PortfolioOptimisers.jl: Instructions file for GitHub Copilot

Test Writing Guidelines for PortfolioOptimisers.jl

Test File Structure

• All test files must be named test-*.jl and placed in the test/ directory.
• Tests are auto-discovered and run by the test harness in test/runtests.jl.
• Each test file should focus on testing a specific module or feature.

Test Patterns

• Use @safetestset: All top-level test sets must use @safetestset to ensure isolation.

  @safetestset "Feature name tests" begin
      using Test, PortfolioOptimisers
      @testset "Specific functionality" begin
          # test code here
      end
  end
  

• Import required packages: Import all necessary packages inside the @safetestset block.

• Nested test sets: Use @testset for grouping related tests within a @safetestset.

Validation Testing

• Test argument validation: Always test that @argcheck validations work correctly.

  • Test for IsEmptyError, IsNothingError, DimensionMismatch, DomainError, etc.
  • Use @test_throws ErrorType function_call to verify error conditions.

• Example validation tests:

  @test_throws IsEmptyError Constructor(; v = [])
  @test_throws DimensionMismatch Constructor(; a = rand(3, 4), b = rand(2, 3))
  @test_throws DomainError Constructor(; x = Inf)
  

Test Coverage

• Tests should cover:

  • Normal use cases with valid inputs.
  • Edge cases (empty arrays, boundary values, etc.).
  • Error conditions (invalid inputs, dimension mismatches, etc.).
  • Type stability where relevant.

• Aim for comprehensive coverage of new functionality and edge cases.

Test Data

• Use simple, reproducible test data (e.g., rand(3, 4), 1:10, etc.).
• Use meaningful test data that exercises the feature being tested.
• For date/time tests, use Dates module: Date(2020, 1, 1) .+ Day.(0:2).

Test Organization

• Group related tests logically within @testset blocks.
• Use descriptive names for test sets and individual tests.
• Keep tests isolated - each test should be independent.