add npm test

.gitignore

@@ -0,0 +1 @@
+node_modules/

Makefile

@@ -2,7 +2,7 @@ container := eslint-import-resolver-vite
 
 .PHONY: dev
 dev:
-	docker run -t -i -v `pwd`:/usr/app -w /usr/app --rm --name $(container) node:12-alpine
+	docker run -t -i -v `pwd`:/usr/app -w /usr/app --rm --name $(container) node:18-alpine
 
 .PHONY: shell
 shell:

index.test.js

@@ -0,0 +1,54 @@
+const resolve = require("resolve");
+const resolver = require("./index");
+
+jest.mock("resolve");
+jest.mock("fs");
+
+describe("Resolver Plugin Tests", () => {
+    beforeEach(() => {
+        jest.restoreAllMocks();
+    });
+
+    test("should resolve core module", () => {
+        resolve.isCore.mockReturnValue(true);
+
+        const result = resolver.resolve("fs", "/path/to/file.js", {});
+
+        expect(result.found).toBe(true);
+        expect(result.path).toBe(null);
+    });
+
+    test("should resolve non-core module", () => {
+        resolve.sync = jest.fn((source) => "/path/to/resolved.js");
+
+        jest.mock("/path/to/vite.config.js", () => ({
+            default: {
+                resolve: {
+                    extensions: [".js"],
+                    alias: {
+                        "_": "/path/to/src",
+                    },
+                },
+            }
+        }), { virtual: true });
+
+        const result = resolver.resolve("_/module", "/path/to/file.js", { configPath: "/path/to/vite.config.js" });
+
+        expect(result.found).toBe(true);
+        expect(result.path).toBe("/path/to/resolved.js");
+        expect(resolve.sync).toHaveBeenCalledWith("/path/to/src/module", {
+            basedir: "/path/to",
+            extensions: [".js"],
+        });
+    });
+
+    test("should handle resolve error", () => {
+        resolve.sync = jest.fn(() => {
+            throw new Error("Resolve error");
+        });
+
+        const result = resolver.resolve("module", "/path/to/file.js", {});
+
+        expect(result.found).toBe(false);
+    });
+});