Platforms and users that interact with ERC20 tokens expect a certain behaviour from those smart contracts. Nowadays security audit is the only way to check the compliance with the standard. This option is expensive and slow. Moreover auditors often check source code rather than the deployed contract itself, so they don't consider current state of the smart contract.
TestSuite is a DApp that checks compliance of a deployed token with ERC20 standard. The test results along with their evidence are available on-chain and in the web-interface.
There are different options, how you can run tests.
Go to the testsuite.net, then follow the steps on the website. You will need metamask to interact with the DApp.
TestSuite smart contract is deployed at Mainnet, Ropsten and Kovan. Just call check(address token) function. You can get results via testResults(address token) function.
Check the solidity/README.md to correctly interpret returned number.
The project consists of two parts:
Each part has it's own documentation.