Small eigen collider

Small Eigen Collider Creating random ruby programs Andrew Grimm

Rationale
Unit tests of existing projects failed on Rubinius because of bugs in things like String#split or StringIO#gets
If I could generate random programs, I could see whether less popular implementations did the same thing as more popular implementations

Producing random code result = @receiver.send(@method, @parameter_objects, &:inspect) Where @receiver and @parameter_objects are randomly chosen objects, and @method is a randomly chosen method name.

Logging the results
Currently printing the receiver, method, parameter objects and the result
Receiver object: “a” Method: “casecmp” Parameters: [“b”] Result: -1

Comparing the results
Run the script under different ruby versions
Do a diff on the outputs

Example of a diff
Lines above were running “a”.casecmp(“b”)
diff MRI_output.txt rubinius_output.txt 180c180 < Result: -1 --- > Result: 1

Contents of the two files MRI_output.txt Receiver object: "a" Method: "casecmp" Parameters: ["b"] Result: -1 rubinius_output.txt Receiver object: “a” Method: “casecmp” Parameters: [“b”] Result: 1

Manual confirmation rvm ruby -e 'puts [RUBY_ENGINE, “a”.casecmp”b”].join(“ ”) jruby -1 macruby -1 ruby -1 rbx 1 <= spot the odd one out

Protip
Test the !@#$ing happy path!
describe "String#casecmp" do it "is a case-insensitive version of String#<=>" do "abcdef".casecmp("abcde").should == 1 "aBcDeF".casecmp("abcdef").should == 0 "abcdef".casecmp("abcdefg").should == -1 "abcdef".casecmp("ABCDEF").should == 0 end # Snipped I18N tests end

Current tasks
Make as safe as ruby allows (grain of salt here)
Rather than randomly generating tasks each time, allow the tasks to be generated once, and run many times

Making the program safe Receiver object: nil Method: “system” Parameters: [“rm -rf /”] Result: :(
Applying $SAFE to try to prevent bad things in a ruby-specific way
Researching other sandboxing methods

Generate once, run many times
Currently, I give all the rubies the same random number generator seed and same set of objects, and leave it up to them to choose which objects are in each task
JRuby gives different random values than other platforms
If the choice of tasks were made only once, then I could compare JRuby with others

Questions?

Small eigen collider

by Andrew Grimm on Nov 08, 2010

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