Integration test suite: fix flaky TestInstanceSchemas

TestInstanceSchemas sometimes failed in MySQL 8.0.23 due to tables no longer
be returned from I_S in a consistent order. The test logic no longer makes
this assumption.

instance_test.go

@@ -2,7 +2,6 @@ package tengo
 
 import (
 	"database/sql"
-	"encoding/json"
 	"fmt"
 	"net/url"
 	"reflect"
@@ -387,6 +386,18 @@ func (s TengoIntegrationSuite) TestInstanceCanSkipBinlog(t *testing.T) {
 }
 
 func (s TengoIntegrationSuite) TestInstanceSchemas(t *testing.T) {
+	assertSame := func(s1, s2 *Schema) {
+		t.Helper()
+		if s1.Name != s2.Name {
+			t.Errorf("Schema names do not match: %q vs %q", s1.Name, s2.Name)
+		} else {
+			diff := s1.Diff(s2)
+			if diffCount := len(diff.ObjectDiffs()); diffCount > 0 {
+				t.Errorf("Schemas do not match: %d object diffs found", diffCount)
+			}
+		}
+	}
+
 	// Currently at least 4 schemas in testdata/integration.sql
 	schemas, err := s.d.Schemas()
 	if err != nil || len(schemas) < 4 {
@@ -406,18 +417,14 @@ func (s TengoIntegrationSuite) TestInstanceSchemas(t *testing.T) {
 			t.Errorf("Schema %s returned multiple times from call to instance.Schemas", schema.Name)
 		}
 		seen[schema.Name] = true
-		if !reflect.DeepEqual(schema, byName[schema.Name]) {
-			// Trying to get more insight into rare flaky failures in mysql 8
-			jsonBytes1, _ := json.Marshal(schema)
-			jsonBytes2, _ := json.Marshal(byName[schema.Name])
-			fmt.Printf("%s\n\n-------------\n\n%s\n", jsonBytes1, jsonBytes2)
-			t.Errorf("Mismatch for schema %s between Schemas and SchemasByName", schema.Name)
-		}
-		if schema2, err := s.d.Schema(schema.Name); err != nil || !reflect.DeepEqual(schema2, schema) {
-			t.Errorf("Mismatch for schema %s vs instance.Schema(%s); error=%s", schema.Name, schema.Name, err)
+		assertSame(schema, byName[schema.Name])
+		if schema2, err := s.d.Schema(schema.Name); err != nil {
+			t.Errorf("Unexpected error from Schema(%q): %v", schema.Name, err)
+		} else {
+			assertSame(schema, schema2)
 		}
 		if has, err := s.d.HasSchema(schema.Name); !has || err != nil {
-			t.Errorf("Expected HasSchema(%s)==true, instead found false", schema.Name)
+			t.Errorf("Expected HasSchema(%s)==true, instead found false / %v", schema.Name, err)
 		}
 	}