Unit and Functional Testing

Testing Base Julia

Julia is under rapid development and has an extensive test suite to verify functionality across multiple platforms. If you build Julia from source, you can run this test suite with make test. In a binary install, you can run the test suite using Base.runtests().

runtests([tests=["all"][, numcores=iceil(CPU_CORES/2)]])

Run the Julia unit tests listed in tests, which can be either a string or an array of strings, using numcores processors. (not exported)

Test Framework

The Test module contains macros and functions related to testing. A default handler is provided to run the tests, and a custom one can be provided by the user by using the registerhandler() function.

To use the default handler, the macro @test() can be used directly:

julia> using Base.Test

julia> @test 1 == 1

julia> @test 1 == 0
ERROR: test failed: 1 == 0
 in error at error.jl:21
 in default_handler at test.jl:19
 in do_test at test.jl:39

julia> @test error("This is what happens when a test fails")
ERROR: test error during error("This is what happens when a test fails")
This is what happens when a test fails
 in error at error.jl:21
 in anonymous at test.jl:62
 in do_test at test.jl:37

As seen in the examples above, failures or errors will print the abstract syntax tree of the expression in question.

Another macro is provided to check if the given expression throws an exception of type extype, @test_throws():

julia> @test_throws ErrorException error("An error")
ErrorException("An error")

julia> @test_throws BoundsError error("An error")
ERROR: test failed: error("An error")
 in error at error.jl:21
 in default_handler at test.jl:19
 in do_test_throws at test.jl:55

julia> @test_throws DomainError throw(DomainError())
DomainError()

julia> @test_throws DomainError throw(EOFError())
ERROR: test failed: throw(EOFError())
 in error at error.jl:21
 in default_handler at test.jl:19
 in do_test_throws at test.jl:55

As floating-point values can be imprecise, you can perform approximate equality checks using either @test a b (where , typed via tab completion of \approx, is the isapprox function) or use the macros @test_approx_eq macro (which differs from isapprox in that it treats NaN values as equal and has a smaller default tolerance) or @test_approx_eq_eps (which takes an extra argument indicating the relative tolerance):

julia> @test 1  0.999999999

julia> @test 1  0.999999
ERROR: test failed: 1 isapprox 0.999999
 in expression: 1  0.999999
 in error at error.jl:21
 in default_handler at test.jl:30
 in do_test at test.jl:53

julia> @test_approx_eq 1. 0.999999999
ERROR: assertion failed: |1.0 - 0.999999999| < 2.220446049250313e-12
  1.0 = 1.0
  0.999999999 = 0.999999999
 in test_approx_eq at test.jl:75
 in test_approx_eq at test.jl:80

julia> @test_approx_eq 1. 0.9999999999999

julia> @test_approx_eq_eps 1. 0.999 1e-2

julia> @test_approx_eq_eps 1. 0.999 1e-3
ERROR: assertion failed: |1.0 - 0.999| <= 0.001
  1.0 = 1.0
  0.999 = 0.999
  difference = 0.0010000000000000009 > 0.001
 in error at error.jl:22
 in test_approx_eq at test.jl:68

Handlers

A handler is a function defined for three kinds of arguments: Success, Failure, Error:

# An example definition of a test handler
test_handler(r::Success) = nothing
test_handler(r::Failure) = error("test failed: $(r.expr)")
test_handler(r::Error)   = rethrow(r)

A different handler can be used for a block (with with_handler()):

julia> using Base.Test

julia> custom_handler(r::Test.Success) = println("Success on $(r.expr)")
custom_handler (generic function with 1 method)

julia> custom_handler(r::Test.Failure) = error("Error on custom handler: $(r.expr)")
custom_handler (generic function with 2 methods)

julia> custom_handler(r::Test.Error) = rethrow(r)
custom_handler (generic function with 3 methods)

julia> Test.with_handler(custom_handler) do
         @test 1 == 1
         @test 1 != 1
       end
Success on :((1==1))
ERROR: Error on custom handler: :((1!=1))
 in error at error.jl:21
 in custom_handler at none:1
 in do_test at test.jl:39
 in anonymous at no file:3
 in task_local_storage at task.jl:28
 in with_handler at test.jl:24

The Success and Failure types include an additonal field, resultexpr, which is a partially evaluated expression. For example, in a comparison it will contain an expression with the left and right sides evaluated.

Macros

@test(ex)

Test the expression ex and calls the current handler to handle the result.

@test_throws(extype, ex)

Test that the expression ex throws an exception of type extype and calls the current handler to handle the result.

@test_approx_eq(a, b)

Test two floating point numbers a and b for equality taking in account small numerical errors.

@test_approx_eq_eps(a, b, tol)

Test two floating point numbers a and b for equality taking in account a margin of tolerance given by tol.

@inferred f(x)

Tests that the call expression f(x) returns a value of the same type inferred by the compiler. It’s useful to check for type stability.

f(x) can be any call expression. Returns the result of f(x) if the types match, and an Error Result if it finds different types.

julia> using Base.Test

julia> f(a,b,c) = b > 1 ? 1 : 1.0
f (generic function with 1 method)

julia> typeof(f(1,2,3))
Int64

julia> @code_warntype f(1,2,3)
Variables:
  a::Int64
  b::Int64
  c::Int64

Body:
  begin  # none, line 1:
      unless (Base.slt_int)(1,b::Int64)::Bool goto 0
      return 1
      0:
      return 1.0
  end::UNION{FLOAT64,INT64}

julia> @inferred f(1,2,3)
ERROR: return type Int64 does not match inferred return type Union{Float64,Int64}
 in error at ./error.jl:21

julia> @inferred max(1,2)
2

Functions

with_handler(f, handler)

Run the function f using the handler as the handler.