Add tests

Author: jablko

tests/baselines/reference/promiseType.js

@@ -217,6 +217,11 @@ const pc6 = p.then(() => Promise.reject("1"), () => {});
 const pc7 = p.then(() => Promise.reject("1"), () => {throw 1});
 const pc8 = p.then(() => Promise.reject("1"), () => Promise.resolve(1));
 const pc9 = p.then(() => Promise.reject("1"), () => Promise.reject(1));
+
+// #30390
+
+declare function f(): Promise<number> | string;
+p.then(f);
 
 
 //// [promiseType.js]
@@ -440,3 +445,4 @@ const pc6 = p.then(() => Promise.reject("1"), () => { });
 const pc7 = p.then(() => Promise.reject("1"), () => { throw 1; });
 const pc8 = p.then(() => Promise.reject("1"), () => Promise.resolve(1));
 const pc9 = p.then(() => Promise.reject("1"), () => Promise.reject(1));
+p.then(f);

tests/baselines/reference/promiseType.symbols

@@ -1089,3 +1089,15 @@ const pc9 = p.then(() => Promise.reject("1"), () => Promise.reject(1));
 >Promise : Symbol(Promise, Decl(lib.es5.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.promise.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --))
 >reject : Symbol(PromiseConstructor.reject, Decl(lib.es2015.promise.d.ts, --, --))
 
+// #30390
+
+declare function f(): Promise<number> | string;
+>f : Symbol(f, Decl(promiseType.ts, 217, 71))
+>Promise : Symbol(Promise, Decl(lib.es5.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.promise.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --))
+
+p.then(f);
+>p.then : Symbol(Promise.then, Decl(lib.es5.d.ts, --, --))
+>p : Symbol(p, Decl(promiseType.ts, 0, 11))
+>then : Symbol(Promise.then, Decl(lib.es5.d.ts, --, --))
+>f : Symbol(f, Decl(promiseType.ts, 217, 71))
+

tests/baselines/reference/promiseType.types

@@ -1583,3 +1583,15 @@ const pc9 = p.then(() => Promise.reject("1"), () => Promise.reject(1));
 >reject : <T = never>(reason?: any) => Promise<T>
 >1 : 1
 
+// #30390
+
+declare function f(): Promise<number> | string;
+>f : () => string | Promise<number>
+
+p.then(f);
+>p.then(f) : Promise<string | number>
+>p.then : <TResult1 = boolean, TResult2 = never>(onfulfilled?: (value: boolean) => TResult1, onrejected?: (reason: any) => TResult2) => Promise<(TResult1 extends PromiseLike<infer UResult1> ? UResult1 : TResult1) | (TResult2 extends PromiseLike<infer UResult2> ? UResult2 : TResult2)>
+>p : Promise<boolean>
+>then : <TResult1 = boolean, TResult2 = never>(onfulfilled?: (value: boolean) => TResult1, onrejected?: (reason: any) => TResult2) => Promise<(TResult1 extends PromiseLike<infer UResult1> ? UResult1 : TResult1) | (TResult2 extends PromiseLike<infer UResult2> ? UResult2 : TResult2)>
+>f : () => string | Promise<number>
+

tests/cases/compiler/promiseType.ts

@@ -217,3 +217,8 @@ const pc6 = p.then(() => Promise.reject("1"), () => {});
 const pc7 = p.then(() => Promise.reject("1"), () => {throw 1});
 const pc8 = p.then(() => Promise.reject("1"), () => Promise.resolve(1));
 const pc9 = p.then(() => Promise.reject("1"), () => Promise.reject(1));
+
+// #30390
+
+declare function f(): Promise<number> | string;
+p.then(f);