From 5bea1bf9b4412ea4044a099e1be164cd126d56b5 Mon Sep 17 00:00:00 2001
From: thepaperpilot <thepaperpilot@gmail.com>
Date: Mon, 26 Sep 2022 18:41:10 -0500
Subject: [PATCH] Fix isFunction typing

---
 src/features/boards/board.ts |  4 ++--
 src/util/common.ts           |  7 ++++---
 tests/util/common.test.ts    | 20 +++++++++++---------
 3 files changed, 17 insertions(+), 14 deletions(-)

diff --git a/src/features/boards/board.ts b/src/features/boards/board.ts
index 4c2cef5..4743370 100644
--- a/src/features/boards/board.ts
+++ b/src/features/boards/board.ts
@@ -10,7 +10,7 @@ import {
 } from "features/feature";
 import { globalBus } from "game/events";
 import type { Persistent, State } from "game/persistence";
-import { persistent, PersistentState } from "game/persistence";
+import { persistent } from "game/persistence";
 import type { Unsubscribe } from "nanoevents";
 import { isFunction } from "util/common";
 import type {
@@ -336,7 +336,7 @@ export function createBoard<T extends BoardOptions>(
 }
 
 export function getNodeProperty<T>(property: NodeComputable<T>, node: BoardNode): T {
-    return isFunction(property) ? property(node) : unref(property);
+    return isFunction<T, [BoardNode], Computable<T>>(property) ? property(node) : unref(property);
 }
 
 export function getUniqueNodeID(board: GenericBoard): number {
diff --git a/src/util/common.ts b/src/util/common.ts
index b2ac8f1..d7560dd 100644
--- a/src/util/common.ts
+++ b/src/util/common.ts
@@ -12,9 +12,10 @@ export function camelToTitle(camel: string): string {
     return title;
 }
 
-// eslint-disable-next-line @typescript-eslint/ban-types
-export function isFunction(func: unknown): func is Function {
-    return typeof func === "function";
+export function isFunction<T, S extends ReadonlyArray<unknown>, R>(
+    functionOrValue: ((...args: S) => T) | R
+): functionOrValue is (...args: S) => T {
+    return typeof functionOrValue === "function";
 }
 
 export enum Direction {
diff --git a/tests/util/common.test.ts b/tests/util/common.test.ts
index abd1d00..619810f 100644
--- a/tests/util/common.test.ts
+++ b/tests/util/common.test.ts
@@ -13,13 +13,15 @@ describe("isFunction", () => {
     test("Given function returns true", () => expect(isFunction(vi.fn())).toBe(true));
 
     // Go through all primitives and basic types
-    test("Given a string returns false", () => expect(isFunction("test")).toBe(false));
-    test("Given a number returns false", () => expect(isFunction(10)).toBe(false));
-    test("Given a bigint returns false", () => expect(isFunction(BigInt(10))).toBe(false));
-    test("Given a boolean returns false", () => expect(isFunction(true)).toBe(false));
-    test("Given undefined returns false", () => expect(isFunction(undefined)).toBe(false));
-    test("Given a symbol returns false", () => expect(isFunction(Symbol())).toBe(false));
-    test("Given null returns false", () => expect(isFunction(null)).toBe(false));
-    test("Given object returns false", () => expect(isFunction({})).toBe(false));
-    test("Given array returns false", () => expect(isFunction([])).toBe(false));
+    test("Given a non-function returns false", () => {
+        expect(isFunction("test")).toBe(false);
+        expect(isFunction(10)).toBe(false);
+        expect(isFunction(BigInt(10))).toBe(false);
+        expect(isFunction(true)).toBe(false);
+        expect(isFunction(undefined)).toBe(false);
+        expect(isFunction(Symbol())).toBe(false);
+        expect(isFunction(null)).toBe(false);
+        expect(isFunction({})).toBe(false);
+        expect(isFunction([])).toBe(false);
+    });
 });