As discussed in What to test at dev stage?, the EUT at dev testing are Structural component and Feature. And the quality levels under consideration are L1 through L4.

Hence the scope of dev testing are all the tests pertaining to L1 through L4 and these are:

TestObjective
Data validation testTo ensure that invalid input data are rejected gracefully. Issues like data type issue, data format issue, data boundary issue, data dependency issue etc will be targeted.
GUI validation testTo ensure that the interface (GUI) through which the inputs are accepted is clean. Issues like layout of the screen, placement and grouping of elements in the screen, font/color/size, spelling mistakes, enable/disable behavior of screen elements etc will be targeted.
API validation testTo ensure that the interface (Non-GUI) through which the inputs are accepted is clean. Issues like number of arguments, order of arguments, type of arguments, return type and accessibility of the API etc will be targeted.
Structure testTo ensure that the internal code structure is clean. Issues like concurrency handling, timeout issues, exception handling, resource usage policy, data usage conditions, linkage of components etc will be targeted.
Functionality testTo ensure that the functional behavior of the "structural component" is implemented as intended. Issues like not considering condition(s) that govern the behavior of the component, misuse of conditions, wrong order of combining the conditions, missing possible value of a condition to consider etc will be targeted.