Merge pull request #27573 from uniqueiniquity/alwaysAwait

Always await expression of promise type in return position

Author: uniqueiniquity

src/services/codefixes/convertToAsyncFunction.ts

@@ -465,19 +465,19 @@ namespace ts.codefix {
                         return innerCbBody;
                     }
 
+                    const type = transformer.checker.getTypeAtLocation(func);
+                    const returnType = getLastCallSignature(type, transformer.checker)!.getReturnType();
+                    const rightHandSide = getSynthesizedDeepClone(funcBody);
+                    const possiblyAwaitedRightHandSide = !!transformer.checker.getPromisedTypeOfPromise(returnType) ? createAwait(rightHandSide) : rightHandSide;
                     if (!shouldReturn) {
-                        const type = transformer.checker.getTypeAtLocation(func);
-                        const returnType = getLastCallSignature(type, transformer.checker)!.getReturnType();
-                        const rightHandSide = getSynthesizedDeepClone(funcBody);
-                        const possiblyAwaitedRightHandSide = !!transformer.checker.getPromisedTypeOfPromise(returnType) ? createAwait(rightHandSide) : rightHandSide;
                         const transformedStatement = createTransformedStatement(prevArgName, possiblyAwaitedRightHandSide, transformer);
                         if (prevArgName) {
                             prevArgName.types.push(returnType);
                         }
                         return transformedStatement;
                     }
                     else {
-                        return [createReturn(getSynthesizedDeepClone(funcBody))];
+                        return [createReturn(possiblyAwaitedRightHandSide)];
                     }
                 }
             }

src/testRunner/unittests/convertToAsyncFunction.ts

@@ -1236,6 +1236,13 @@ function [#|f|]() {
 }
 `);
 
+    _testConvertToAsyncFunction("convertToAsyncFunction_callbackReturnsRejectedPromiseInTryBlock", `
+function [#|f|]() {
+    return Promise.resolve(1)
+        .then(x => Promise.reject(x))
+        .catch(err => console.log(err));
+}    
+`);
 
 _testConvertToAsyncFunction("convertToAsyncFunction_nestedPromises", `
 function [#|f|]() {

tests/baselines/reference/convertToAsyncFunction/convertToAsyncFunction_callbackReturnsPromiseLastInChain.js

@@ -8,5 +8,5 @@ function /*[#|*/f/*|]*/() {
 
 async function f() {
     const s = await fetch('https://typescriptlang.org');
-    return Promise.resolve(s.statusText.length);
+    return await Promise.resolve(s.statusText.length);
 }

tests/baselines/reference/convertToAsyncFunction/convertToAsyncFunction_callbackReturnsPromiseLastInChain.ts

@@ -8,5 +8,5 @@ function /*[#|*/f/*|]*/() {
 
 async function f() {
     const s = await fetch('https://typescriptlang.org');
-    return Promise.resolve(s.statusText.length);
+    return await Promise.resolve(s.statusText.length);
 }

tests/baselines/reference/convertToAsyncFunction/convertToAsyncFunction_callbackReturnsRejectedPromiseInTryBlock.js

@@ -0,0 +1,19 @@
+// ==ORIGINAL==
+
+function /*[#|*/f/*|]*/() {
+    return Promise.resolve(1)
+        .then(x => Promise.reject(x))
+        .catch(err => console.log(err));
+}    
+
+// ==ASYNC FUNCTION::Convert to async function==
+
+async function f() {
+    try {
+        const x = await Promise.resolve(1);
+        return await Promise.reject(x);
+    }
+    catch (err) {
+        return console.log(err);
+    }
+}    

tests/baselines/reference/convertToAsyncFunction/convertToAsyncFunction_callbackReturnsRejectedPromiseInTryBlock.ts

@@ -0,0 +1,19 @@
+// ==ORIGINAL==
+
+function /*[#|*/f/*|]*/() {
+    return Promise.resolve(1)
+        .then(x => Promise.reject(x))
+        .catch(err => console.log(err));
+}    
+
+// ==ASYNC FUNCTION::Convert to async function==
+
+async function f() {
+    try {
+        const x = await Promise.resolve(1);
+        return await Promise.reject(x);
+    }
+    catch (err) {
+        return console.log(err);
+    }
+}    

tests/baselines/reference/convertToAsyncFunction/convertToAsyncFunction_nestedPromises.js

@@ -9,5 +9,5 @@ function /*[#|*/f/*|]*/() {
 async function f() {
     const x = await fetch('https://typescriptlang.org');
     const y = await Promise.resolve(3);
-    return Promise.resolve(x.statusText.length + y);
+    return await Promise.resolve(x.statusText.length + y);
 }

tests/baselines/reference/convertToAsyncFunction/convertToAsyncFunction_nestedPromises.ts

@@ -9,5 +9,5 @@ function /*[#|*/f/*|]*/() {
 async function f() {
     const x = await fetch('https://typescriptlang.org');
     const y = await Promise.resolve(3);
-    return Promise.resolve(x.statusText.length + y);
+    return await Promise.resolve(x.statusText.length + y);
 }