The Complete Guide to Testing Deep Links on Android & iOS

Do you depend daily on apps launching instantly from emails, texts or search results? Deep links power those seamless mobile experiences – when coded properly. We rely on deep links functioning flawlessly across devices.

But have you ever angrily clicked a link expecting one place, yet strangely landed somewhere unexpected? Or worse – the screen spins endlessly trying to load?

We‘ve all been there. I‘ll let you in on a secret though – virtually every broken mobile moment traces back to flimsy deep link testing.

This guide brings to light what exactly deep links and deeplink testing entail behind the scenes – empowering you to deliver rocksolid mobile apps users love.

First, let‘s quickly level-set the mobile landscape and importance of deep link testing specifically…

Why Deep Link Testing Demands Dedicated Attention

Over 85% of time on mobile devices occurs inside apps rather than browsers. Users expect effortlessly transitioning between apps and web pages. Deep links enable those seamless jumps into specific parts of apps.

Consider how often you click email links to launch directly to products, articles or other destinations without tedious navigation. Deeplinks streamline this through custom protocols pointing at internal app locations instead of external web pages.

yourApp://specificScreen?content=1234

Those links coupling websites to mobile applications require intricate functionality testing across endless permutations of:

• Operating systems
• Device models
• App versions
• Real-world use conditions

So what exactly can go wrong with deep links? Plenty:

• Links launch wrong app or wrong screen
• App crashes or hangs attempting to open
• Fail silently without notifications or error messages
• Don‘t work when app is already running or closed
• Stop functioning after OS updates

Each failure erodes user trust and satisfaction in your app. So let‘s get serious about deep link testing…

Deeplink Testing Core Concepts

Before diving hands-on into testing tactics for Android and iOS, we need solid foundations regarding how deeplinks actually work under the hood.

Deep links contain multiple components like traditional web URLs:

Custom scheme defines a protocol handled by the target app like yourapp://. The host identifies an endpoint like support.yourapp.com.

The path points toward internal screens like /products/5678 and query parameters pass data payloads such as campaign IDs.

Now we can classify common types of deep links:

Default – Opens app if installed, fails if not.
Deferred – If app missing, sends to app store or website.
Contextual – Default/Deferred with extra manually-set metadata.

Next let‘s shift gears into hardcore mobile test automation techniques…

How to Test Deep Links on Android

When tackling Android deep link testing, I leverage a combination of approaches to validate functionality across devices and use cases:

Low-level test commands…High-level test automation…Manual real device testing – Android requires multi-pronged verification.

Let me walk through pros and cons of each major testing toolset:

Using Android Debug Bridge (ADB)

The Android Debug Bridge from command line facilitates quick tests granting visibility into OS-level intent handling:

adb shell am start -W -a VIEW -d "yourDeepLink"

This rapidly validates an individual deep link without needing full automation stacks.

Pros: Simple, fast root access to Android intents
Cons: Only verifies one link at a time, limited error visibility

Testing with Appium Framework

Appium test automation shines for testing entire real-world user flows spanning multiple screens and conditional branches:

@Test 
public void testDeferredDeepLink() {

  driver.get("defer://promo/abcd?...");  

  // Assert app store launched if needed

  Assert.assertTrue(driver.currentActivity().contains("PromoScreen")); 

}

Java/Kotlin Appium tests offer power across devices, but require programming expertise.

Pros: Full user flow automation, CI/CD integration
Cons: Steeper learning curve, slower debug cycles

Employing Espresso and Intent Matching

Espresso natively integrates with Android Studio for streamlined UI test creation:

@Test
public void verifyDeepLinkIntent() {

  openDeepLink();

  Intended(hasAction(Intent.ACTION_VIEW)); 

} 

Special intent matching APIs validate intended app navigation happens internally.

Pros: Tight IDE integration and intent inspection
Cons: Still needs programming, Android-only

Now that we have Android covered, let‘s cross the mobile aisle towards iOS…

How to Test Deep Links on iOS

Over on the Apple side, I take advantage of Xcode‘s native XCUITest framework combined with launch techniques for complete iOS validation:

The main tradeoff comes down to manual real device testing vs. automated UI testing:

Utilizing XCUITest Test Launching

XCUITest allows programmatically installing, launching and removing app instances – perfect for testing deep link transitions:

app.activate() //Bring app to foreground

UIATarget.localTarget().launchApp() //Cold launch app

We can trigger the app state needed to simulate inbound deep links.

Pros: Native IDE integration, supports advanced user flows
Cons: Requires Swift programming skills

Launching Safari to Initiate Deep Link

Alternatively, manually interacting with Safari to open URLs exercises the end-to-end universal link configuration:

func testUniversalLink() {

  let safari = XCUIApplication()/Safari

  safari.launch()
  safari.typeText("https://myapp.com/dl")

  app.wait(for: .runningForeground)

  // Safari should redirect back to app  

} 

This validates the full real-world web-to-app environment leveraging actual Safari.

Pros: Simple, no programming
Cons: Manual steps don‘t scale across devices

Now that we have closed the loop on Android and iOS testing tactics, let‘s level up with some pro tips…

Pro Deep Link Testing Tips

While the previous sections provide a hands-on starting point, battle-hardened mobile teams apply additional due diligence for bulletproof deep link testing:

Here are my top recommendations:

Irregular App States – Background/terminated apps often mishandle links – test edge cases!
User Authentication – Logged in vs out users may reach different destinations from same link.
Network Conditions – Spotty connections could impede link functioning or timeout delays.

Date/Time Issues – Dynamic links containing date/time params may break in future.

Still Valid After App Updates? – Regress deep links with each release to prevent regressions!

Unusual Data Values – Injection odd strings and params during manual testing attempts to break things in style of pen testing.

Crowdsourced Exploratory Testing – Leverage a community to bash on links attempting the bizarre – astonishing defects revealed!

By combining together real devices, test automation, anomalous use cases and out-of-the-box manual testing, we can tackle mobile deep linking with full confidence.

Now let‘s call out some key resources to tap for amplifying testing efforts…

Top Tools for Mobile Deep Link Testing

Real Device Cloud Services – Platforms like BrowserStack enable scaled test automation across 3000+ unique real mobile devices hosted online. This grants flexibility impossible locally.

Appium – As illustrated earlier, Appium test suites drive mobile apps end-to-end, including deep link verification checkpoints across user flows. Cloud offerings integrate devices.

IDE Built-in Tools – Android Studio, Xcode and Espresso for native Android test creation or iOS with XCUITest accelerate test creation.

For additional assistance conducting mobile testing from automated builds to troubleshooting, checkout our dedicated resources or request expert support. Our team lives and breathes mobile app testing – we‘re happy to help!

Thanks for reading – now you have all the tools needed to tackle mobile deep linking with confidence. Here‘s to happier users and successful mobile initiatives! Now go unleash flawless mobile deep links out into the world.