1 files changed, 45 insertions, 0 deletions
diff --git a/spec/lib/gitlab/instrumentation/redis_interceptor_spec.rb b/spec/lib/gitlab/instrumentation/redis_interceptor_spec.rb
new file mode 100644
index 00000000000..25506d63091
--- /dev/null
+++ b/spec/lib/gitlab/instrumentation/redis_interceptor_spec.rb
@@ -0,0 +1,45 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+require 'rspec-parameterized'
+
+describe Gitlab::Instrumentation::RedisInterceptor, :clean_gitlab_redis_shared_state, :request_store do
+  using RSpec::Parameterized::TableSyntax
+
+  describe 'read and write' do
+    where(:setup, :command, :expect_write, :expect_read) do
+      # The response is 'OK', the request size is the combined size of array
+      # elements. Exercise counting of a status reply.
+      [] | [:set, 'foo', 'bar'] | 3 + 3 + 3 | 2
+
+      # The response is 1001, so 4 bytes. Exercise counting an integer reply.
+      [[:set, 'foobar', 1000]] | [:incr, 'foobar'] | 4 + 6 | 4
+
+      # Exercise counting empty multi bulk reply
+      [] | [:hgetall, 'foobar'] | 7 + 6 | 0
+
+      # Hgetall response length is combined length of keys and values in the
+      # hash. Exercises counting of a multi bulk reply
+      [[:hset, 'myhash', 'field', 'hello world']] | [:hgetall, 'myhash'] | 7 + 6 | 5 + 11
+
+      # Exercise counting of a bulk reply
+      [[:set, 'foo', 'bar' * 100]] | [:get, 'foo'] | 3 + 3 | 3 * 100
+
+      # Nested array response: ['123456-89', ['foo', 'bar']]
+      [[:xadd, 'mystream', '123456-89', 'foo', 'bar']] | [:xrange, 'mystream', '-', '+'] | 6 + 8 + 1 + 1 | 9 + 3 + 3
+    end
+
+    with_them do
+      it 'counts bytes read and written' do
+        Gitlab::Redis::SharedState.with do |redis|
+          setup.each { |cmd| redis.call(cmd) }
+          RequestStore.clear!
+          redis.call(command)
+        end
+
+        expect(Gitlab::Instrumentation::Redis.read_bytes).to eq(expect_read)
+        expect(Gitlab::Instrumentation::Redis.write_bytes).to eq(expect_write)
+      end
+    end
+  end
+end