Add "after" param to log

after query param allows to get only parts that come after a specified
number, for example "after: 10" will download only parts that come after
10th part.

lib/travis/api/v2/http/log.rb

@@ -39,6 +39,7 @@ module Travis
             def log_parts
               parts = log.parts
               parts = parts.where(number: part_numbers) if part_numbers
+              parts = parts.where(["number > ?", after]) if after
               parts.sort_by(&:number).map do |part|
                 {
                   'id' => part.id,
@@ -49,6 +50,11 @@ module Travis
               end
             end
 
+            def after
+              after = options['after'].to_i
+              after == 0 ? nil : after
+            end
+
             def part_numbers
               if numbers = options['part_numbers']
                 numbers.is_a?(String) ? numbers.split(',').map(&:to_i) : numbers

spec/integration/v2/jobs_spec.rb

@@ -51,6 +51,18 @@ describe 'Jobs' do
     end
 
     context 'with chunked log requested' do
+      it 'responds with only selected chunks if after is specified' do
+        job.log.parts << Log::Part.new(content: 'foo', number: 1, final: false)
+        job.log.parts << Log::Part.new(content: 'bar', number: 2, final: true)
+        job.log.parts << Log::Part.new(content: 'bar', number: 3, final: true)
+
+        headers = { 'HTTP_ACCEPT' => 'application/vnd.travis-ci.2+json; chunked=true' }
+        response = get "/jobs/#{job.id}/log", { after: 1 }, headers
+        body = JSON.parse(response.body)
+
+        body['log']['parts'].map { |p| p['number'] }.sort.should == [2, 3]
+      end
+
       it 'responds with only selected chunks if part_numbers are requested' do
         job.log.parts << Log::Part.new(content: 'foo', number: 1, final: false)
         job.log.parts << Log::Part.new(content: 'bar', number: 2, final: true)