From bb1e01f637f93d0a91a96a52bf689f40d98e5622 Mon Sep 17 00:00:00 2001
From: Sam Verschueren <sam.verschueren@gmail.com>
Date: Wed, 5 Sep 2018 21:00:31 +0200
Subject: [PATCH] Support top-level await - fixes #1 (#4)

---
 readme.md                                            | 12 ++++++++++++
 source/lib/compiler.ts                               |  7 ++++++-
 source/test/fixtures/top-level-await/index.d.ts      |  6 ++++++
 source/test/fixtures/top-level-await/index.js        |  3 +++
 source/test/fixtures/top-level-await/index.test-d.ts |  5 +++++
 source/test/fixtures/top-level-await/package.json    |  7 +++++++
 source/test/test.ts                                  |  6 ++++++
 7 files changed, 45 insertions(+), 1 deletion(-)
 create mode 100644 source/test/fixtures/top-level-await/index.d.ts
 create mode 100644 source/test/fixtures/top-level-await/index.js
 create mode 100644 source/test/fixtures/top-level-await/index.test-d.ts
 create mode 100644 source/test/fixtures/top-level-await/package.json

diff --git a/readme.md b/readme.md
index 74362cc6..fe249e30 100644
--- a/readme.md
+++ b/readme.md
@@ -61,6 +61,18 @@ If we don't change the test file and we run the `tsd-check` command again, the t
 
 <img src="screenshot.png" width="1330">
 
+### Top-level `await`
+
+If your method returns a `Promise`, you can use top-level `await` to resolve the value instead of wrapping it in an `async` [IIFE](https://developer.mozilla.org/en-US/docs/Glossary/IIFE).
+
+```ts
+import {expectType} from 'tsd-check';
+import concat from '.';
+
+expectType<Promise<string>>(concat('foo', 'bar'));
+
+expectType<string>(await concat('foo', 'bar'));
+```
 
 
 ## Assertions
diff --git a/source/lib/compiler.ts b/source/lib/compiler.ts
index d3779f22..57c23af9 100644
--- a/source/lib/compiler.ts
+++ b/source/lib/compiler.ts
@@ -2,6 +2,11 @@ import * as path from 'path';
 import {createProgram, getPreEmitDiagnostics, ScriptTarget, ModuleResolutionKind, flattenDiagnosticMessageText} from 'typescript';
 import {Diagnostic, Context} from './interfaces';
 
+// List of diagnostic codes that should be ignored
+const ignoredDiagnostics = new Set<number>([
+	1308 // Support top-level `await`
+]);
+
 const loadConfig = () => {
 	return {
 		moduleResolution: ModuleResolutionKind.NodeJs,
@@ -28,7 +33,7 @@ export const getDiagnostics = (context: Context): Diagnostic[] => {
 	const result: Diagnostic[] = [];
 
 	for (const diagnostic of diagnostics) {
-		if (!diagnostic.file) {
+		if (!diagnostic.file || ignoredDiagnostics.has(diagnostic.code)) {
 			continue;
 		}
 
diff --git a/source/test/fixtures/top-level-await/index.d.ts b/source/test/fixtures/top-level-await/index.d.ts
new file mode 100644
index 00000000..cc34cfaa
--- /dev/null
+++ b/source/test/fixtures/top-level-await/index.d.ts
@@ -0,0 +1,6 @@
+declare const one: {
+	(foo: string, bar: string): Promise<string>;
+	(foo: number, bar: number): Promise<number>;
+};
+
+export default one;
diff --git a/source/test/fixtures/top-level-await/index.js b/source/test/fixtures/top-level-await/index.js
new file mode 100644
index 00000000..f17717f5
--- /dev/null
+++ b/source/test/fixtures/top-level-await/index.js
@@ -0,0 +1,3 @@
+module.exports.default = (foo, bar) => {
+	return foo + bar;
+};
diff --git a/source/test/fixtures/top-level-await/index.test-d.ts b/source/test/fixtures/top-level-await/index.test-d.ts
new file mode 100644
index 00000000..db17fe37
--- /dev/null
+++ b/source/test/fixtures/top-level-await/index.test-d.ts
@@ -0,0 +1,5 @@
+import {expectType} from '../../..';
+import one from '.';
+
+expectType<string>(await one('foo', 'bar'));
+expectType<number>(await one(1, 2));
diff --git a/source/test/fixtures/top-level-await/package.json b/source/test/fixtures/top-level-await/package.json
new file mode 100644
index 00000000..06ea168a
--- /dev/null
+++ b/source/test/fixtures/top-level-await/package.json
@@ -0,0 +1,7 @@
+{
+	"name": "foo",
+	"files": [
+		"index.js",
+		"index.d.ts"
+	]
+}
diff --git a/source/test/test.ts b/source/test/test.ts
index 87017646..ab84f55e 100644
--- a/source/test/test.ts
+++ b/source/test/test.ts
@@ -36,3 +36,9 @@ test('return no diagnostics', async t => {
 
 	t.true(diagnostics.length === 0);
 });
+
+test('support top-level await', async t => {
+	const diagnostics = await m({cwd: path.join(__dirname, 'fixtures/top-level-await')});
+
+	t.true(diagnostics.length === 0);
+});