From e3d23cc40e158ca4f1085a6e4584c78818bac70c Mon Sep 17 00:00:00 2001
From: Anders Hejlsberg <andersh@microsoft.com>
Date: Tue, 24 Sep 2019 06:55:38 -0700
Subject: [PATCH] Add tests

---
 .../recursiveTypeReferences1.ts               | 82 +++++++++++++++++++
 1 file changed, 82 insertions(+)
 create mode 100644 tests/cases/conformance/types/typeRelationships/recursiveTypes/recursiveTypeReferences1.ts

diff --git a/tests/cases/conformance/types/typeRelationships/recursiveTypes/recursiveTypeReferences1.ts b/tests/cases/conformance/types/typeRelationships/recursiveTypes/recursiveTypeReferences1.ts
new file mode 100644
index 00000000000..16e23284963
--- /dev/null
+++ b/tests/cases/conformance/types/typeRelationships/recursiveTypes/recursiveTypeReferences1.ts
@@ -0,0 +1,82 @@
+// @strict: true
+// @declaration: true
+
+type ValueOrArray<T> = T | Array<ValueOrArray<T>>;
+
+const a0: ValueOrArray<number> = 1;
+const a1: ValueOrArray<number> = [1, [2, 3], [4, [5, [6, 7]]]];
+
+type HypertextNode = string | [string, { [key: string]: unknown }, ...HypertextNode[]];
+
+const hypertextNode: HypertextNode =
+    ["div", { id: "parent" },
+        ["div", { id: "first-child" }, "I'm the first child"],
+        ["div", { id: "second-child" }, "I'm the second child"]
+    ];
+
+type Json = string | number | boolean | null | Json[] | { [key: string]: Json };
+
+let data: Json = {
+    caption: "Test",
+    location: { x: 10, y: 20 },
+    values: [true, [10, 20], null]
+};
+
+interface Box<T> { value: T };
+
+type T1 = Box<T1>;
+type T2 = Box<Box<T2>>;
+type T3 = Box<Box<Box<T3>>>;
+
+function f1(t1: T1, t2: T2, t3: T3) {
+    t1 = t2;
+    t1 = t3;
+    t2 = t1;
+    t2 = t3;
+    t3 = t1;
+    t3 = t2;
+}
+
+type Box1 = Box<Box1> | number;
+
+const b10: Box1 = 42;
+const b11: Box1 = { value: 42 };
+const b12: Box1 = { value: { value: { value: 42 }}};
+
+type Box2 = Box<Box2 | number>;
+
+const b20: Box2 = 42;  // Error
+const b21: Box2 = { value: 42 };
+const b22: Box2 = { value: { value: { value: 42 }}};
+
+type RecArray<T> = Array<T | RecArray<T>>;
+
+declare function flat<T>(a: RecArray<T>): Array<T>;
+declare function flat1<T>(a: Array<T | Array<T>>): Array<T>
+declare function flat2<T>(a: Array<T | Array<T | Array<T>>>): Array<T>;
+
+flat([1, [2, [3]]]);  // number[]
+flat([[[0]]]);  // number[]
+flat([[[[[[[[[[[4]]]]]]]]]]]);  // number[]
+flat([1, 'a', [2]]);  // (string | number)[]
+flat([1, [2, 'a']]);  // (string | number)[]
+flat([1, ['a']]);  // Error
+
+flat1([1, [2, [3]]]);  // (number | number[])[]
+flat1([[[0]]]);  // number[][]
+flat1([1, 'a', [2]]);  // (string | number)[]
+flat1([1, [2, 'a']]);  // (string | number)[]
+flat1([1, ['a']]);  // Error
+
+flat2([1, [2, [3]]]);  // number[]
+flat2([[[0]]]);  // number[]
+flat2([1, 'a', [2]]);  // (string | number)[]
+flat2([1, [2, 'a']]);  // (string | number)[]
+flat2([1, ['a']]);  // Error
+
+type T10 = T10[];
+type T11 = readonly T11[];
+type T12 = (T12)[];
+type T13 = T13[] | string;
+type T14 = T14[] & { x: string };
+type T15<X> = X extends string ? T15<X>[] : never;