Make SchemaLoader database-agnostic

SchemaLoader now introspects an ActiveRecord connection instead
of hardcoding SQLite in-memory. The SQLite setup moves to specs.

Author: bradgessler

lib/fixture_bot/rails/cli.rb

@@ -10,19 +10,12 @@ def self.exit_on_failure?
       end
 
       desc "generate FIXTURES_FILE [OUTPUT_DIR]", "Generate YAML fixtures from a DSL file"
-      option :schema, type: :string, default: "db/schema.rb", aliases: "-s", desc: "Path to schema.rb"
       def generate(fixtures_path, output_dir = "test/fixtures")
-        schema_path = options[:schema]
-
-        unless File.exist?(schema_path)
-          raise Thor::Error, "Schema file not found: #{schema_path}"
-        end
-
         unless File.exist?(fixtures_path)
           raise Thor::Error, "Fixtures file not found: #{fixtures_path}"
         end
 
-        schema = SchemaLoader.load_file(schema_path)
+        schema = SchemaLoader.load
         fixture_set = FixtureBot.define_from_file(schema, fixtures_path)
         YamlDumper.new(fixture_set).dump(output_dir)
 

lib/fixture_bot/rails/schema_loader.rb

@@ -6,36 +6,34 @@ module FixtureBot
   module Rails
     class SchemaLoader
 
-      def self.load_file(path)
-        new.load_file(path)
+      def self.load(connection = ActiveRecord::Base.connection)
+        new(connection).load
       end
 
-      def load_file(path)
-        ActiveRecord::Base.establish_connection(adapter: "sqlite3", database: ":memory:")
-        load(path)
+      def initialize(connection)
+        @connection = connection
+      end
 
-        conn = ActiveRecord::Base.connection
-        build_schema(conn)
-      ensure
-        ActiveRecord::Base.connection_pool.disconnect!
+      def load
+        build_schema
       end
 
       private
 
       INTERNAL_TABLES = %w[ar_internal_metadata schema_migrations].freeze
 
-      def build_schema(conn)
+      def build_schema
         schema = Schema.new
-        table_names = conn.tables - INTERNAL_TABLES
+        table_names = @connection.tables - INTERNAL_TABLES
 
-        join_table_names = detect_join_tables(conn, table_names)
+        join_table_names = detect_join_tables(table_names)
 
         (table_names - join_table_names).each do |name|
-          columns = conn.columns(name)
+          columns = @connection.columns(name)
             .reject { |c| skip_column?(c.name) }
             .map { |c| c.name.to_sym }
 
-          foreign_keys = conn.foreign_keys(name)
+          foreign_keys = @connection.foreign_keys(name)
           associations = foreign_keys.map do |fk|
             assoc_name = fk.column.sub(/_id$/, "")
             Schema::BelongsTo.new(
@@ -54,7 +52,7 @@ def build_schema(conn)
         end
 
         join_table_names.each do |name|
-          fk_columns = conn.columns(name)
+          fk_columns = @connection.columns(name)
             .select { |c| c.name.end_with?("_id") }
             .map { |c| c.name }
 
@@ -74,12 +72,12 @@ def skip_column?(name)
         %w[id created_at updated_at].include?(name)
       end
 
-      def detect_join_tables(conn, table_names)
+      def detect_join_tables(table_names)
         table_names.select do |name|
-          pk = conn.primary_key(name)
+          pk = @connection.primary_key(name)
           next false if pk
 
-          id_cols = conn.columns(name).select { |c| c.name.end_with?("_id") }
+          id_cols = @connection.columns(name).select { |c| c.name.end_with?("_id") }
           id_cols.size == 2
         end
       end

spec/fixture_bot/schema_loader_spec.rb

@@ -1,52 +1,44 @@
 # frozen_string_literal: true
 
 require "fixture_bot/rails"
-require "tmpdir"
 
 RSpec.describe FixtureBot::Rails::SchemaLoader do
-  let(:schema_content) do
-    <<~RUBY
-      ActiveRecord::Schema.define(version: 2024_01_01_000000) do
-        create_table "users", force: :cascade do |t|
-          t.string "name"
-          t.string "email"
-          t.timestamps
-        end
+  before do
+    ActiveRecord::Base.establish_connection(adapter: "sqlite3", database: ":memory:")
 
-        create_table "posts", force: :cascade do |t|
-          t.string "title"
-          t.text "body"
-          t.integer "author_id"
-          t.timestamps
-        end
+    ActiveRecord::Schema.define(version: 2024_01_01_000000) do
+      create_table "users", force: :cascade do |t|
+        t.string "name"
+        t.string "email"
+        t.timestamps
+      end
 
-        add_foreign_key "posts", "users", column: "author_id"
+      create_table "posts", force: :cascade do |t|
+        t.string "title"
+        t.text "body"
+        t.integer "author_id"
+        t.timestamps
+      end
 
-        create_table "tags", force: :cascade do |t|
-          t.string "name"
-          t.timestamps
-        end
+      add_foreign_key "posts", "users", column: "author_id"
 
-        create_table "posts_tags", id: false, force: :cascade do |t|
-          t.integer "post_id", null: false
-          t.integer "tag_id", null: false
-        end
+      create_table "tags", force: :cascade do |t|
+        t.string "name"
+        t.timestamps
       end
-    RUBY
-  end
 
-  let(:schema_path) do
-    dir = Dir.mktmpdir
-    path = File.join(dir, "schema.rb")
-    File.write(path, schema_content)
-    path
+      create_table "posts_tags", id: false, force: :cascade do |t|
+        t.integer "post_id", null: false
+        t.integer "tag_id", null: false
+      end
+    end
   end
 
   after do
-    FileUtils.rm_rf(File.dirname(schema_path))
+    ActiveRecord::Base.connection_pool.disconnect!
   end
 
-  subject(:schema) { described_class.load_file(schema_path) }
+  subject(:schema) { described_class.load }
 
   it "loads regular tables with columns" do
     expect(schema.tables.keys).to contain_exactly(:users, :posts, :tags)