diff --git a/src/testRunner/unittests/convertToAsyncFunction.ts b/src/testRunner/unittests/convertToAsyncFunction.ts
index a1e8169e45..186b9059a3 100644
--- a/src/testRunner/unittests/convertToAsyncFunction.ts
+++ b/src/testRunner/unittests/convertToAsyncFunction.ts
@@ -363,6 +363,8 @@ interface Array<T> {}`
             const diagnostics = languageService.getSuggestionDiagnostics(f.path);
             const diagnostic = find(diagnostics, diagnostic => diagnostic.messageText === diagnosticDescription.message);
             assert.exists(diagnostic);
+            assert.equal(diagnostic!.start, context.span.start);
+            assert.equal(diagnostic!.length, context.span.length);
 
             const actions = codefix.getFixes(context);
             const action = find(actions, action => action.description === codeFixDescription.message)!;
@@ -423,6 +425,10 @@ interface Array<T> {}`
         _testConvertToAsyncFunction("convertToAsyncFunction_basic", `
 function [#|f|](): Promise<void>{
     return fetch('https://typescriptlang.org').then(result => { console.log(result) });
+}`);
+    _testConvertToAsyncFunction("convertToAsyncFunction_basicNoReturnTypeAnnotation", `
+function [#|f|]() {
+    return fetch('https://typescriptlang.org').then(result => { console.log(result) });
 }`);
     _testConvertToAsyncFunction("convertToAsyncFunction_basicWithComments", `
 function [#|f|](): Promise<void>{
@@ -436,6 +442,10 @@ function [#|f|](): Promise<void>{
         _testConvertToAsyncFunction("convertToAsyncFunction_ArrowFunction", `
 [#|():Promise<void> => {|]
     return fetch('https://typescriptlang.org').then(result => console.log(result));
+}`);
+    _testConvertToAsyncFunction("convertToAsyncFunction_ArrowFunctionNoAnnotation", `
+[#|() => {|]
+    return fetch('https://typescriptlang.org').then(result => console.log(result));
 }`);
         _testConvertToAsyncFunction("convertToAsyncFunction_Catch", `
 function [#|f|]():Promise<void> {
@@ -1178,6 +1188,12 @@ function [#|f|]() {
     }
 `);
 
+    _testConvertToAsyncFunction("convertToAsyncFunction_simpleFunctionExpression", `
+const [#|foo|] = function () {
+    return fetch('https://typescriptlang.org').then(result => { console.log(result) });
+} 
+`);
+
 
     });
 
