test: add Vitest unit tests for location-detector and country-flags

src/lib/geo/tests/country-flags.test.ts

@@ -0,0 +1,17 @@
+import { describe, expect, test } from "vitest";
+import { getCountryCode } from "@/lib/geo/country-flags";
+
+describe("getCountryCode", () => {
+  test.each([
+    ["egypt", "eg"],
+    ["germany", "de"],
+    ["united_states", "us"],
+    ["uk", "gb"],
+  ])("returns the ISO code for %s", (slug, expected) => {
+    expect(getCountryCode(slug)).toBe(expected);
+  });
+
+  test.each(["atlantis", "", "EGYPT", "worldwide"])("returns null for %j", (slug) => {
+    expect(getCountryCode(slug)).toBeNull();
+  });
+});

src/lib/geo/tests/location-detector.test.ts

@@ -0,0 +1,76 @@
+import { describe, expect, test } from "vitest";
+import { detectCountry } from "@/lib/geo/location-detector";
+
+describe("detectCountry", () => {
+  describe("empty and invalid input", () => {
+    test("returns null for null", () => {
+      expect(detectCountry(null)).toBeNull();
+    });
+
+    test.each(["", " ", "   ", "\t\n"])("returns null for blank input %j", (input) => {
+      expect(detectCountry(input)).toBeNull();
+    });
+
+    test.each(["!!!", "###", "@#$%^&*()", "🌍", "(.*)", "[", "\\"])(
+      "returns null for special characters only: %s",
+      (input) => {
+        expect(detectCountry(input)).toBeNull();
+      },
+    );
+
+    test.each(["Mars", "Earth", "Remote"])(
+      "returns null when no country is present: %s",
+      (input) => {
+        expect(detectCountry(input)).toBeNull();
+      },
+    );
+  });
+
+  describe("exact match", () => {
+    test.each([
+      ["Egypt", "egypt"],
+      ["Germany", "germany"],
+      ["Tokyo, Japan", "japan"],
+      ["Jakarta, Indonesia", "indonesia"],
+      ["Cairo", "egypt"],
+      ["New Zealand", "new_zealand"],
+      ["South Korea", "south_korea"],
+      ["Hong Kong", "hong_kong"],
+    ])("detects %s as %s", (input, expected) => {
+      expect(detectCountry(input)).toBe(expected);
+    });
+
+    test("is case-insensitive", () => {
+      expect(detectCountry("EGYPT")).toBe("egypt");
+    });
+
+    test("ignores surrounding whitespace", () => {
+      expect(detectCountry("  Egypt  ")).toBe("egypt");
+    });
+
+    test("matches next to punctuation", () => {
+      expect(detectCountry("Cairo, Egypt!")).toBe("egypt");
+    });
+  });
+
+  describe("word boundaries", () => {
+    test.each([
+      ["Romania", "romania"],
+      ["Somalia", "somalia"],
+      ["Nigeria", "nigeria"],
+      ["Tirana", "albania"],
+      ["Indiana", "united_states"],
+    ])("%s is not matched by the country hidden inside it", (input, expected) => {
+      expect(detectCountry(input)).toBe(expected);
+    });
+
+    test.each([
+      ["Oman", "oman"],
+      ["Mali", "mali"],
+      ["Niger", "niger"],
+      ["Iran", "iran"],
+    ])("still matches the standalone word %s", (input, expected) => {
+      expect(detectCountry(input)).toBe(expected);
+    });
+  });
+});