = [];
 
     visit(ast, {
       enter(node, key, parent, _path, ancestors) {
@@ -122,7 +122,7 @@ describe('Visitor', () => {
   it('allows editing a node both on enter and on leave', () => {
     const ast = parse('{ a, b, c { a, b, c } }', { noLocation: true });
 
-    let selectionSet;
+    let selectionSet: SelectionSetNode;
 
     const editedAST = visit(ast, {
       OperationDefinition: {
@@ -279,7 +279,7 @@ describe('Visitor', () => {
   });
 
   it('allows skipping a sub-tree', () => {
-    const visited = [];
+    const visited: Array<any> = [];
 
     const ast = parse('{ a, b { x }, c }', { noLocation: true });
     visit(ast, {
@@ -317,7 +317,7 @@ describe('Visitor', () => {
   });
 
   it('allows early exit while visiting', () => {
-    const visited = [];
+    const visited: Array<any> = [];
 
     const ast = parse('{ a, b { x }, c }', { noLocation: true });
     visit(ast, {
@@ -352,7 +352,7 @@ describe('Visitor', () => {
   });
 
   it('allows early exit while leaving', () => {
-    const visited = [];
+    const visited: Array<any> = [];
 
     const ast = parse('{ a, b { x }, c }', { noLocation: true });
     visit(ast, {
@@ -389,7 +389,7 @@ describe('Visitor', () => {
   });
 
   it('allows a named functions visitor API', () => {
-    const visited = [];
+    const visited: Array<any> = [];
 
     const ast = parse('{ a, b { x }, c }', { noLocation: true });
     visit(ast, {
@@ -438,7 +438,7 @@ describe('Visitor', () => {
       },
     });
 
-    const visited = [];
+    const visited: Array<any> = [];
     visit(customAST, {
       enter(node) {
         visited.push(['enter', node.kind, getValue(node)]);
@@ -469,7 +469,7 @@ describe('Visitor', () => {
       noLocation: true,
       allowLegacyFragmentVariables: true,
     });
-    const visited = [];
+    const visited: Array<any> = [];
 
     visit(ast, {
       enter(node) {
@@ -516,8 +516,8 @@ describe('Visitor', () => {
 
   it('visits kitchen sink', () => {
     const ast = parse(kitchenSinkQuery);
-    const visited = [];
-    const argsStack = [];
+    const visited: Array<any> = [];
+    const argsStack: Array<any> = [];
 
     visit(ast, {
       enter(node, key, parent) {
@@ -895,7 +895,7 @@ describe('Visitor', () => {
     // Note: nearly identical to the above test of the same test but
     // using visitInParallel.
     it('allows skipping a sub-tree', () => {
-      const visited = [];
+      const visited: Array<any> = [];
 
       const ast = parse('{ a, b { x }, c }');
       visit(
@@ -938,7 +938,7 @@ describe('Visitor', () => {
     });
 
     it('allows skipping different sub-trees', () => {
-      const visited = [];
+      const visited: Array<any> = [];
 
       const ast = parse('{ a { x }, b { y} }');
       visit(
@@ -1014,7 +1014,7 @@ describe('Visitor', () => {
     // Note: nearly identical to the above test of the same test but
     // using visitInParallel.
     it('allows early exit while visiting', () => {
-      const visited = [];
+      const visited: Array<any> = [];
 
       const ast = parse('{ a, b { x }, c }');
       visit(
@@ -1054,7 +1054,7 @@ describe('Visitor', () => {
     });
 
     it('allows early exit from different points', () => {
-      const visited = [];
+      const visited: Array<any> = [];
 
       const ast = parse('{ a { y }, b { x } }');
       visit(
@@ -1116,7 +1116,7 @@ describe('Visitor', () => {
     // Note: nearly identical to the above test of the same test but
     // using visitInParallel.
     it('allows early exit while leaving', () => {
-      const visited = [];
+      const visited: Array<any> = [];
 
       const ast = parse('{ a, b { x }, c }');
       visit(
@@ -1157,7 +1157,7 @@ describe('Visitor', () => {
     });
 
     it('allows early exit from leaving different points', () => {
-      const visited = [];
+      const visited: Array<any> = [];
 
       const ast = parse('{ a { y }, b { x } }');
       visit(
@@ -1233,7 +1233,7 @@ describe('Visitor', () => {
     });
 
     it('allows for editing on enter', () => {
-      const visited = [];
+      const visited: Array<any> = [];
 
       const ast = parse('{ a, b, c { a, b, c } }', { noLocation: true });
       const editedAST = visit(
@@ -1297,7 +1297,7 @@ describe('Visitor', () => {
     });
 
     it('allows for editing on leave', () => {
-      const visited = [];
+      const visited: Array<any> = [];
 
       const ast = parse('{ a, b, c { a, b, c } }', { noLocation: true });
       const editedAST = visit(

src/language/ast.ts

@@ -124,9 +124,8 @@ export class Token {
 /**
  * @internal
  */
-export function isNode(maybeNode: unknown): maybeNode is ASTNode {
-  // eslint-disable-next-line @typescript-eslint/dot-notation
-  return typeof maybeNode?.['kind'] === 'string';
+export function isNode(maybeNode: any): maybeNode is ASTNode {
+  return typeof maybeNode?.kind === 'string';
 }
 
