Adjusting tests to deal with floating point madness

espinafre · nyalldawson · commit 6a85309587d9 · 2020-06-18T08:34:33.000+10:00
PostgreSQL 11 and 12 handle floating point values differently; the test originally passed on PostgreSQL 12, but not on 11 (Travis). Now, with floating point data truncated to only 6 digits, they run on both versions of the DBMS. See https://www.postgresql.org/docs/12/release-12.html
diff --git a/tests/src/python/test_provider_postgres.py b/tests/src/python/test_provider_postgres.py
@@ -781,14 +781,15 @@ def testPktComposite(self):
 
         fields = vl.fields()
 
-        f = next(vl.getFeatures(QgsFeatureRequest().setFilterExpression('pk3 = 3.1415927')))
+        # Only 6 decimals for PostgreSQL 11.
+        f = next(vl.getFeatures(QgsFeatureRequest().setFilterExpression('pk3 = 3.14159')))
         # first of all: we must be able to fetch a valid feature
         self.assertTrue(f.isValid())
         self.assertEqual(f['pk1'], 1)
         self.assertEqual(f['pk2'], 2)
 
-        # round() needed to make sure Python older than 3.8 do the right thing.
-        self.assertEqual(round(f['pk3'], 5), round(3.1415927, 5))
+        # Only 6 decimals for PostgreSQL 11.
+        self.assertEqual(f['pk3'], 3.14159)
         self.assertEqual(f['value'], 'test 2')
 
         # can we edit a field?
@@ -799,12 +800,12 @@ def testPktComposite(self):
         # Did we get it right? Let's create a new QgsVectorLayer and try to read back our changes:
         vl2 = QgsVectorLayer('{} sslmode=disable srid=4326 table="qgis_test"."tb_test_compound_pk" (geom) key=\'"pk1","pk2","pk3"\' '.format(self.dbconn), "test_compound2", "postgres")
         self.assertTrue(vl2.isValid())
-        f2 = next(vl.getFeatures(QgsFeatureRequest().setFilterExpression('pk3 = 3.1415927')))
+        f2 = next(vl.getFeatures(QgsFeatureRequest().setFilterExpression('pk3 = 3.14159')))
         self.assertTrue(f2.isValid())
 
         # just making sure we have the correct feature
-        # round() needed to make sure Python older than 3.8 do the right thing.
-        self.assertEqual(round(f2['pk3'], 5), round(3.1415927, 5))
+        # Only 6 decimals for PostgreSQL 11.
+        self.assertEqual(f2['pk3'], 3.14159)
 
         # Then, making sure we really did change our value.
         self.assertEqual(f2['value'], 'Edited Test 2')
@@ -824,9 +825,7 @@ def testPktComposite(self):
         f4 = next(vl2.getFeatures(QgsFeatureRequest().setFilterExpression('pk2 = -9223372036854775800')))
 
         self.assertTrue(f4.isValid())
-        # round() needed to make sure Python older than 3.8 do the right thing.
-        expected_attrs = [4, -9223372036854775800, round(7.29154, 5), 'other test']
-        gotten_attrs = [f4['pk1'], f4['pk2'], round(f4['pk3'], 5), f4['value']]
+        expected_attrs = [4, -9223372036854775800, 7.29154, 'other test']
         self.assertEqual(f4.attributes(), expected_attrs)
 
         # Finally, let's delete one of the features.
@@ -854,11 +853,13 @@ def testPktFloat(self):
         vl = QgsVectorLayer('{} sslmode=disable srid=4326 key="pk" table="qgis_test"."tb_test_float_pk" (geom)'.format(self.dbconn), "test_floatpk", "postgres")
         self.assertTrue(vl.isValid())
         fields = vl.fields()
-        f = next(vl.getFeatures(QgsFeatureRequest().setFilterExpression('pk = 3.141592741')))
+        # floating point madness: PostgreSQL 11 only outputs 6 decimal digits for real type by default
+        # Thus, QGIS only stores 6 decimal digits in its attributes. For this reason,
+        # we must insert only 3.14159 instead of the more accurate 3.141592741 in the test table.
+        f = next(vl.getFeatures(QgsFeatureRequest().setFilterExpression('pk = 3.14159')))
         self.assertTrue(f.isValid())
 
