Add tests

Author: ahejlsberg

tests/cases/conformance/types/tuple/unionsOfTupleTypes1.ts

@@ -0,0 +1,64 @@
+// @strict: true
+
+type T1 = [string, number];
+type T2 = [boolean] | [string, number];
+type T3 = [string, ...number[]];
+type T4 = [boolean] | [string, ...number[]];
+
+type T10 = T1[0];  // string
+type T11 = T1[1];  // number
+type T12 = T1[2];  // undefined
+type T1N = T1[number];  // string | number
+
+type T20 = T2[0];  // string | boolean
+type T21 = T2[1];  // number | undefined
+type T22 = T2[2];  // undefined
+type T2N = T2[number];  // string | number | boolean
+
+type T30 = T3[0];  // string
+type T31 = T3[1];  // number
+type T32 = T3[2];  // number
+type T3N = T3[number];  // string | number
+
+type T40 = T4[0];  // string | boolean
+type T41 = T4[1];  // number | undefined
+type T42 = T4[2];  // number | undefined
+type T4N = T4[number];  // string | number | boolean
+
+function f1(t1: T1, t2: T2, t3: T3, t4: T4, x: number) {
+    let [d10, d11, d12] = t1;  // string, number
+    let [d20, d21, d22] = t2;  // string | boolean, number | undefined
+    let [d30, d31, d32] = t3;  // string, number, number
+    let [d40, d41, d42] = t4;  // string | boolean, number | undefined, number | undefined
+    [d10, d11, d12] = t1;
+    [d20, d21, d22] = t2;
+    [d30, d31, d32] = t3;
+    [d40, d41, d42] = t4;
+    let t10 = t1[0];  // string
+    let t11 = t1[1];  // number
+    let t12 = t1[2];  // undefined
+    let t1x = t1[x];  // string | number
+    let t20 = t2[0];  // string | boolean
+    let t21 = t2[1];  // number | undefined
+    let t22 = t2[2];  // undefined
+    let t2x = t2[x];  // string | number | boolean
+    let t30 = t3[0];  // string
+    let t31 = t3[1];  // number
+    let t32 = t3[2];  // number
+    let t3x = t3[x];  // string | number
+    let t40 = t4[0];  // string | boolean
+    let t41 = t4[1];  // number | undefined
+    let t42 = t4[2];  // number | undefined
+    let t4x = t4[x];  // string | number | boolean
+    t1[1] = 42;
+    t2[1] = 42;
+    t3[1] = 42;
+    t4[1] = 42;
+}
+
+// Repro from #27543
+
+type Unioned = [string] | [string, number];
+const ex: Unioned = ["hi"] as Unioned;
+
+const [x, y] = ex;