This repo explores how to use XUnit Theory tests with the InlineData attribute.

A given sequence of whole numbers all have the same delta (Δ), yet one number is missing. Find the missing number. For example:

Example 1: {1,2,4} Δ=1, Missing = 3
Example 2: {1,3,4} Δ=1, Missing = 2
Example 3: {2,6,8} Δ=2, Missing = 4
Example 4: {1,2,4,5} Δ=1, Missing = 3
Example 5: {10,20,40,50} Δ=10, Missing = 30
Example 6: {10,20,30,50} Δ=10, Missing = 40

Sequences of length 0, 1, or 2 are invalid. Malformed sequnces will not be passed in (all sequences are assumed to be legit)

This project makes use of XUnit Theory tests to allow multiple sequences to easily be tested. In each case, a sequence is passed as inline data, with the "missing" number being the last one. In the code below, the "real" sequence is:

{1, 2, 3, 4}

The theory tests allow different ways of expressing the missing number. For example:

[InlineData(1, 2, 4, 3)]

... represents the sequence {1,2,3,4}, but the "3" is missing. By placing the "3" at the end, the test Asserts the correct value was found.

Test cases end up looking like:

[Theory] // [item, item, item, MISSING NUMBER]
[InlineData(1, 2, 4, 3)]
[InlineData(1, 3, 4, 2)]
[InlineData(10, 12, 13, 11)]

This seems to provide a good balance between:

• Data driven tests
• The ability to put breakpoints on tests
• Human test readability
• Test maintainability

Other XUnit theory tests (ClassData, MemberData) were explored, but the "test noise" overwhelmed the clarity of the simpler solution.