Add tests

[lxvm]

Is your feature request related to a problem? Please describe.

Creating this issue to track the status of the interface tests in Integrals.jl for providing fully-featured Julia integration libraries. The first item should be possible in v4 of Integrals. For the remaining items, some but not all of the libraries will support the features requested. In the cases these can be implemented, they will likely improve the correctness of the program.

Describe the solution you’d like

To add integration tests and derivative tests for (in order of importance):

• [ ] Update the interface tests to use IntegralFunctions and BatchIntegralFunctions, like the derivative tests
• [ ] types of quadrature points are the floating-point promotion of the types of the limits of integration (c.f. #221)
• [ ] shapes of array-valued integrands and parameters are preserved (e.g 0-d arrays, vectors, matrices, etc...)
• [x] complete infinite limit tests for the whole interface (#231)
• [ ] Get as close as possible to 100% code-coverage (e.g. by testing keywords of algorithms)
• [ ] additional numeric precision (e.g. single precision)
• [ ] additional numeric types (e.g. complex)
• [ ] integrals with unitful integrands and limits of integration