Testing smart contracts – top facts you need to know

You just can’t deploy smart contracts after building it, be it in Solidity or any other language. The blockchain contracts need to be tested and verified before they start running live. Smart contracts are now increasingly used to store and execute crucial financial assets, particularly in the DeFi zone. Any flaw or bug in these blockchain contracts could mean disaster for the companies working with smart contracts. Testing and verification help to get a thorough evaluation on source code of the contracts and allow timely detection of possible flaws, before it is too late. Also, being a blockchain application, smart contracts are completely immutable. You cannot edit or change any data embedded in these blockchain contracts once they go live. Check out more at

Two types of tests are followed while testing smart contracts- Automated as well as Manual testing. The post below offers a brief on both types of testing for the smart contracts.

Automated testing

Automated testing refers to execution of testing through automated tools. There are automated software tools that are specially designed to test blockchain contracts. One of the major benefits of automated testing is that it is always faster compared to manual testing. Besides, the automated process uses lesser resources, is faster, as well as assures higher coverage.

Read more: “smart contract” systems

There are two types of automated testing processes when it comes to automated testing of blockchain contracts.

  • Functional testing

This testing method is devised to check functionality of smart contracts. The test is needed to receive the validation that whether or not every function in smart contract source code performs as per expectations.

Functional testing is performed through 3 methods-

Unit testing- In this case, every single component comprising the blockchain contracts is checked and verified. It’s a fast and simple process, and offers clarity on the glitches existing in the contract.

Integration testing- The second tier of functional testing, integration testing refers to a process where all components are verified together. This process helps to locate errors popping up during interaction in between the various components of the blockchain contracts. This method is especially beneficial if you are working with a highly complex contract, featuring a long list of functions.

System testing- The last lap of functional verification, system testing works to check whether the product as a whole is being able to perform as per set technical requirements. This testing method evaluates blockchain contracts as a complete integrated product.

  • Static and dynamic testing

Static as well as dynamic testing looks into the security concerns of the blockchain contracts to find out bugs, if any.

Static testing- This testing method verifies bytecode or source code of blockchain contracts prior to sending them for execution. Put simply, this test enables developers to debug affected contract code even without operating the program. The static analyzers mostly look into lack of compliance and common vulnerabilities in blockchain smart contracts.

Dynamic testing- In this case, the blockchain contracts are verified in the runtime environment. The testing method works to check and evaluate contract behaviors at the time of execution. Based on that, the code analyzers prepare reports on violations and  vulnerabilities, if any.

Manual testing

Although automated testing saves time and assures better efficiency given lack of errors yet blockchain contracts testing is incomplete without manual testing.

Sometimes, you need human intelligence for locating glitches in the blockchain contracts code which automated testing might not be able to locate. In fact, the manual process could be helpful to find out those vulnerabilities which are present beyond the code- yet holds the power to affect the blockchain contracts. For example, a flawed communication with some off-chain component.

  • Code audit

Code auditing refers to in-depth evaluation of the source code of blockchain contracts in order to find probable security flaws, failure-points, as well as weak development practices. Now, code audits could be automated but since the discussion is about manual testing, this particular point refers to manual code audit in this case.

The goal behind this testing method is to find out probable attack points in the blockchain contracts. You can hire cybersecurity experts here to perform professional auditing to detect bugs or vulnerabilities that might endanger the safety and functionality of blockchain contracts.

  • Bug bounty

It refers to getting the testing done by a 3rd party programmer aka ethical hacker. In return, the programmer will be rewarded with financial reward, provided s/he is successful. The task of the programmer here would be to detect all the bugs and glitches present in the code of the blockchain contracts. This bounty program is a great opportunity for the emerging developer community to exercise their skills in the real world.

Besides, the bug bounty program can come handy if you are in a rush to launch the smart contracts on the mainnet and immediately need some extra hands to carry on the testing part.

The need for formal verification

For those new to the smart contracts world, it must be stressed here that the verification  or evaluation of blockchain contracts doesn’t end with the testing procedure- including both the testing procedures. There is an additional process that is performed right after the testing procedure- formal verification.

Why do you need formal verification?

The testing procedures mentioned above are helpful to check whether or not the blockchain contracts are able to offer the set expected results in regard to certain data inputs. But, these methods won’t be able to provide information about inputs that had not been mentioned during the testing procedure. In official terms, the testing methods alone won’t be able to assure “functional correctness”. It means the testing procedures are not enough to verify whether or not the blockchain contracts are capable of behaving as expected in regard to every condition and input value.

This is the place where blockchain developers need to invest in formal verification. This verification process utilizes formal techniques that include complex mathematical techniques to specify as well as verify the blockchain contracts. In other words, the formal verification process completes the evaluation of blockchain contracts before they are sent live.

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