diff --git a/src/libs/urlopen.test.ts b/src/libs/urlopen.test.ts
new file mode 100644
index 00000000..c12b19c4
--- /dev/null
+++ b/src/libs/urlopen.test.ts
@@ -0,0 +1,159 @@
+import { describe, it, expect, beforeEach, afterEach } from "vitest";
+import { validate, ErrorType } from "./urlopen";
+
+// Mock window.location if not in browser environment
+const mockLocation = {
+  protocol: "http:",
+  hostname: "localhost",
+};
+
+Object.defineProperty(global, "window", {
+  value: {
+    location: mockLocation,
+  },
+  writable: true,
+});
+
+describe("validate", () => {
+  let originalProtocol: string;
+
+  beforeEach(() => {
+    // Save original protocol
+    originalProtocol = window.location.protocol;
+  });
+
+  afterEach(() => {
+    // Restore original protocol
+    Object.defineProperty(window.location, "protocol", {
+      writable: true,
+      value: originalProtocol,
+    });
+  });
+
+  describe("when URL is empty", () => {
+    it("should return ErrorType.None", () => {
+      expect(validate("")).toBe(ErrorType.None);
+    });
+  });
+
+  describe("when URL is root relative", () => {
+    it("should return ErrorType.None", () => {
+      expect(validate("/static/style.json")).toBe(ErrorType.None);
+    });
+  });
+
+  describe("when window.location.protocol is https:", () => {
+    beforeEach(() => {
+      Object.defineProperty(window.location, "protocol", {
+        writable: true,
+        value: "https:",
+      });
+    });
+
+    it("should return EmptyHttpsProtocol when URL has no protocol", () => {
+      expect(validate("example.com")).toBe(ErrorType.EmptyHttpsProtocol);
+      expect(validate("www.example.com/path")).toBe(ErrorType.EmptyHttpsProtocol);
+    });
+
+    it("should return None for valid https URLs", () => {
+      expect(validate("https://example.com")).toBe(ErrorType.None);
+      expect(validate("https://www.example.com/path")).toBe(ErrorType.None);
+    });
+
+    it("should return CorsError for http URLs pointing to non-local hosts", () => {
+      expect(validate("http://example.com")).toBe(ErrorType.CorsError);
+      expect(validate("http://api.example.com/endpoint")).toBe(ErrorType.CorsError);
+    });
+
+    it("should return None for http URLs pointing to localhost", () => {
+      expect(validate("http://localhost")).toBe(ErrorType.None);
+      expect(validate("http://localhost:3000")).toBe(ErrorType.None);
+      expect(validate("http://127.0.0.1")).toBe(ErrorType.None);
+      expect(validate("http://127.0.0.1:8080")).toBe(ErrorType.None);
+      expect(validate("http://127.255.255.255")).toBe(ErrorType.None);
+    });
+
+    it("should return None for http URLs pointing to IPv6 localhost", () => {
+      expect(validate("http://[::1]")).toBe(ErrorType.None);
+      expect(validate("http://[::1]:3000")).toBe(ErrorType.None);
+    });
+
+    it("should return None for other protocols", () => {
+      expect(validate("ftp://example.com")).toBe(ErrorType.None);
+      expect(validate("ws://example.com")).toBe(ErrorType.None);
+      expect(validate("wss://example.com")).toBe(ErrorType.None);
+    });
+  });
+
+  describe("when window.location.protocol is http:", () => {
+    beforeEach(() => {
+      Object.defineProperty(window.location, "protocol", {
+        writable: true,
+        value: "http:",
+      });
+    });
+
+    it("should return EmptyHttpOrHttpsProtocol when URL has no protocol", () => {
+      expect(validate("example.com")).toBe(ErrorType.EmptyHttpOrHttpsProtocol);
+      expect(validate("www.example.com/path")).toBe(ErrorType.EmptyHttpOrHttpsProtocol);
+    });
+
+    it("should return None for valid http URLs", () => {
+      expect(validate("http://example.com")).toBe(ErrorType.None);
+      expect(validate("http://www.example.com/path")).toBe(ErrorType.None);
+    });
+
+    it("should return None for valid https URLs", () => {
+      expect(validate("https://example.com")).toBe(ErrorType.None);
+      expect(validate("https://www.example.com/path")).toBe(ErrorType.None);
+    });
+
+    it("should return None for localhost URLs", () => {
+      expect(validate("http://localhost")).toBe(ErrorType.None);
+      expect(validate("http://127.0.0.1")).toBe(ErrorType.None);
+    });
+  });
+
+  describe("edge cases", () => {
+    it("should handle URLs with ports", () => {
+      Object.defineProperty(window.location, "protocol", {
+        writable: true,
+        value: "https:",
+      });
+
+      expect(validate("https://example.com:8443")).toBe(ErrorType.None);
+      expect(validate("http://example.com:8080")).toBe(ErrorType.CorsError);
+      expect(validate("http://localhost:3000")).toBe(ErrorType.None);
+    });
+
+    it("should handle URLs with paths and query strings", () => {
+      Object.defineProperty(window.location, "protocol", {
+        writable: true,
+        value: "https:",
+      });
+
+      expect(validate("https://example.com/path?query=value")).toBe(ErrorType.None);
+      expect(validate("http://example.com/path?query=value")).toBe(ErrorType.CorsError);
+    });
+
+    it("should handle malformed URLs that cannot be parsed", () => {
+      Object.defineProperty(window.location, "protocol", {
+        writable: true,
+        value: "https:",
+      });
+
+      expect(validate("not a url at all")).toBe(ErrorType.EmptyHttpsProtocol);
+      expect(validate("://")).toBe(ErrorType.EmptyHttpsProtocol);
+    });
+
+    it("should handle localhost variations case-insensitively", () => {
+      Object.defineProperty(window.location, "protocol", {
+        writable: true,
+        value: "https:",
+      });
+
+      expect(validate("http://LOCALHOST")).toBe(ErrorType.None);
+      expect(validate("http://LocalHost:3000")).toBe(ErrorType.None);
+    });
+  });
+});
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