From 307822396425a5d1996691d773a4145ecb43781e Mon Sep 17 00:00:00 2001
From: Jack Bates <jack@nottheoilrig.com>
Date: Thu, 26 Sep 2019 16:04:39 -0700
Subject: [PATCH] Add tests

---
 tests/baselines/reference/arrayFlatMap.js      |  8 ++++++++
 tests/baselines/reference/arrayFlatMap.symbols | 11 +++++++++++
 tests/baselines/reference/arrayFlatMap.types   | 17 +++++++++++++++++
 tests/cases/compiler/arrayFlatMap.ts           |  5 +++++
 4 files changed, 41 insertions(+)

diff --git a/tests/baselines/reference/arrayFlatMap.js b/tests/baselines/reference/arrayFlatMap.js
index 3c35cedc1f3be..0344776d9c245 100644
--- a/tests/baselines/reference/arrayFlatMap.js
+++ b/tests/baselines/reference/arrayFlatMap.js
@@ -3,6 +3,11 @@ const array: number[] = [];
 const readonlyArray: ReadonlyArray<number> = [];
 array.flatMap((): ReadonlyArray<number> => []); // ok
 readonlyArray.flatMap((): ReadonlyArray<number> => []); // ok
+
+// #19535
+
+const [x] = [""].flatMap(undefined as () => string[] | string[][]);
+x == "";
 
 
 //// [arrayFlatMap.js]
@@ -10,3 +15,6 @@ var array = [];
 var readonlyArray = [];
 array.flatMap(function () { return []; }); // ok
 readonlyArray.flatMap(function () { return []; }); // ok
+// #19535
+var x = [""].flatMap(undefined)[0];
+x == "";
diff --git a/tests/baselines/reference/arrayFlatMap.symbols b/tests/baselines/reference/arrayFlatMap.symbols
index b3a8d55721acd..2c08f13dc12d3 100644
--- a/tests/baselines/reference/arrayFlatMap.symbols
+++ b/tests/baselines/reference/arrayFlatMap.symbols
@@ -18,3 +18,14 @@ readonlyArray.flatMap((): ReadonlyArray<number> => []); // ok
 >flatMap : Symbol(ReadonlyArray.flatMap, Decl(lib.es2019.array.d.ts, --, --))
 >ReadonlyArray : Symbol(ReadonlyArray, Decl(lib.es5.d.ts, --, --), Decl(lib.es2015.core.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2016.array.include.d.ts, --, --), Decl(lib.es2019.array.d.ts, --, --))
 
+// #19535
+
+const [x] = [""].flatMap(undefined as () => string[] | string[][]);
+>x : Symbol(x, Decl(arrayFlatMap.ts, 7, 7))
+>[""].flatMap : Symbol(Array.flatMap, Decl(lib.es2019.array.d.ts, --, --))
+>flatMap : Symbol(Array.flatMap, Decl(lib.es2019.array.d.ts, --, --))
+>undefined : Symbol(undefined)
+
+x == "";
+>x : Symbol(x, Decl(arrayFlatMap.ts, 7, 7))
+
diff --git a/tests/baselines/reference/arrayFlatMap.types b/tests/baselines/reference/arrayFlatMap.types
index 3f1e3f863ded1..10a9931a70d71 100644
--- a/tests/baselines/reference/arrayFlatMap.types
+++ b/tests/baselines/reference/arrayFlatMap.types
@@ -23,3 +23,20 @@ readonlyArray.flatMap((): ReadonlyArray<number> => []); // ok
 >(): ReadonlyArray<number> => [] : () => readonly number[]
 >[] : undefined[]
 
+// #19535
+
+const [x] = [""].flatMap(undefined as () => string[] | string[][]);
+>x : string | string[]
+>[""].flatMap(undefined as () => string[] | string[][]) : (string | string[])[]
+>[""].flatMap : <U, This = undefined>(callback: (this: This, value: string, index: number, array: string[]) => U, thisArg?: This) => (U extends readonly (infer V)[] ? V : U)[]
+>[""] : string[]
+>"" : ""
+>flatMap : <U, This = undefined>(callback: (this: This, value: string, index: number, array: string[]) => U, thisArg?: This) => (U extends readonly (infer V)[] ? V : U)[]
+>undefined as () => string[] | string[][] : () => string[] | string[][]
+>undefined : undefined
+
+x == "";
+>x == "" : boolean
+>x : string | string[]
+>"" : ""
+
diff --git a/tests/cases/compiler/arrayFlatMap.ts b/tests/cases/compiler/arrayFlatMap.ts
index 98f84e7877363..a02998b9a607f 100644
--- a/tests/cases/compiler/arrayFlatMap.ts
+++ b/tests/cases/compiler/arrayFlatMap.ts
@@ -4,3 +4,8 @@ const array: number[] = [];
 const readonlyArray: ReadonlyArray<number> = [];
 array.flatMap((): ReadonlyArray<number> => []); // ok
 readonlyArray.flatMap((): ReadonlyArray<number> => []); // ok
+
+// #19535
+
+const [x] = [""].flatMap(undefined as () => string[] | string[][]);
+x == "";