Add tests

ahejlsberg · ahejlsberg · commit e54606b7bf6a · 2018-02-08T17:14:52.000-08:00
diff --git a/tests/cases/conformance/types/conditional/conditionalTypes1.ts b/tests/cases/conformance/types/conditional/conditionalTypes1.ts
@@ -226,3 +226,33 @@ type T80 = Eq2<true, true>;  // true
 type T81 = Eq2<true, false>;  // false
 type T82 = Eq2<false, true>;  // false
 type T83 = Eq2<false, false>;  // true
+
+// Repro from #21756
+
+type Foo<T> = T extends string ? boolean : number;
+type Bar<T> = T extends string ? boolean : number;
+const convert = <U>(value: Foo<U>): Bar<U> => value;
+
+type Baz<T> = Foo<T>;
+const convert2 = <T>(value: Foo<T>): Baz<T> => value;
+
+function f31<T>() {
+    type T1 = T extends string ? boolean : number;
+    type T2 = T extends string ? boolean : number;
+    var x: T1;
+    var x: T2;
+}
+
+function f32<T, U>() {
+    type T1 = T & U extends string ? boolean : number;
+    type T2 = Foo<T & U>;
+    var z: T1;
+    var z: T2;  // Error, T2 is distributive, T1 isn't
+}
+
+function f33<T, U>() {
+    type T1 = Foo<T & U>;
+    type T2 = Bar<T & U>;
+    var z: T1;
+    var z: T2;
+}
