Remove N+1 query for author in issues APIsh-add-uncached-query-limiter

This was being masked by the statement cache because only one author was used
per issue in the test..

Also adds support for an Rspec matcher `exceed_all_query_limit`.

1 files changed, 13 insertions, 0 deletions

diff --git a/doc/development/query_recorder.md b/doc/development/query_recorder.md
index 26d3355e94d..61e5e1afede 100644
--- a/doc/development/query_recorder.md
+++ b/doc/development/query_recorder.md
@@ -22,6 +22,19 @@ As an example you might create 5 issues in between counts, which would cause the
 
 > **Note:** In some cases the query count might change slightly between runs for unrelated reasons. In this case you might need to test `exceed_query_limit(control_count + acceptable_change)`, but this should be avoided if possible.
 
+## Cached queries
+
+By default, QueryRecorder will ignore cached queries in the count. However, it may be better to count
+all queries to avoid introducing an N+1 query that may be masked by the statement cache. To do this,
+pass the `skip_cached` variable to `QueryRecorder` and use the `exceed_all_query_limit` matcher:
+
+it "avoids N+1 database queries" do
+  control_count = ActiveRecord::QueryRecorder.new(skip_cached: false) { visit_some_page }.count
+  create_list(:issue, 5)
+  expect { visit_some_page }.not_to exceed_all_query_limit(control_count)
+end
+```
+
 ## Finding the source of the query
 
 It may be useful to identify the source of the queries by looking at the call backtrace.