add doctest in unittest (#229)

Author: johnnychen94

Project.toml

@@ -10,7 +10,8 @@ Statistics = "10745b16-79ce-11e8-11f9-7d13ad32a3b2"
 julia = "1"
 
 [extras]
+Documenter = "e30172f5-a6a5-5a46-863b-614d45cd2de4"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 
 [targets]
-test = ["Test"]
+test = ["Documenter", "Test"]

src/FixedPointNumbers.jl

@@ -168,7 +168,7 @@ except in scenarios where they are guaranteed to have hardware support.
 
 A classic usage is to avoid overflow behavior by promoting `FixedPoint` to `AbstractFloat`
 
-```jldoctest
+```jldoctest; setup = :(using FixedPointNumbers)
 julia> x = N0f8(1.0)
 1.0N0f8
 

test/runtests.jl

@@ -6,6 +6,9 @@ else
     @test isempty(detect_ambiguities(FixedPointNumbers, Base, Core))
 end
 
+using Documenter
+doctest(FixedPointNumbers, manual = false)
+
 @testset "normed" begin
     include("normed.jl")
 end