Do not print anything related to extensions when they don't none exist

When extensions are supported but there's no one enabled in the
database, we should not print anything related to them in schema.rb.

2 files changed, 16 insertions, 4 deletions

diff --git a/activerecord/lib/active_record/schema_dumper.rb b/activerecord/lib/active_record/schema_dumper.rb
index 62403a29c6..df090b972d 100644
--- a/activerecord/lib/active_record/schema_dumper.rb
+++ b/activerecord/lib/active_record/schema_dumper.rb
@@ -70,11 +70,13 @@ HEADER
       def extensions(stream)
         return unless @connection.supports_extensions?
         extensions = @connection.extensions
-        stream.puts "  # These are extensions that must be enabled in order to support this database"
-        extensions.each do |extension|
-          stream.puts "  enable_extension #{extension.inspect}"
+        if extensions.any?
+          stream.puts "  # These are extensions that must be enabled in order to support this database"
+          extensions.each do |extension|
+            stream.puts "  enable_extension #{extension.inspect}"
+          end
+          stream.puts
         end
-        stream.puts
       end
 
       def tables(stream)
diff --git a/activerecord/test/cases/schema_dumper_test.rb b/activerecord/test/cases/schema_dumper_test.rb
index c5092e15ea..bbe1a14d00 100644
--- a/activerecord/test/cases/schema_dumper_test.rb
+++ b/activerecord/test/cases/schema_dumper_test.rb
@@ -237,8 +237,18 @@ class SchemaDumperTest < ActiveRecord::TestCase
       unless connection.extension_enabled?('hstore')
         connection.enable_extension 'hstore'
       end
+
       output = standard_dump
+      assert_match "# These are extensions that must be enabled", output
       assert_match %r{enable_extension "hstore"}, output
+
+      connection.extensions.each do |ext|
+        connection.disable_extension ext
+      end
+
+      output = standard_dump
+      assert_no_match "# These are extensions that must be enabled", output
+      assert_no_match %r{enable_extension}, output
     end
 
     def test_schema_dump_includes_xml_shorthand_definition