Add validation and skip logic at #truncate

app/models/ci/build_trace_chunk.rb

@@ -28,11 +28,14 @@ module Ci
     end
 
     def truncate(offset = 0)
-      self.append("", offset) if offset < size
+      raise ArgumentError, 'Offset is out of range' if offset > size || offset < 0
+      return if offset == size # Skip the following process as it doesn't affect anything
+
+      self.append("", offset)
     end
 
     def append(new_data, offset)
-      raise ArgumentError, 'Offset is out of range' if offset > data.bytesize || offset < 0
+      raise ArgumentError, 'Offset is out of range' if offset > size || offset < 0
       raise ArgumentError, 'Chunk size overflow' if CHUNK_SIZE < (offset + new_data.bytesize)
 
       set_data(data.byteslice(0, offset) + new_data)

spec/models/ci/build_trace_chunk_spec.rb

@@ -141,11 +141,7 @@ describe Ci::BuildTraceChunk, :clean_gitlab_redis_shared_state do
       context 'when offset is bigger than data size' do
         let(:offset) { data.bytesize + 1 }
 
-        it do
-          expect_any_instance_of(described_class).not_to receive(:append) { }
-
-          subject
-        end
+        it { expect { subject }.to raise_error('Offset is out of range') }
       end
 
       context 'when offset is 10' do