-        # round() needed to make sure Python older than 3.8 do the right thing.
-        self.assertEqual(round(f['pk'], 5), round(3.1415927, 5))
+        self.assertEqual(f['pk'], 3.14159)
         self.assertEqual(f['value'], 'first test')
 
         # editing
@@ -869,7 +870,7 @@ def testPktFloat(self):
         # checking out if we really wrote to the table
         vl2 = QgsVectorLayer('{} sslmode=disable srid=4326 key="pk" table="qgis_test"."tb_test_float_pk" (geom)'.format(self.dbconn), "test_floatpk2", "postgres")
         self.assertTrue(vl2.isValid())
-        f2 = next(vl2.getFeatures(QgsFeatureRequest().setFilterExpression('pk = 3.141592741')))
+        f2 = next(vl2.getFeatures(QgsFeatureRequest().setFilterExpression('pk = 3.14159')))
 
         self.assertEqual(f2['value'], 'first check')
 
@@ -888,14 +889,15 @@ def testPktFloat(self):
         self.assertEqual(f4['value'], 'newly inserted')
 
         # Checking deletion
-        f5 = next(vl2.getFeatures(QgsFeatureRequest().setFilterExpression('pk = 2.7182817')))
+        # same as above: no more than 6 digits of Euler's number in the testdata for PostgreSQL 11.
+        f5 = next(vl2.getFeatures(QgsFeatureRequest().setFilterExpression('pk = 2.71828')))
         self.assertTrue(f5.isValid())
         vl2.startEditing()
         vl2.deleteFeatures([f5.id()])
         self.assertTrue(vl2.commitChanges())
 
         # did we really delete?
-        f_iterator = vl.getFeatures(QgsFeatureRequest().setFilterExpression('pk = 2.7182817'))
+        f_iterator = vl.getFeatures(QgsFeatureRequest().setFilterExpression('pk = 2.71828'))
         got_feature = True
 
         try:
diff --git a/tests/testdata/provider/testdata_pg_bigint_pk.sql b/tests/testdata/provider/testdata_pg_bigint_pk.sql
@@ -116,7 +116,7 @@ CREATE TABLE qgis_test.tb_test_compound_pk
 
 INSERT INTO qgis_test.tb_test_compound_pk (pk1, pk2, pk3, value, geom) VALUES
     (1, 1, 1.0, 'test 1', ST_SetSRID(ST_Point(-47.930, -15.818), 4326)),
-    (1, 2, 3.141592741, 'test 2', ST_SetSRID(ST_Point(-47.887, -15.864), 4326)),
+    (1, 2, 3.14159, 'test 2', ST_SetSRID(ST_Point(-47.887, -15.864), 4326)),
     (2, 2, 2.718281828, 'test 3', ST_SetSRID(ST_Point(-47.902, -15.763), 4326)),
     (2, 2, 1.0, 'test 4', ST_SetSRID(ST_Point(-47.952, -15.781), 4326));
 
@@ -128,5 +128,5 @@ CREATE TABLE qgis_test.tb_test_float_pk
 );
 
 INSERT INTO qgis_test.tb_test_float_pk (pk, value, geom) VALUES
-    (3.141592741, 'first test', ST_SetSRID(ST_Point(-47.887, -15.864), 4326)),
-    (2.718281828, 'second test', ST_SetSRID(ST_Point(-47.902, -15.763), 4326));
+    (3.14159, 'first test', ST_SetSRID(ST_Point(-47.887, -15.864), 4326)),
+    (2.71828, 'second test', ST_SetSRID(ST_Point(-47.902, -15.763), 4326));
