Add CheckError (#21)

src/ArgCheck.jl

@@ -1,7 +1,7 @@
 __precompile__()
 module ArgCheck
 using Base.Meta
-export @argcheck, @check
+export @argcheck, @check, CheckError
 
 include("checks.jl")
 end

src/checks.jl

@@ -1,3 +1,6 @@
+struct CheckError <: Exception
+    msg::String
+end
 abstract type AbstractCheckFlavor end
 struct ArgCheckFlavor <: AbstractCheckFlavor end
 struct CheckFlavor    <: AbstractCheckFlavor end
@@ -164,7 +167,7 @@ function expr_error_block(info, condition, preamble...)
 end
 
 default_exception_type(::ArgCheckFlavor) = ArgumentError
-default_exception_type(::CheckFlavor) = ErrorException
+default_exception_type(::CheckFlavor) = CheckError
 
 function build_error(info)
     build_error(info, info.checkflavor, info.options...)
@@ -187,14 +190,27 @@ error_message(info::FallbackErrorInfo) = "$(info.code) must hold."
 error_message(info::CallErrorInfo) = fancy_error_message(info)
 error_message(info::ComparisonErrorInfo) = fancy_error_message(info)
 
+function pretty_string(data)
+    io = IOBuffer()
+    ioc = IOContext(io; limit=true, compact=true)
+    show(ioc, data)
+    seekstart(io)
+    String(take!(io))
+end
+pretty_string(x::Number) = string(x)
+pretty_string(s::Symbol) = string(s)
+pretty_string(ex::Expr) = string(ex)
+
 function fancy_error_message(info)
     code = info.code
     exprs = info.argument_expressions
     values = info.argument_values
     lines = String[]
     foreach(exprs, values) do ex, val
-        if string(ex) != string(val)
-            push!(lines, "$ex => $val")
+        pex = pretty_string(ex)
+        pval = pretty_string(val)
+        if pex != pval
+            push!(lines, "$pex => $pval")
         end
     end
     firstline = if isempty(lines)

test/checks.jl

@@ -1,3 +1,4 @@
+using ArgCheck: pretty_string
 macro catch_exception_object(code)
     quote
         err = try
@@ -77,12 +78,12 @@ truthy(args...;kw...) = true
     @test err === MyExoticError(1,2)
 end
 
-@testset "error message comparison" begin
+@testset "error messages" begin
     x = 1.23455475675
     y = 2.345345345
     # comparison
     err = @catch_exception_object @argcheck x == y MyError
-    @test isa(err, MyError)
+    @test err isa MyError
     msg = err.msg
     @test contains(msg, string(x))
     @test contains(msg, string(y))
@@ -110,6 +111,17 @@ end
     @test contains(msg, string(x))
     @test contains(msg, string(y))
     @test contains(msg, "≦")
+
+    s = randstring()
+    arr = rand(1000:9999, 1000)
+    x = randn()
+    err = @catch_exception_object @check falsy(x, arr, s)
+    @test typeof(err) == CheckError
+    msg = err.msg
+    @test length(msg) < 2000
+    @test contains(msg, pretty_string(x))
+    @test contains(msg, pretty_string(arr))
+    @test contains(msg, pretty_string(s))
 end
 
 # In 
@@ -172,8 +184,22 @@ end
 
 @testset "@check" begin
     @check true
-    E = ErrorException
+    E = CheckError
     @test_throws E @check false
     @test_throws E @check false "oh no"
     @test_throws DimensionMismatch @check false DimensionMismatch
 end
+
+@testset "pretty_string" begin
+    @test pretty_string("asd") == "\"asd\""
+
+    data = rand(10000:99999, 1000)
+    str = pretty_string(data)
+    @test length(str) < 1000
+    @test contains(str, string(last(data)))
+    @test contains(str, string(first(data)))
+    @test !contains(str, "\n")
+
+    data = randn()
+    @test parse(Float64,pretty_string(data)) === data
+end