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Blockchain Testing Guide. Challenges in Blockchain Testing
Ievgen Ievdokymov
Senior QA Engineer
Blockchain was invented in the pursuit to provide immensely secure and efficient data management and storage. This technology is mostly associated with cryptocurrencies, but in reality, it has turned out that it can be useful across the most diverse domains. Finance, banking, healthcare, real estate, automotive, government, manufacturing, media, and insurance are just a few to mention. Consequently, the number of blockchain-based apps is rapidly growing. Along with this, the testing community has faced the necessity to test this kind of software. How can it be performed properly? What is worth particular attention?
What is Blockchain?
First of all, let’s dive deeper into what blockchain technology is and what its key properties are.
While blockchain technology was invented in 2008, these days it is still a hot subject. So what technology does lie behind it? Blockchain is Greek to most people. So let’s figure out together how it works.
Blockchain is usually defined as a distributed and decentralized database or digital ledger. What makes it different from a common database is its structure. In a blockchain, digital data is collected and stored in bulks that are called blocks and have a particular storage capacity. When new data is validated, this block is closed and linked to a previously added block by means of cryptography. In such a way a chain of multiple blocks is built.
Every block in a chain includes record or transaction data, a timestamp, own hash, a hash of a preceding block, and a nonce. A timestamp is the exact time of block creation. A hash serves as a digital footprint. In fact, this is digital information itself turned by a mathematical function into an alphanumeric string. As for nonce or ‘number used only once’, this is a 32 bits encrypted number that a miner must solve for new block verification and close. It is worth noting that this is a math problem of immense complexity to find a nonce generating an accepted hash.
A miner who first finds the right nonce reaps a reward encouraging them to keep on validating transactions.
Once a block is linked to a chain, its content cannot be deleted or modified. This is due to the fact that each block includes a hash of a proceeded block. In case a block is modified in any way, a hash gets changed too. Consequently, data tampering is detected immediately.
Theoretically, rollback is possible, but this would be incredibly difficult because for this the vast majority of the nodes (participants) should reach a corresponding consensus.
To sum it up, blockchain is immutable and transparent due to decentralization and cryptographic hashing.
Blockchain Types
Blockchain is going to be commonly used in the nearest future. Even today, there are a number of various blockchain platforms. Ethereum, IBM Blockchain, Tron, Stellar, and Corda are just a few to mention. Still, we’d like to draw your attention to the fact that there are three main categories of blockchain - it can be private, public, and hybrid.
A private blockchain suggests compulsory approval of each node before its joining. As long as in blockchains of this type all nodes are supposed to be reliable, their security layers are not so solid.
A public blockchain, on the contrary, lets anyone become a member of a network. Blockchains of this type must have solid cryptography and a consensus system to ensure rocket-solid security.
A hybrid blockchain is a combo of the above-described blockchain types. For example, enterprises can establish a private blockchain platform along with a public one. In this case, they restrict access to particular information in the blockchain while keeping the rest of it open.
The Main Properties of Blockchain
Blockchain has proved itself as being incredibly reliable and important. This technology is gaining popularity due to a range of its unique features. So, we cannot help but present the key characteristics of blockchain that are worth your attention:
Decentralization
The blockchain has become groundbreaking due to its decentralization. This means that there is no central authority. Neither an individual, a team of individuals, nor a corporation has control over the system. Instead, all network nodes together maintain and manage it. Every node has the same ledger copy, the same opportunities, and the same rights. Decentralization provides security and transparency.
Immutability
Immutability is one more noteworthy blockchain property. Once added record cannot be changed or deleted from the ledger. If a record contains a mistake, a new correct one must be added, but both of them will be saved and visible to all nodes within the network. Data immutability also contributes to security and complete traceability.
Unanimity
Any record or transaction is added to the chain only when the network majority confirms its validity and gives consent. Every blockchain provides a consensus that is a certain decision-making algorithm helping nodes quickly reach an unbiased agreement on the present state of a record/transaction. There are diverse consensus mechanisms, and each one comes with its own advantages and drawbacks.
Anonymity
Along with transparency, blockchain provides anonymity. This means that the identity of network members is anonymous.
Security
While the above-mentioned features significantly contribute to blockchain security, there is also an additional security layer which is solid encryption. All data is hashed cryptographically, and its blocks are also linked cryptographically.