 /**

src/language/location.ts

@@ -1,3 +1,5 @@
+import { invariant } from '../jsutils/invariant';
+
 import type { Source } from './source';
 
 const LineRegExp = /\r\n|[\n\r]/g;
@@ -19,6 +21,7 @@ export function getLocation(source: Source, position: number): SourceLocation {
   let line = 1;
 
   for (const match of source.body.matchAll(LineRegExp)) {
+    invariant(typeof match.index === 'number');
     if (match.index >= position) {
       break;
     }

src/language/parser.ts

@@ -34,6 +34,8 @@ import type {
   ConstDirectiveNode,
   TypeNode,
   NamedTypeNode,
+  ListTypeNode,
+  NonNullTypeNode,
   TypeSystemDefinitionNode,
   SchemaDefinitionNode,
   OperationTypeDefinitionNode,
@@ -727,8 +729,7 @@ export class Parser {
     if (this.expectOptionalToken(TokenKind.BRACKET_L)) {
       const innerType = this.parseTypeReference();
       this.expectToken(TokenKind.BRACKET_R);
-      type = this.node(start, {
-        // @ts-expect-error FIXME: TS Conversion
+      type = this.node<ListTypeNode>(start, {
         kind: Kind.LIST_TYPE,
         type: innerType,
       });
@@ -737,13 +738,12 @@ export class Parser {
     }
 
     if (this.expectOptionalToken(TokenKind.BANG)) {
-      // @ts-expect-error FIXME: TS Conversion
-      return this.node(start, {
-        // @ts-expect-error FIXME: TS Conversion
+      return this.node<NonNullTypeNode>(start, {
         kind: Kind.NON_NULL_TYPE,
         type,
       });
     }
+
     return type;
   }
 
@@ -1420,7 +1420,7 @@ export class Parser {
   parseDirectiveLocation(): NameNode {
     const start = this._lexer.token;
     const name = this.parseName();
-    if (DirectiveLocation[name.value] !== undefined) {
+    if (Object.prototype.hasOwnProperty.call(DirectiveLocation, name.value)) {
       return name;
     }
     throw this.unexpected(start);

src/language/printer.ts

@@ -1,7 +1,7 @@
 import type { Maybe } from '../jsutils/Maybe';
 
 import type { ASTNode } from './ast';
-
+import type { ASTReducer } from './visitor';
 import { visit } from './visitor';
 import { printBlockString } from './blockString';
 
@@ -15,8 +15,7 @@ export function print(ast: ASTNode): string {
 
 const MAX_LINE_LENGTH = 80;
 
-// TODO: provide better type coverage in future
-const printDocASTReducer: any = {
+const printDocASTReducer: ASTReducer<string> = {
   Name: { leave: (node) => node.value },
   Variable: { leave: (node) => '$' + node.name },
 
@@ -309,15 +308,18 @@ const printDocASTReducer: any = {
  * Given maybeArray, print an empty string if it is null or empty, otherwise
  * print all items together separated by separator if provided
  */
-function join(maybeArray: Maybe<Array<string>>, separator = ''): string {
+function join(
+  maybeArray: Maybe<ReadonlyArray<string | undefined>>,
+  separator = '',
+): string {
   return maybeArray?.filter((x) => x).join(separator) ?? '';
 }
 
 /**
  * Given array, print each item on its own line, wrapped in an
  * indented "{ }" block.
  */
-function block(array: Maybe<Array<string>>): string {
+function block(array: Maybe<ReadonlyArray<string | undefined>>): string {
   return wrap('{\n', indent(join(array, '\n')), '\n}');
 }
 
@@ -338,7 +340,7 @@ function indent(str: string): string {
   return wrap('  ', str.replace(/\n/g, '\n  '));
 }
 
-function hasMultilineItems(maybeArray: Maybe<Array<string>>): boolean {
+function hasMultilineItems(maybeArray: Maybe<ReadonlyArray<string>>): boolean {
   // istanbul ignore next (See: 'https://github.com/graphql/graphql-js/issues/2203')
   return maybeArray?.some((str) => str.includes('\n')) ?? false;
 }