Don't crash if a source file doesn't exist

[chillpop]

In our CI setup, we're running into a crash in slather when trying to process a profdata file:

Errno::ENOENT: No such file or directory @ rb_check_realpath_internal - /{path on build machine}/DerivedData/Build/Intermediates.noindex/{redacted}.build/Debug-iphonesimulator/{redacted}.build/DerivedSources/resource_bundle_accessor.swift

{omitted for clarity}/gems/slather-2.6.1/lib/slather/project.rb:138:in realpath
{omitted for clarity}/gems/slather-2.6.1/lib/slather/project.rb:138:in block (2 levels) in pathnames_per_binary
{omitted for clarity}/gems/slather-2.6.1/lib/slather/project.rb:137:in map
{omitted for clarity}/gems/slather-2.6.1/lib/slather/project.rb:137:in block in pathnames_per_binary
{omitted for clarity}/gems/slather-2.6.1/lib/slather/project.rb:136:in each
{omitted for clarity}/gems/slather-2.6.1/lib/slather/project.rb:136:in reduce
{omitted for clarity}/gems/slather-2.6.1/lib/slather/project.rb:136:in pathnames_per_binary
{omitted for clarity}/gems/slather-2.6.1/lib/slather/project.rb:124:in block in profdata_coverage_files
{omitted for clarity}/gems/slather-2.6.1/lib/slather/project.rb:123:in each
{omitted for clarity}/gems/slather-2.6.1/lib/slather/project.rb:123:in profdata_coverage_files
{omitted for clarity}/gems/slather-2.6.1/lib/slather/project.rb:98:in coverage_files
{omitted for clarity}/gems/slather-2.6.1/lib/slather/coverage_service/cobertura_xml_output.rb:18:in post
{omitted for clarity}/gems/slather-2.6.1/lib/slather/command/coverage_command.rb:101:in post
{omitted for clarity}/gems/slather-2.6.1/lib/slather/command/coverage_command.rb:61:in execute
{omitted for clarity}/gems/clamp-1.3.2/lib/clamp/command.rb:66:in run
{omitted for clarity}/gems/clamp-1.3.2/lib/clamp/subcommand/execution.rb:18:in execute
{omitted for clarity}/gems/clamp-1.3.2/lib/clamp/command.rb:66:in run
{omitted for clarity}/gems/clamp-1.3.2/lib/clamp/command.rb:140:in run
{omitted for clarity}/gems/slather-2.6.1/bin/slather:17:in <top (required)>

The file that does not exist is autogenerated by Xcode for a Swift Package with a resource bundle. It cannot be found due to a complex CI setup where one machine compiles code for testing and a different machine runs the tests.

This failure happens when first parsing the coverage data and before we get a chance to ignore that file. I'd like to be able to get past the parsing step without crashing for missing files.

To resolve this, I'm checking to see if the filename from the coverage file exists on disk before calling realpath. If not, the path in the coverage file is used as is.

[coveralls]

Coverage increased (+0.005%) to 96.226% when pulling 9e73270 on chillpop:check-exists-for-realpath into 6fa3d4c on SlatherOrg:master.

[ksuther]

Thanks for the PR!

[chillpop]

Thanks for the merge @ksuther.
Do you know when you will be including this in a new Slather release?

[ksuther]

I'll try to do one in the next few days.