diff --git a/src/appdistribution/distribution.spec.ts b/src/appdistribution/distribution.spec.ts
new file mode 100644
index 00000000000..a8f73f63b16
--- /dev/null
+++ b/src/appdistribution/distribution.spec.ts
@@ -0,0 +1,134 @@
+import { expect } from "chai";
+import * as sinon from "sinon";
+import * as fs from "fs-extra";
+import { upload, Distribution, awaitTestResults, DistributionFileType } from "./distribution";
+import { AppDistributionClient } from "./client";
+import { UploadReleaseResult, ReleaseTest } from "./types";
+import * as utils from "../utils";
+
+describe("appdistribution/distribution", () => {
+  let mockClient: sinon.SinonStubbedInstance<AppDistributionClient>;
+  let statStub: sinon.SinonStub;
+  let logSuccessStub: sinon.SinonStub;
+
+  beforeEach(() => {
+    mockClient = sinon.createStubInstance(AppDistributionClient);
+    statStub = sinon.stub(fs, "statSync");
+    logSuccessStub = sinon.stub(utils, "logSuccess");
+  });
+
+  afterEach(() => {
+    sinon.restore();
+  });
+
+  describe("Distribution class", () => {
+    it("should construct valid IPA distribution", () => {
+      statStub.returns({ isFile: () => true });
+      const dist = new Distribution("app.ipa");
+      expect(dist.distributionFileType()).to.equal(DistributionFileType.IPA);
+      expect(dist.getFileName()).to.equal("app.ipa");
+    });
+
+    it("should construct valid APK distribution", () => {
+      statStub.returns({ isFile: () => true });
+      const dist = new Distribution("app.apk");
+      expect(dist.distributionFileType()).to.equal(DistributionFileType.APK);
+    });
+
+    it("should construct valid AAB distribution", () => {
+      statStub.returns({ isFile: () => true });
+      const dist = new Distribution("app.aab");
+      expect(dist.distributionFileType()).to.equal(DistributionFileType.AAB);
+    });
+
+    it("should throw if extension is invalid", () => {
+      expect(() => new Distribution("app.zip")).to.throw(/Unsupported file format/);
+    });
+
+    it("should throw if file does not exist", () => {
+      statStub.throws(new Error("ENOENT"));
+      expect(() => new Distribution("app.apk")).to.throw(/File app.apk does not exist/);
+    });
+
+    it("should throw if path is not a file", () => {
+      statStub.returns({ isFile: () => false });
+      expect(() => new Distribution("app.apk")).to.throw(/is not a file/);
+    });
+  });
+
+  describe("upload", () => {
+    let distribution: Distribution;
+
+    beforeEach(() => {
+      statStub.returns({ isFile: () => true });
+      distribution = new Distribution("app.apk");
+    });
+
+    it("should successfully upload and poll release", async () => {
+      mockClient.uploadRelease.resolves("operations/123");
+      mockClient.pollUploadStatus.resolves({
+        result: UploadReleaseResult.RELEASE_CREATED,
+        release: { displayVersion: "1.0", buildVersion: "1", name: "test-rel" } as unknown as any,
+      });
+
+      const res = await upload(
+        mockClient as unknown as AppDistributionClient,
+        "apps/123",
+        distribution,
+      );
+
+      expect(res.displayVersion).to.equal("1.0");
+      expect(logSuccessStub).to.have.been.calledWithMatch(/uploaded new release/);
+    });
+
+    it("should handle 404 upload error safely", async () => {
+      const error404 = new Error("Not found") as unknown as { status: number };
+      error404.status = 404;
+      mockClient.uploadRelease.rejects(error404);
+
+      await expect(
+        upload(mockClient as unknown as AppDistributionClient, "apps/123", distribution),
+      ).to.be.rejectedWith(/App Distribution could not find your app/);
+    });
+  });
+
+  describe("awaitTestResults", () => {
+    it("should succeed when all tests pass on first poll", async () => {
+      const releaseTests: ReleaseTest[] = [{ name: "tests/1", deviceExecutions: [] } as any];
+      mockClient.getReleaseTest.resolves({
+        name: "tests/1",
+        deviceExecutions: [{ state: "PASSED", device: { model: "Pixel" } as unknown as any }],
+      } as unknown as ReleaseTest);
+
+      const setTimeoutStub = sinon.stub(global, "setTimeout").callsFake((fn) => fn() as any);
+
+      await awaitTestResults(releaseTests, mockClient as any);
+
+      expect(logSuccessStub).to.have.been.calledWithMatch(/Automated test\(s\) passed/);
+      setTimeoutStub.restore();
+    });
+
+    it("should fail immediately when a test execution fails", async () => {
+      const releaseTests: ReleaseTest[] = [{ name: "tests/1", deviceExecutions: [] } as any];
+      mockClient.getReleaseTest.resolves({
+        name: "tests/1",
+        deviceExecutions: [
+          { state: "FAILED", failedReason: "Crash", device: { model: "Pixel" } as any },
+        ],
+      } as any);
+
+      const setTimeoutStub = sinon.stub(global, "setTimeout").callsFake((fn) => fn() as any);
+
+      let caughtError: any;
+      try {
+        await awaitTestResults(releaseTests, mockClient as any);
+      } catch (err) {
+        caughtError = err;
+      }
+
+      expect(caughtError).to.exist;
+      expect(caughtError.message).to.match(/Automated test failed/);
+      setTimeoutStub.restore();
+    });
+  });
+});