[New Rule] add noAsyncWithoutAwait rule

src/rules/code-examples/noAsyncWithoutAwait.examples.ts

@@ -22,7 +22,7 @@ export const codeExamples = [
         config: Lint.Utils.dedent`
             "rules": { "no-async-without-await": true }
         `,
-        description: "Do not use the async in case it is not actually needed",
+        description: "Do not use the async keyword in case it is not actually needed",
         fail: Lint.Utils.dedent`
             async function f() {
                 fetch();

src/rules/noAsyncWithoutAwaitRule.ts

@@ -20,9 +20,11 @@ import * as Lint from "../index";
 import { codeExamples } from "./code-examples/noAsyncWithoutAwait.examples";
 
 export class Rule extends Lint.Rules.AbstractRule {
+    public static FAILURE_STRING = "Functions marked async must contain an await statement.";
+
     public static metadata: Lint.IRuleMetadata = {
         codeExamples,
-        description: "Do not write async functions that do not have an await statement in them",
+        description: Rule.FAILURE_STRING,
         hasFix: false,
         optionExamples: [true],
         options: null,
@@ -33,8 +35,6 @@ export class Rule extends Lint.Rules.AbstractRule {
         typescriptOnly: false,
     };
 
-    public static FAILURE_STRING = "Async functions with no await are not allowed.";
-
     public apply(sourceFile: ts.SourceFile): Lint.RuleFailure[] {
         return this.applyWithWalker(new Walk(sourceFile, this.getOptions()));
     }
@@ -57,7 +57,7 @@ class Walk extends Lint.RuleWalker {
     }
 
     private isAsyncFunction(node: ts.Node): boolean {
-        return Boolean(this.getAsyncModifier(node));
+        return this.getAsyncModifier(node) !== undefined;
     }
 
     private getAsyncModifier(node: ts.Node) {
@@ -72,7 +72,7 @@ class Walk extends Lint.RuleWalker {
         return node.kind === ts.SyntaxKind.AwaitKeyword;
     }
 
-    private functionBlockHasAwait(node: ts.Node) {
+    private functionBlockHasAwait(node: ts.Node): boolean {
         if (this.isAwait(node)) {
             return true;
         }
@@ -83,7 +83,7 @@ class Walk extends Lint.RuleWalker {
             return false;
         }
 
-        const awaitInChildren: boolean[] = node.getChildren()
+        const awaitInChildren = node.getChildren()
             .map((functionBlockNode: ts.Node) => this.functionBlockHasAwait(functionBlockNode));
         return awaitInChildren.some(Boolean);
     }

src/runner.ts

@@ -156,8 +156,8 @@ async function runWorker(options: Options, logger: Logger): Promise<Status> {
     return options.force || errorCount === 0 ? Status.Ok : Status.LintError;
 }
 
-// tslint:disable-next-line:no-async-without-await
-async function runLinter(options: Options, logger: Logger): Promise<LintResult> {
+// tslint:disable-next-line:promise-function-async
+function runLinter(options: Options, logger: Logger): Promise<LintResult> {
     const { files, program } = resolveFilesAndProgram(options, logger);
     // if type checking, run the type checker
     if (program && options.typeCheck) {

test/rules/no-async-without-await/test.ts.lint

@@ -23,7 +23,7 @@ async function a(){
 }
 
 async function a(){
-~~~~~ [Async functions with no await are not allowed.]
+~~~~~ [Functions marked async must contain an await statement.]
    let b = 1;
    async function f() {
         await fetch();
@@ -33,24 +33,24 @@ async function a(){
 function a(){
    let b = 1;
    async function f() {
-   ~~~~~ [Async functions with no await are not allowed.]
+   ~~~~~ [Functions marked async must contain an await statement.]
         fetch();
    };
 }
 
 const a = async () => {
-          ~~~~~ [Async functions with no await are not allowed.]
+          ~~~~~ [Functions marked async must contain an await statement.]
    let b = 1;
    console.log(b);
 }
 
 
 const a = async () => 1;
-          ~~~~~ [Async functions with no await are not allowed.]
+          ~~~~~ [Functions marked async must contain an await statement.]
 
 class A {
     async b() {
-    ~~~~~ [Async functions with no await are not allowed.]
+    ~~~~~ [Functions marked async must contain an await statement.]
         console.log(1);
     }
 }
@@ -65,10 +65,10 @@ async () => {
     await a();
     class A {
         async b() {
-        ~~~~~ [Async functions with no await are not allowed.]
+        ~~~~~ [Functions marked async must contain an await statement.]
             console.log(1);
         }
     }
 };
 
-[0]: Async functions with no await are not allowed.
+[0]: Functions marked async must contain an await statement.