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Kernel#capture replaced by version which can catch output from subpro…

…cesses
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1 parent c7e233c commit 346ccf376c13bef58e575474a2f717b78dfa583d @route route committed Sep 26, 2012
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1 activesupport/CHANGELOG.md
@@ -1,4 +1,5 @@
## Rails 4.0.0 (unreleased) ##
+* Kernel#capture can catch output from subprocesses *Dmitry Vorotilin*
* Make callstack attribute optional in
ActiveSupport::Deprecation::Reporting methods `warn` and `deprecation_warning`
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37 activesupport/lib/active_support/core_ext/kernel/reporting.rb
@@ -1,4 +1,5 @@
require 'rbconfig'
+require 'tempfile'
module Kernel
# Sets $VERBOSE to nil for the duration of the block and back to its original
@@ -66,19 +67,33 @@ def suppress(*exception_classes)
# Captures the given stream and returns it:
#
- # stream = capture(:stdout) { puts 'Cool' }
- # stream # => "Cool\n"
+ # stream = capture(:stdout) { puts 'notice' }
+ # stream # => "notice\n"
+ #
+ # stream = capture(:stderr) { warn 'error' }
+ # stream # => "error\n"
+ #
+ # even for subprocesses:
+ #
+ # stream = capture(:stdout) { system('echo notice') }
+ # stream # => "notice\n"
+ #
+ # stream = capture(:stderr) { system('echo error 1>&2') }
+ # stream # => "error\n"
def capture(stream)
- begin
- stream = stream.to_s
- eval "$#{stream} = StringIO.new"
- yield
- result = eval("$#{stream}").string
- ensure
- eval("$#{stream} = #{stream.upcase}")
- end
+ stream = stream.to_s
+ captured_stream = Tempfile.new(stream)
+ stream_io = eval("$#{stream}")
+ origin_stream = stream_io.dup
+ stream_io.reopen(captured_stream)
+
+ yield
- result
+ stream_io.rewind
+ return captured_stream.read
+ ensure
+ captured_stream.unlink
+ stream_io.reopen(origin_stream)
end
alias :silence :capture
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2 activesupport/test/core_ext/kernel_test.rb
@@ -51,6 +51,8 @@ class << o; @x = 1; end
def test_capture
assert_equal 'STDERR', capture(:stderr) { $stderr.print 'STDERR' }
assert_equal 'STDOUT', capture(:stdout) { print 'STDOUT' }
+ assert_equal "STDERR\n", capture(:stderr) { system('echo STDERR 1>&2') }
+ assert_equal "STDOUT\n", capture(:stdout) { system('echo STDOUT') }
end
end

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