We use collections in our test code extensively. Sharing few tips which can be handy while selecting the data structure based on usage patterns:

- Fixed size or variable size
- Duplicate allowed or not
- Ordering is needed or not
- Traversal is forward directional or bi-directional
- Insertion at the end or any arbitrary position
- More inserts or more reads
- Concurrently accessed or not
- Modification is allowed or not
- Nature of data is homogeneous or heterogeneous