diff --git a/tests/baselines/reference/convertToAsyncFunction/convertToAsyncFunction_ArrowFunctionNoAnnotation.js b/tests/baselines/reference/convertToAsyncFunction/convertToAsyncFunction_ArrowFunctionNoAnnotation.js
new file mode 100644
index 0000000000..500d546971
--- /dev/null
+++ b/tests/baselines/reference/convertToAsyncFunction/convertToAsyncFunction_ArrowFunctionNoAnnotation.js
@@ -0,0 +1,11 @@
+// ==ORIGINAL==
+
+/*[#|*/() => {/*|]*/
+    return fetch('https://typescriptlang.org').then(result => console.log(result));
+}
+// ==ASYNC FUNCTION::Convert to async function==
+
+async () => {
+    const result = await fetch('https://typescriptlang.org');
+    return console.log(result);
+}
\ No newline at end of file
diff --git a/tests/baselines/reference/convertToAsyncFunction/convertToAsyncFunction_ArrowFunctionNoAnnotation.ts b/tests/baselines/reference/convertToAsyncFunction/convertToAsyncFunction_ArrowFunctionNoAnnotation.ts
new file mode 100644
index 0000000000..500d546971
--- /dev/null
+++ b/tests/baselines/reference/convertToAsyncFunction/convertToAsyncFunction_ArrowFunctionNoAnnotation.ts
@@ -0,0 +1,11 @@
+// ==ORIGINAL==
+
+/*[#|*/() => {/*|]*/
+    return fetch('https://typescriptlang.org').then(result => console.log(result));
+}
+// ==ASYNC FUNCTION::Convert to async function==
+
+async () => {
+    const result = await fetch('https://typescriptlang.org');
+    return console.log(result);
+}
\ No newline at end of file
diff --git a/tests/baselines/reference/convertToAsyncFunction/convertToAsyncFunction_basicNoReturnTypeAnnotation.js b/tests/baselines/reference/convertToAsyncFunction/convertToAsyncFunction_basicNoReturnTypeAnnotation.js
new file mode 100644
index 0000000000..8aec78c667
--- /dev/null
+++ b/tests/baselines/reference/convertToAsyncFunction/convertToAsyncFunction_basicNoReturnTypeAnnotation.js
@@ -0,0 +1,11 @@
+// ==ORIGINAL==
+
+function /*[#|*/f/*|]*/() {
+    return fetch('https://typescriptlang.org').then(result => { console.log(result) });
+}
+// ==ASYNC FUNCTION::Convert to async function==
+
+async function f() {
+    const result = await fetch('https://typescriptlang.org');
+    console.log(result);
+}
\ No newline at end of file
diff --git a/tests/baselines/reference/convertToAsyncFunction/convertToAsyncFunction_basicNoReturnTypeAnnotation.ts b/tests/baselines/reference/convertToAsyncFunction/convertToAsyncFunction_basicNoReturnTypeAnnotation.ts
new file mode 100644
index 0000000000..8aec78c667
--- /dev/null
+++ b/tests/baselines/reference/convertToAsyncFunction/convertToAsyncFunction_basicNoReturnTypeAnnotation.ts
@@ -0,0 +1,11 @@
+// ==ORIGINAL==
+
+function /*[#|*/f/*|]*/() {
+    return fetch('https://typescriptlang.org').then(result => { console.log(result) });
+}
+// ==ASYNC FUNCTION::Convert to async function==
+
+async function f() {
+    const result = await fetch('https://typescriptlang.org');
+    console.log(result);
+}
\ No newline at end of file
diff --git a/tests/baselines/reference/convertToAsyncFunction/convertToAsyncFunction_simpleFunctionExpression.js b/tests/baselines/reference/convertToAsyncFunction/convertToAsyncFunction_simpleFunctionExpression.js
new file mode 100644
index 0000000000..a92497ca93
--- /dev/null
+++ b/tests/baselines/reference/convertToAsyncFunction/convertToAsyncFunction_simpleFunctionExpression.js
@@ -0,0 +1,12 @@
+// ==ORIGINAL==
+
+const /*[#|*/foo/*|]*/ = function () {
+    return fetch('https://typescriptlang.org').then(result => { console.log(result) });
+} 
+
+// ==ASYNC FUNCTION::Convert to async function==
+
+const foo = async function () {
+    const result = await fetch('https://typescriptlang.org');
+    console.log(result);
+} 
diff --git a/tests/baselines/reference/convertToAsyncFunction/convertToAsyncFunction_simpleFunctionExpression.ts b/tests/baselines/reference/convertToAsyncFunction/convertToAsyncFunction_simpleFunctionExpression.ts
new file mode 100644
index 0000000000..a92497ca93
--- /dev/null
+++ b/tests/baselines/reference/convertToAsyncFunction/convertToAsyncFunction_simpleFunctionExpression.ts
@@ -0,0 +1,12 @@
+// ==ORIGINAL==
+
+const /*[#|*/foo/*|]*/ = function () {
+    return fetch('https://typescriptlang.org').then(result => { console.log(result) });
+} 
+
+// ==ASYNC FUNCTION::Convert to async function==
+
+const foo = async function () {
+    const result = await fetch('https://typescriptlang.org');
+    console.log(result);
+}