Add more test coverage for unusedParameterInLambda

tests/cases/fourslash/unusedParameterInLambda1.ts

@@ -3,11 +3,12 @@
 // @noUnusedLocals: true
 // @noUnusedParameters: true
 //// function f1() {
-////     [|return (x:number) => {}|]
+////     [|return /*~a*/(/*~b*/x/*~c*/:/*~d*/number/*~e*/)/*~f*/ => /*~g*/{/*~h*/}/*~i*/|]
 //// }
 
+// In a perfect world, /*~f*/ and /*~h*/ would probably be retained.
 verify.codeFix({
     description: "Remove declaration for: 'x'",
     index: 0,
-    newRangeContent: "return () => {}",
+    newRangeContent: "return /*~a*/() => /*~g*/ { }/*~i*/",
 });

tests/cases/fourslash/unusedParameterInLambda2.ts

@@ -0,0 +1,14 @@
+/// <reference path='fourslash.ts' />
+
+// @noUnusedLocals: true
+// @noUnusedParameters: true
+//// function f1() {
+////     [|return /*~a*/x/*~b*/ /*~c*/=>/*~d*/ {/*~e*/}/*~f*/|]
+//// }
+
+// In a perfect world, /*~c*/ and /*~e*/ would probably be retained.
+verify.codeFix({
+    description: "Remove declaration for: 'x'",
+    index: 0,
+    newRangeContent: "return /*~a*/() => /*~d*/ { }/*~f*/",
+});

tests/cases/fourslash/unusedParameterInLambda3.ts

@@ -0,0 +1,14 @@
+/// <reference path='fourslash.ts' />
+
+// @noUnusedLocals: true
+// @noUnusedParameters: true
+//// function f1() {
+////     [|return /*~a*/(/*~b*/x/*~c*/,/*~d*/y/*~e*/)/*~f*/ => /*~g*/x/*~h*/|]
+//// }
+
+// In a perfect world, /*~c*/ would probably be retained, rather than /*~e*/.
+verify.codeFix({
+    description: "Remove declaration for: 'y'",
+    index: 0,
+    newRangeContent: "return /*~a*/(/*~b*/x/*~e*/)/*~f*/ => /*~g*/x/*~h*/",
+});

tests/cases/fourslash/unusedParameterInLambda4.ts

@@ -0,0 +1,13 @@
+/// <reference path='fourslash.ts' />
+
+// @noUnusedLocals: true
+// @noUnusedParameters: true
+//// function f1() {
+////     [|return /*~a*/(/*~b*/x/*~c*/,/*~d*/y/*~e*/)/*~f*/ => /*~g*/y/*~h*/|]
+//// }
+
+verify.codeFix({
+    description: "Remove declaration for: 'x'",
+    index: 0,
+    newRangeContent: "return /*~a*/(/*~d*/y/*~e*/)/*~f*/ => /*~g*/y/*~h*/",
+});