From 8d3f43f7a9dc0b83dd9ac82ac0270bfee88ed51f Mon Sep 17 00:00:00 2001
From: Hannes Ljungberg <hannes@5monkeys.se>
Date: Fri, 8 Nov 2019 21:20:13 +0100
Subject: [PATCH] [3.0.x] Fixed #30967 -- Fixed TrigramTest failures on
 PostgreSQL 12+.

Backport of 6e2f05b2e33a6c80c7a411ce76af7b5a08acb835 from master
---
 tests/postgres_tests/test_trigram.py | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/tests/postgres_tests/test_trigram.py b/tests/postgres_tests/test_trigram.py
index b340b41869d..2a123faa5e5 100644
--- a/tests/postgres_tests/test_trigram.py
+++ b/tests/postgres_tests/test_trigram.py
@@ -26,22 +26,26 @@ class TrigramTest(PostgreSQLTestCase):
 
     def test_trigram_similarity(self):
         search = 'Bat sat on cat.'
+        # Round result of similarity because PostgreSQL 12+ uses greater
+        # precision.
         self.assertQuerysetEqual(
             self.Model.objects.filter(
                 field__trigram_similar=search,
             ).annotate(similarity=TrigramSimilarity('field', search)).order_by('-similarity'),
             [('Cat sat on mat.', 0.625), ('Dog sat on rug.', 0.333333)],
-            transform=lambda instance: (instance.field, instance.similarity),
+            transform=lambda instance: (instance.field, round(instance.similarity, 6)),
             ordered=True,
         )
 
     def test_trigram_similarity_alternate(self):
+        # Round result of distance because PostgreSQL 12+ uses greater
+        # precision.
         self.assertQuerysetEqual(
             self.Model.objects.annotate(
                 distance=TrigramDistance('field', 'Bat sat on cat.'),
             ).filter(distance__lte=0.7).order_by('distance'),
             [('Cat sat on mat.', 0.375), ('Dog sat on rug.', 0.666667)],
-            transform=lambda instance: (instance.field, instance.distance),
+            transform=lambda instance: (instance.field, round(instance.distance, 6)),
             ordered=True,
         )