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merged 3 commits into from
Oct 27, 2020
Merged

Add color keyword argument #1

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761c4ff
Add `color` keyword argument
kimikage Oct 22, 2020
076f427
Change the default value of `color` kwarg to `false`
kimikage Oct 25, 2020
eff09b8
Update README.md
kimikage Oct 27, 2020
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13 changes: 13 additions & 0 deletions README.md
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Expand Up @@ -21,6 +21,8 @@ See the docstring for full documentation.

## Known limitations

### Separately stored `stdout` or `stderr` objects

The capturing does not work properly if `f` prints to the `stdout` object that has been
stored in a separate variable or object, e.g.:

Expand Down Expand Up @@ -56,6 +58,17 @@ Stacktrace:
This is because `stdout` and `stderr` within an `iocapture` actually refer to the temporary
redirect streams which get cleaned up at the end of the `iocapture` call.

### ANSI color/escape code

On Julia v1.6 and later, the captured output of `iocapture` inherits the `:color` property
of the `stdout` or `stderr` by default. The colorization can be disabled by setting the
`color` keyword argument of `iocapture` to `false`.

On the other hand, on Julia v1.5 or earlier, even if the `color` keyword argument is set to
`true`, no coloring will be applied. However, this limitation might be removed in the
future, so you should specify `color=false` if you want to avoid coloring.


## Similar packages

* [Suppressor.jl](https://github.com/JuliaIO/Suppressor.jl) provides similar functionality,
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21 changes: 16 additions & 5 deletions src/IOCapture.jl
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Expand Up @@ -4,7 +4,7 @@ using Logging
export iocapture

"""
iocapture(f; throwerrors=true)
iocapture(f; throwerrors=true, color=true)

Runs the function `f` and captures the `stdout` and `stderr` outputs without printing them
in the terminal. Returns an object with the following fields:
Expand All @@ -21,6 +21,10 @@ The behaviour can be customized with the following keyword arguments:
via the `.value` field (with also `.error` and `.backtrace` set accordingly). If set to
`:interrupt`, only `InterruptException`s are rethrown.

* `color`: if set to `true` (default), `iocapture` inherits the `:color` property of
`stdout` and `stderr`, which specifies whether ANSI color/escape codes are expected. This
argument is only effective on Julia v1.6 and later.

# Extended help

`iocapture` works by temporarily redirecting the standard output and error streams
Expand Down Expand Up @@ -49,7 +53,7 @@ It is also possible to set `throwerrors = :interrupt`, which will make `iocaptur
only `InterruptException`s. This is useful when you want to capture all the exceptions, but
allow the user to interrupt the running code with `Ctrl+C`.
"""
function iocapture(f; throwerrors::Union{Bool,Symbol}=true)
function iocapture(f; throwerrors::Union{Bool,Symbol}=true, color::Bool=true)
# Currently, :interrupt is the only valid Symbol value for throwerrors
if isa(throwerrors, Symbol) && throwerrors !== :interrupt
throw(DomainError(throwerrors, "Invalid value passed for throwerrors"))
Expand All @@ -62,10 +66,17 @@ function iocapture(f; throwerrors::Union{Bool,Symbol}=true)
# Redirect both the `stdout` and `stderr` streams to a single `Pipe` object.
pipe = Pipe()
Base.link_pipe!(pipe; reader_supports_async = true, writer_supports_async = true)
redirect_stdout(pipe.in)
redirect_stderr(pipe.in)
if VERSION >= v"1.6.0-DEV.481" # https://github.com/JuliaLang/julia/pull/36688
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@MichaelHatherly MichaelHatherly Oct 25, 2020

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Worth sticking a @static in here to avoid the runtime branch?

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@kimikage kimikage Oct 25, 2020

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I'm skeptical that there is a runtime branch, but I'll stick the @static to be clear.

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@MichaelHatherly MichaelHatherly Oct 25, 2020

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Yeah, looks like it's smart enough these days:

julia> function f(x, y)
           if VERSION >= v"1.4.0"
               x + y
           else
               x - y
           end
       end

julia> @code_typed f(1, 2)
CodeInfo(
1 ─ %1 = Base.add_int(x, y)::Int64
└──      return %1
) => Int64

No point adding @static then.

pe_stdout = IOContext(pipe.in, :color => get(stdout, :color, false) & color)
pe_stderr = IOContext(pipe.in, :color => get(stdout, :color, false) & color)
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@mortenpi mortenpi Oct 24, 2020

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Should this be get(stderr, ...)?

else
pe_stdout = pipe.in
pe_stderr = pipe.in
end
redirect_stdout(pe_stdout)
redirect_stderr(pe_stderr)
# Also redirect logging stream to the same pipe
logger = ConsoleLogger(pipe.in)
logger = ConsoleLogger(pe_stderr)

# Bytes written to the `pipe` are captured in `output` and converted to a `String`.
output = UInt8[]
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25 changes: 22 additions & 3 deletions test/runtests.jl
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Expand Up @@ -5,6 +5,10 @@ using Test
# Note: this can not be inside the testset
(VERSION < v"1.2.0-DEV.272") && (hasfield(::Type{T}, name::Symbol) where T = Base.fieldindex(T, name, false) > 0)

hascolor(io) = VERSION >= v"1.6.0-DEV.481" && get(io, :color, false)
has_escapecodes(s) = occursin(r"\e\[[^m]*m", s)
strip_escapecodes(s) = replace(s, r"\e\[[^m]*m" => "")

# Callable object for testing
struct Foo
x
Expand Down Expand Up @@ -61,13 +65,25 @@ end
@test c.value === nothing

# Colors get discarded
c = iocapture() do
c = iocapture(color=false) do
printstyled("foo", color=:red)
end
@test !c.error
@test c.output == "foo"
@test c.value === nothing

# Colors are preserved if it's supported
c = iocapture() do
printstyled("foo", color=:red)
end
@test !c.error
if hascolor(stdout)
@test c.output == "\e[31mfoo\e[39m"
else
@test c.output == "foo"
end
@test c.value === nothing

# This test checks that deprecation warnings are captured correctly
c = iocapture() do
println("println")
Expand All @@ -83,9 +99,12 @@ end
@test isdefined(Base, :JLOptions)
@test hasfield(Base.JLOptions, :depwarn)
if Base.JLOptions().depwarn == 0 # --depwarn=no, default on Julia >= 1.5
@test c.output == "println\n[ Info: @info\n"
@test has_escapecodes(c.output) === hascolor(stderr)
@test strip_escapecodes(c.output) == "println\n[ Info: @info\n"
else # --depwarn=yes
@test startswith(c.output, "println\n[ Info: @info\n┌ Warning: depwarn\n")
@test has_escapecodes(c.output) === hascolor(stderr)
output_nocol = strip_escapecodes(c.output)
@test startswith(output_nocol, "println\n[ Info: @info\n┌ Warning: depwarn\n")
end

# Exceptions -- normally rethrown
Expand Down