Without writing the test cases is good approach to test the product or software in Agile process?
We have Several projects are lined up along with the product testing. Due to time urgency and time constraints the test cases are not writing up for some functions and UI and doing the testing without test cases. In this situation I felt and observed some bugs are raising in the client SIT environment testing. I know it is kind of bad approach in the testing.
Can anyone suggest me your feedback and ideas and this to avoid the leakage in the client environment.
You should consider time-boxed exploratory testing and risk-based testing - both approaches have their benefits and compliment each other if you're able to execute them both.
Exploratory testing is an approach to software testing that is concisely described as simultaneous learning, test design and test execution.
Risk-based testing functions as an organisational principle used to prioritise the tests of features and functions in software, based on the risk of failure, the function of their importance and likelihood or impact of failure.
The latter is especially useful when pushed for time, as you're able to test the highest risk areas and have confidence that no high priority / severity defects exist in the product before handing over to the client.