Compiler test case for usage of contextual rest parameter

Author: sheetalkamat

tests/baselines/reference/contextuallyTypingRestParameters.errors.txt

@@ -0,0 +1,16 @@
+tests/cases/compiler/contextuallyTypingRestParameters.ts(3,9): error TS2323: Type 'string[]' is not assignable to type 'string'.
+tests/cases/compiler/contextuallyTypingRestParameters.ts(5,9): error TS2323: Type 'string[]' is not assignable to type 'string'.
+
+
+==== tests/cases/compiler/contextuallyTypingRestParameters.ts (2 errors) ====
+    var x: (...y: string[]) => void = function (.../*3*/y) { 
+        var t = y; 
+        var x2: string = t; // This should be error
+            ~~
+!!! error TS2323: Type 'string[]' is not assignable to type 'string'.
+        var x3: string[] = t; // No error
+        var y2: string = y; // This should be error
+            ~~
+!!! error TS2323: Type 'string[]' is not assignable to type 'string'.
+        var y3: string[] = y; // No error
+    };

tests/baselines/reference/contextuallyTypingRestParameters.js

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+//// [contextuallyTypingRestParameters.ts]
+var x: (...y: string[]) => void = function (.../*3*/y) { 
+    var t = y; 
+    var x2: string = t; // This should be error
+    var x3: string[] = t; // No error
+    var y2: string = y; // This should be error
+    var y3: string[] = y; // No error
+};
+
+//// [contextuallyTypingRestParameters.js]
+var x = function () {
+    var y = [];
+    for (var _i = 0; _i < arguments.length; _i++) {
+        y[_i - 0] = arguments[_i];
+    }
+    var t = y;
+    var x2 = t; // This should be error
+    var x3 = t; // No error
+    var y2 = y; // This should be error
+    var y3 = y; // No error
+};

tests/cases/compiler/contextuallyTypingRestParameters.ts

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+var x: (...y: string[]) => void = function (.../*3*/y) { 
+    var t = y; 
+    var x2: string = t; // This should be error
+    var x3: string[] = t; // No error
+    var y2: string = y; // This should be error
+    var y3: string[] = y; // No error
+};