convertToAsyncFunction: Disable for .then with both fulfillment and rejection handlers

src/services/suggestionDiagnostics.ts

@@ -156,7 +156,18 @@ namespace ts {
     }
 
     function isPromiseHandler(node: Node): node is CallExpression {
-        return isCallExpression(node) && (hasPropertyAccessExpressionWithName(node, "then") || hasPropertyAccessExpressionWithName(node, "catch"));
+        return isCallExpression(node) && (
+            hasPropertyAccessExpressionWithName(node, "then") && hasSupportedNumberOfArguments(node) ||
+            hasPropertyAccessExpressionWithName(node, "catch"));
+    }
+
+    function hasSupportedNumberOfArguments(node: CallExpression) {
+        if (node.arguments.length > 2) return false;
+        if (node.arguments.length < 2) return true;
+        return some(node.arguments, arg => {
+            return arg.kind === SyntaxKind.NullKeyword ||
+                isIdentifier(arg) && arg.text === "undefined";
+        });
     }
 
     // should be kept up to date with getTransformationBody in convertToAsyncFunction.ts

src/testRunner/unittests/services/convertToAsyncFunction.ts

@@ -558,13 +558,13 @@ function [#|f|]():void{
 }
 `
         );
-        _testConvertToAsyncFunction("convertToAsyncFunction_Rej", `
+        _testConvertToAsyncFunctionFailed("convertToAsyncFunction_Rej", `
 function [#|f|]():Promise<void> {
     return fetch('https://typescriptlang.org').then(result => { console.log(result); }, rejection => { console.log("rejected:", rejection); });
 }
 `
         );
-        _testConvertToAsyncFunction("convertToAsyncFunction_RejRef", `
+        _testConvertToAsyncFunctionFailed("convertToAsyncFunction_RejRef", `
 function [#|f|]():Promise<void> {
     return fetch('https://typescriptlang.org').then(res, rej);
 }
@@ -576,7 +576,7 @@ function rej(err){
 }
 `
         );
-        _testConvertToAsyncFunction("convertToAsyncFunction_RejNoBrackets", `
+        _testConvertToAsyncFunctionFailed("convertToAsyncFunction_RejNoBrackets", `
 function [#|f|]():Promise<void> {
     return fetch('https://typescriptlang.org').then(result => console.log(result), rejection => console.log("rejected:", rejection));
 }
@@ -1238,7 +1238,7 @@ function [#|f|]() {
 }
 `);
 
-        _testConvertToAsyncFunction("convertToAsyncFunction_ResRejNoArgsArrow", `
+        _testConvertToAsyncFunctionFailed("convertToAsyncFunction_ResRejNoArgsArrow", `
     function [#|f|]() {
         return Promise.resolve().then(() => 1, () => "a");
     }
@@ -1436,5 +1436,10 @@ function [#|get|]() {
         .catch<APIResponse<{ email: string }>>(() => ({ success: false }));
 }
 `);
+
+        _testConvertToAsyncFunctionFailed("convertToAsyncFunction_threeArguments", `
+function [#|f|]() {
+    return Promise.resolve().then(undefined, undefined, () => 1);
+}`);
     });
 }