Designing and manufacturing a custom Android tablet involves more than selecting components and installing Android. Achieving system reliability, performance consistency, and long-term maintainability requires thorough validation of how the Android operating system interfaces with the hardware. This is especially true when building custom devices with unique hardware requirements, advanced sensors, or niche-use applications.
Among the system integrity verification tools provided by Google, the Vendor Test Suite (VTS) plays a critical role in ensuring that a device’s low-level software aligns with Android’s standards. VTS is not as well-known as CTS (Compatibility Test Suite), but it addresses a foundational part of the Android system—the interface between the operating system and the underlying hardware.
This article provides a detailed overview of VTS: what it does, how it works, why it matters, when to use it, and how it benefits devices both with and without Google Mobile Services (GMS). It also includes other valuable tools that a custom Android manufacturer like Hatch uses to build stable, secure Android products.
What Is Google VTS?
The VTS is a set of automated tests developed by Google to validate the vendor implementation layer in Android. This layer includes:
- The Linux kernel
- Device drivers (e.g., for Wi-Fi, audio, USB)
- Hardware Abstraction Layers (HALs), which allow Android to communicate with hardware in a consistent and modular way
- SELinux policies and other low-level security configurations
These components live in the /vendor partition, which is separate from Android’s /system partition. This separation was formalized under Project Treble, which was introduced in Android 8.0 to make Android more modular and easier to update across different hardware platforms.
VTS ensures that the vendor partition is implemented in compliance with Android’s standards, promoting system stability and upgradeability.
Why VTS Matters in Custom Android Development
Devices built using the Android Open Source Project (AOSP) often include customized hardware. These may be tablets with industrial sensors, medical interfaces, rugged housing, or enterprise-specific software stacks. Custom HALs and drivers must be written to make these hardware components work properly with Android.
The challenge arises when these low-level components are not implemented correctly or diverge too far from Android’s standards. This can result in:
- Unpredictable behavior under stress or over time
- Incompatibility with future Android versions
- Security vulnerabilities due to misconfigured access policies
- Failure to pass certification tests if GMS is required
Running VTS helps identify and correct these issues during the development cycle. It verifies that HALs, kernel drivers, and SELinux configurations meet strict guidelines—reducing risk during deployment and post-launch updates.
Benefits of VTS for Devices with GMS
Devices that include Google Mobile Services (GMS) must pass a suite of compatibility and quality tests defined by Google. This includes CTS, GTS (Google Test Suite), and other security and performance benchmarks.
While VTS is not mandatory for GMS certification, it strongly supports the certification process in several ways:
- Prevents HAL or driver issues that could cause CTS failures
CTS tests rely on stable HAL implementations. If a device’s camera, Wi-Fi, or sensor HAL is unstable, CTS may fail. - Improves system robustness, reducing GTS and field failures
GMS includes background services, analytics, and auto-updating apps that can stress test a device in real-world usage. A solid vendor implementation reduces crash rates and system errors reported back to Google. - Ensures readiness for future Android versions
GMS-certified devices are often required to support at least one major Android update. VTS compliance helps ensure that vendor-specific code won’t block future upgrades.
In summary, VTS complements CTS and GTS by focusing on the foundation: if the base layers of the system are not stable, app compatibility and user experience cannot be guaranteed.
Benefits of VTS for Devices without GMS
For custom Android devices that do not include GMS, VTS is equally important.
Non-GMS devices often serve specialized roles: point-of-sale terminals, kiosks, rugged industrial tablets, educational devices, or region-specific products that do not rely on Google services. These products may not be subject to Google’s certification requirements, but they still need to:
- Maintain system stability under load
- Provide long-term software support
- Support regulatory and enterprise certifications
- Reduce development and maintenance costs
In short, for any custom Android manufacturer serving enterprise or industrial markets, VTS helps avoid costly support issues and accelerates product reliability.
How VTS Works: A High-Level Overview
VTS is executed from a host Linux machine connected to the device via ADB (Android Debug Bridge). It uses Trade Federation (TradeFed), a test harness that controls the test execution and collects results.
VTS includes a wide range of test categories:
| Test Type | What It Does |
| HAL Interface Tests | Ensures HALs follow AIDL or HIDL interface definitions |
| Kernel API Tests | Checks system calls, memory access, and driver behaviors |
| SEPolicy Tests | Verifies SELinux security policies are not overly permissive |
| Binder Fuzzing | Tries unexpected data inputs to test system robustness |
| Device Tree and Boot Config Tests | Confirms system configuration files are correct |
Each module produces pass/fail results, with detailed logs that guide developers in fixing issues.
How VTS Fits into the Product Development Lifecycle
A typical custom Android manufacturer integrates VTS into multiple stages:
| Stage | Use of VTS |
| Early Prototyping | Run targeted VTS modules to catch hardware-specific bugs |
| BSP Finalization | Run the full suite before vendor code is considered stable |
| Pre-Certification (GMS or internal QA) | Combine VTS with CTS, GTS, and CTS Verifier for full validation |
| Factory QA (Optional) | Spot-check units during production to ensure consistency |
This staged approach ensures alignment with Android standards throughout development.
VTS vs. Other Android Test Suites
Several other Android test suites complement VTS in different areas:
| Suite | Purpose | Best For |
| CTS | Tests Android APIs and app behavior | Required for GMS certification |
| CTS Verifier | Manual tests for sensors, displays, USB, etc. | Hardware integration QA |
| GTS | Tests Google apps and services | GMS validation |
| Monkey / MonkeyRunner | Simulates random UI inputs | Stability under stress |
| Burn-In Tests | Simulates real-world continuous usage | Factory and batch QA |
| Syzkaller / AFL | Kernel fuzzing tools | Advanced security validation |
Together with VTS, these tools form a complete QA strategy for any custom Android tablet project.
Common Causes of VTS Failures
The most common VTS failures stem from issues such as:
- Incorrect or incomplete HALs
- Misconfigured SELinux policies
- Non-compliant kernel drivers
- Improper system properties or boot parameters
Addressing these issues often requires coordination between the firmware team, kernel engineers, and platform developers—a process where an experienced partner like Hatch provides clear value.
Conclusion: Why Every Custom Android Manufacturer Should Use VTS
The Vendor Test Suite provides a foundation for building a high-quality, long-lasting Android device. Whether a product includes GMS or operates independently, VTS delivers benefits in the form of greater system stability, easier OS upgrades, and better long-term maintainability.
For any custom Android manufacturer, incorporating VTS into the development process leads to:
- More reliable hardware-software integration
- Fewer bugs during and after deployment
- Faster certification and time-to-market
- Lower post-sale support costs
Hatch is a global custom Android manufacturer offering full-stack engineering services for hardware, firmware, and certification support. From HAL development to VTS, CTS, and GMS compliance, Hatch ensures that every custom Android tablet meets the demands of modern enterprise, industrial, and commercial markets.
Contact Hatch to explore how Android testing and compliance services can improve product quality and reduce development risks.