Importance of Blockchain Testing
The advent of smart contracts has given an opportunity for the simulation of varied business processes. Consequently, now a great number of blockchain-based applications are created.
As with any other apps, blockchain-based apps also require comprehensive testing to ensure their smooth and secure work. By testing your blockchain app, not only do you please its users but also prevent catastrophe.
As mentioned before, immutability is one of the main blockchain properties, so any mistake cannot be eliminated. For instance, if there is a bug in a smart contract, deployment of a new correct smart contract is the only means to fix the consequences of the bug. Security flaws resulting in a hacker attack may require a global network change.
Therefore, in this case, testing is indeed a must.
Tests Сompulsory for Blockchain-Based Applications
Numerous tests must be executed in order to assure the superb quality of a blockchain-based app:
If an already available blockchain platform has been used, usually there is no need to test its components (nodes, block size, chain size, etc.) similarly to databases or messaging libs. However, it is still compulsory to carefully check smart contracts.
A smart contract is a program code inbuilt directly into the blockchain. It is executed automatically whenever the predetermined terms and conditions are fulfilled.
Once deployed smart contract stays on a blockchain forever, and it is paramount to be sure that it does not contain bugs. Consequently, smart contracts are carefully checked to make sure that business logic combinations along with corresponding triggers result in the proper execution of particular transactions.
Smart contract testing suggests a scrupulous investigation of its source code along with the execution of unit, integration, and system testing.
As a rule, smart contracts are checked through automated testing, but manual testing can be applied as well. Of course, the latter is rather time-incentive and requires specific skills because all lines of the code must be checked and evaluated but in its course, serious vulnerabilities can be identified that autotests may have not detected.
Challenges of Blockchain App Testing
There are some challenges related to blockchain app testing. So the main of them are presented below.
Specific knowledge and varied background
To execute decent testing of blockchain-based apps, QA specialists should have deep knowledge of blockchain, distributed systems, coding, cryptography, finance, etc. Moreover, these days there are several dozens of blockchain platforms on the market. Each of them has a certain tech stack. For smart contract implementation, some leverage widely used programming languages, while others use unique ones. For example, Solidity is used for Ethereum, and Plutus is used for Cardano. Therefore, testing each new blockchain-based app may require some new knowledge.
Lack of official standards
One of the main problems is a lack of official standards that would guide both the development and testing of apps based on blockchain.
Poor choice of tools
Nowadays, on the market, there are not enough automation tools enabling the deployment and configuration of blockchain in a “testing mode” within the boundaries of one machine.
Time-incentive test environment setup
It is needed to download a node, synchronize it with the rest, and test through a command line or API. Besides, if an app also leverages a certain wallet, it also should be downloaded and adjusted. The whole process usually takes a good deal of time.
Blockchain immutability
Because of blockchain immutability, rigorous smart contract testing is definitely a must. Test data requires exceptional care as well. As long as test data is also visible in a blockchain and stays there forever, it is essential to make sure that no sensitive data is used in tests.
Performance
The performance of an app is mainly determined by the performance of the used blockchain platform itself. Some blockchain platforms may limit latency and rate of transactions, and it is necessary to take it into account while designing a testing strategy. Still, it is indeed challenging to foresee the real-world loads on a blockchain as plenty of factors affect it.
Blockchain Testing Tools
Here are three commonly used automation testing solutions for blockchain-based apps:
Truffle
The framework is a perfect solution for automating smart contract testing in Ethereum-based apps. With its help, it is rather easy to write uncomplicated and manageable tests. Both JS and Solidity can be used for this. The framework smoothly works with popular test runners including Chai and Mocha.
Ethereum Tester
This open-source tool suite as its name suggests is a perfect match for testing applications based on Ethereum. Its main advantages are effortless setup as well as manageable API support for diverse requirements of testing.
Embark
This is one more popular testing framework that is mostly used when it comes to decentralized apps. It is assimilated with Ethereum, IPFS, and some decentralized communication platforms.
Takeaway
Blockchain is a rather sophisticated technology. However, apps based on blockchain provide numerous benefits. Security, traceability, transparency, and the ability to get rid of intermediacy are the most noteworthy ones.
Although blockchain-based apps have come with certain difficulties for the testing community, their testing is still compulsory. As blockchain adoption is constantly gaining momentum, QA specialists need to get new knowledge and master new skills.