test: add unit tests for getArchitecture and getAvx2 Windows ARM64 fallback logic (#153)

* Initial plan

* Add unit tests for getArchitecture function

Co-authored-by: xhyrom <56601352+xhyrom@users.noreply.github.com>

* Remove unused import in utils.spec.ts

Co-authored-by: xhyrom <56601352+xhyrom@users.noreply.github.com>

* Apply suggestion from @Copilot

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Merge pr-131 and resolve test file conflicts

Co-authored-by: xhyrom <56601352+xhyrom@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: xhyrom <56601352+xhyrom@users.noreply.github.com>
Co-authored-by: Jozef Steinhübl <generalkubo@gmail.com>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

tests/utils.spec.ts

@@ -1,5 +1,80 @@
-import { describe, expect, it } from "bun:test";
-import { getAvx2 } from "../src/utils";
+import { afterEach, describe, expect, it, spyOn } from "bun:test";
+import { getArchitecture, getAvx2 } from "../src/utils";
+import * as core from "@actions/core";
+
+describe("getArchitecture", () => {
+  let warningSpy: ReturnType<typeof spyOn>;
+
+  afterEach(() => {
+    warningSpy?.mockRestore();
+  });
+
+  it("should return x64 for Windows with arm64 architecture", () => {
+    warningSpy = spyOn(core, "warning");
+    const result = getArchitecture("windows", "arm64");
+
+    expect(result).toBe("x64");
+    expect(warningSpy).toHaveBeenCalledTimes(1);
+    expect(warningSpy).toHaveBeenCalledWith(
+      expect.stringContaining(
+        "⚠️ Bun does not provide native arm64 builds for Windows."
+      )
+    );
+  });
+
+  it("should return x64 for Windows with aarch64 architecture", () => {
+    warningSpy = spyOn(core, "warning");
+    const result = getArchitecture("windows", "aarch64");
+
+    expect(result).toBe("x64");
+    expect(warningSpy).toHaveBeenCalledTimes(1);
+    expect(warningSpy).toHaveBeenCalledWith(
+      expect.stringContaining(
+        "⚠️ Bun does not provide native arm64 builds for Windows."
+      )
+    );
+  });
+
+  it("should return aarch64 for non-Windows platforms with arm64", () => {
+    warningSpy = spyOn(core, "warning");
+    const result = getArchitecture("linux", "arm64");
+
+    expect(result).toBe("aarch64");
+    expect(warningSpy).not.toHaveBeenCalled();
+  });
+
+  it("should return aarch64 for macOS with arm64", () => {
+    warningSpy = spyOn(core, "warning");
+    const result = getArchitecture("darwin", "arm64");
+
+    expect(result).toBe("aarch64");
+    expect(warningSpy).not.toHaveBeenCalled();
+  });
+
+  it("should return original arch value for x64", () => {
+    warningSpy = spyOn(core, "warning");
+    const result = getArchitecture("windows", "x64");
+
+    expect(result).toBe("x64");
+    expect(warningSpy).not.toHaveBeenCalled();
+  });
+
+  it("should return original arch value for x86", () => {
+    warningSpy = spyOn(core, "warning");
+    const result = getArchitecture("linux", "x86");
+
+    expect(result).toBe("x86");
+    expect(warningSpy).not.toHaveBeenCalled();
+  });
+
+  it("should return original arch value for aarch64 on Linux", () => {
+    warningSpy = spyOn(core, "warning");
+    const result = getArchitecture("linux", "aarch64");
+
+    expect(result).toBe("aarch64");
+    expect(warningSpy).not.toHaveBeenCalled();
+  });
+});
 
 describe("getAvx2", () => {
   it("should return false when called with os: 'windows' and arch: 'arm64'", () => {