1 files changed, 78 insertions, 0 deletions
diff --git a/railties/test/generators/db_system_change_generator_test.rb b/railties/test/generators/db_system_change_generator_test.rb
new file mode 100644
index 0000000000..d476bfd2dc
--- /dev/null
+++ b/railties/test/generators/db_system_change_generator_test.rb
@@ -0,0 +1,78 @@
+# frozen_string_literal: true
+
+require "generators/generators_test_helper"
+require "rails/generators/rails/db/system/change/change_generator"
+
+module Rails
+  module Generators
+    module Db
+      module System
+        class ChangeGeneratorTest < Rails::Generators::TestCase
+          include GeneratorsTestHelper
+
+          setup do
+            copy_gemfile(
+              GemfileEntry.new("sqlite3", nil, "Use sqlite3 as the database for Active Record")
+            )
+          end
+
+          test "change to invalid database" do
+            output = capture(:stderr) do
+              run_generator ["--to", "invalid-db"]
+            end
+
+            assert_match <<~MSG.squish, output
+              Invalid value for --to option.
+              Supported preconfigurations are:
+              mysql, postgresql, sqlite3, oracle, frontbase,
+              ibm_db, sqlserver, jdbcmysql, jdbcsqlite3,
+              jdbcpostgresql, jdbc.
+            MSG
+          end
+
+          test "change to postgresql" do
+            run_generator ["--to", "postgresql"]
+
+            assert_file("config/database.yml") do |content|
+              assert_match "adapter: postgresql", content
+              assert_match "database: test_app", content
+            end
+
+            assert_file("Gemfile") do |content|
+              assert_match "# Use pg as the database for Active Record", content
+              assert_match "gem 'pg'", content
+            end
+          end
+
+          test "change to mysql" do
+            run_generator ["--to", "mysql"]
+
+            assert_file("config/database.yml") do |content|
+              assert_match "adapter: mysql2", content
+              assert_match "database: test_app", content
+            end
+
+            assert_file("Gemfile") do |content|
+              assert_match "# Use mysql2 as the database for Active Record", content
+              assert_match "gem 'mysql2'", content
+            end
+          end
+
+          test "change to sqlite3" do
+            run_generator ["--to", "sqlite3"]
+
+            assert_file("config/database.yml") do |content|
+              assert_match "adapter: sqlite3", content
+              assert_match "db/development.sqlite3", content
+            end
+
+            assert_file("Gemfile") do |content|
+              assert_match "# Use sqlite3 as the database for Active Record", content
+              assert_match "gem 'sqlite3'", content
+            end
+          end
+        end
+      end
+    end
+  end
+end