1 files changed, 78 insertions, 0 deletions
diff --git a/test/test-types-compilation.ts b/test/test-types-compilation.ts
new file mode 100644
index 0000000..25c51cc
--- /dev/null
+++ b/test/test-types-compilation.ts
@@ -0,0 +1,78 @@
+/* eslint-disable @typescript-eslint/ban-ts-comment, @typescript-eslint/no-unused-vars */
+
+import nitt from '..';
+
+interface SomeEventData {
+	name: string;
+}
+
+const emitter = nitt<{
+	foo: string;
+	someEvent: SomeEventData;
+	bar?: number;
+}>();
+
+const barHandler = (x?: number) => {};
+const fooHandler = (x: string) => {};
+const wildcardHandler = (
+	_type: 'foo' | 'bar' | 'someEvent',
+	_event: string | SomeEventData | number | undefined
+) => {};
+
+/*
+ * Check that 'on' args are inferred correctly
+ */
+{
+	// @ts-expect-error
+	emitter.on('foo', barHandler);
+	emitter.on('foo', fooHandler);
+
+	emitter.on('bar', barHandler);
+	// @ts-expect-error
+	emitter.on('bar', fooHandler);
+
+	emitter.on('*', wildcardHandler);
+	// fooHandler is ok, because ('foo' | 'bar' | 'someEvent') extends string
+	emitter.on('*', fooHandler);
+	// @ts-expect-error
+	emitter.on('*', barHandler);
+}
+
+/*
+ * Check that 'off' args are inferred correctly
+ */
+{
+	// @ts-expect-error
+	emitter.off('foo', barHandler);
+	emitter.off('foo', fooHandler);
+
+	emitter.off('bar', barHandler);
+	// @ts-expect-error
+	emitter.off('bar', fooHandler);
+
+	emitter.off('*', wildcardHandler);
+	// fooHandler is ok, because ('foo' | 'bar' | 'someEvent') extends string
+	emitter.off('*', fooHandler);
+	// @ts-expect-error
+	emitter.off('*', barHandler);
+}
+
+/*
+ * Check that 'emit' args are inferred correctly
+ */
+{
+	// @ts-expect-error
+	emitter.emit('someEvent', 'NOT VALID');
+	emitter.emit('someEvent', { name: 'jack' });
+
+	// @ts-expect-error
+	emitter.emit('foo');
+	// @ts-expect-error
+	emitter.emit('foo', 1);
+	emitter.emit('foo', 'string');
+
+	emitter.emit('bar');
+	emitter.emit('bar', 1);
+	// @ts-expect-error
+	emitter.emit('bar', 'string');
+}