Fix and document an RSpec::Parameterized::TableSyntax edge-case

Signed-off-by: Rémy Coutable <remy@rymai.me>

1 files changed, 5 insertions, 5 deletions

diff --git a/doc/development/testing_guide/best_practices.md b/doc/development/testing_guide/best_practices.md
index 4cc3812b0f0..2c8d488877b 100644
--- a/doc/development/testing_guide/best_practices.md
+++ b/doc/development/testing_guide/best_practices.md
@@ -358,16 +358,11 @@ range of inputs, might look like this:
 describe "#==" do
   using RSpec::Parameterized::TableSyntax
 
-  let(:project1) { create(:project) }
-  let(:project2) { create(:project) }
   where(:a, :b, :result) do
     1         | 1        | true
     1         | 2        | false
     true      | true     | true
     true      | false    | false
-    project1  | project1 | true
-    project2  | project2 | true
-    project 1 | project2 | false
   end
 
   with_them do
@@ -380,6 +375,11 @@ describe "#==" do
 end
 ```
 
+CAUTION: **Caution:**
+Only use simple values as input in the `where` block. Using procs, stateful
+objects, FactoryBot-created objects etc. can lead to
+[unexpected results](https://github.com/tomykaira/rspec-parameterized/issues/8).
+
 ### Prometheus tests
 
 Prometheus metrics may be preserved from one test run to another. To ensure that metrics are