A blockchain is a continuously growing list of records, called blocks, which are linked and secured using cryptography. Some examples include Bitcoin, Ripple, Ethereum. Each block typically contains a hash pointer as a link to a previous block, a timestamp and transaction data. The technology uses smart contract protocol or rule which is immutable, thus once deployed it stays permanent. Let’s say, an updated version of an existing contract is created to eliminate a production bug, manual transfer of the stored data is required--which is a cumbersome process.
It is due to these features that proper testing and validation has become more critical for blockchain applications in comparison to others.
Besides all requisite testing: functional, integration, security, performance and specialized testing; blockchain testing requires smart contract testing, node testing, and advanced level non-functional testing. Before we dive into the factors to be considered while testing, let’s talk about the challenges.
- Technology stack: A primary factor that influences testing is dependent on the underlying development platforms like Ethereum, Openchain or any customized platform. Industry-level guidelines and recommendations on the level of tests are available for both platforms, Openchain and Ethereum. But a detailed analysis and a test strategy are required to test the functionality that is custom-built.
- Performance testing: For performance testing, a replica of the production environment is required. However, to replicate the level of transaction and the delay in processing the transaction, it is difficult to execute performance testing. For example, to initiate a bitcoin transaction now, miners need to confirm and validate the transaction which may get delayed due to a surge in usage. This implementation cannot be replicated in a dummy environment.
- Integration testing: It is difficult to ensure that a blockchain implementation is flawless. Integrating a blockchain app with various systems and environment often poses great difficulty. So, the key responsibility is to ensure that the response from all interfaces is consistent and there are no disconnects. The challenge arises when there is lack of proper information on all interfaces along with their response status.
- Security: Node and shared ledger are the most important parts of the blockchain for securing a blockchain application. For instance, if a node on the network is attacked by something like DDoS, then the application hosted on blockchain will be affected.
In blockchain, transactions are replicated at high volume throughout the network, which is often a challenge as this may slow down the network. The following 4 key considerations must be factored in for a successful testing strategy for blockchain applications:
1. Smart contract testing: Validate the methods for smart contracts in the same way as we do in API testing, including validating the methods, verifying the boundary value, and verifying the conditional statement. Then, the validation of encryption for the smart contract should be sent to another system via a distributed ledger. The unit level testing for QAs is to test all the APIs for the smart contract individually and then perform integration testing.
2. Node testing: Blockchain functions in a peer-to-peer distributed network through network nodes using a specific protocol for authentication. It checks with the majority of nodes and approves the block for its validity to make a successful transaction. Hence all heterogeneous nodes must be independently tested.
3. Performance: To overcome the performance testing challenge we need to have all the details like network latency based on block size, network size, expected transaction size, and how long a query takes to return the output with specialized authentication protocol. Performance testing is carried out based on these parameters and to overcome the failover with an abrupt peak or a downside, we need to leverage cloud environment features like auto-scaling for chaotic situations.
4. Security: It is important to identify the integrity of the network. All transactions are cryptographically encrypted. However, once the identity layer is hacked instantaneous transaction cannot be stopped. Some testing needs to be considered for a secure transaction using blockchain technology by overcoming challenges such as:
- Access and authentication
- Secure hash, consensus algorithm
- Wallet signature method
- Private keys
- OWAPS guideline for mobile and web application
- Vulnerability assessment
- Validating information provided
While these factors affect the implementation of blockchain technology, the challenges are not limited to these as testing would depend on how blockchain has been implemented for your application. However, these factors will give a guideline to test effectively with proper validation and verification approach for the applications based on blockchain technology.