Raise when seed finds no files.

lib/oaken.rb

@@ -16,9 +16,22 @@ module Stored
   singleton_class.attr_reader :lookup_paths
   @lookup_paths = ["db/seeds"]
 
+  def self.glob(path)
+    patterns = lookup_paths.map { File.join(_1, "#{path}{,/**/*}.rb") }
+
+    Pathname.glob(patterns).tap do |found|
+      raise NoSeedsFoundError, "found no seed files for #{path.inspect}" if found.none?
+    end
+  end
+  NoSeedsFoundError = Class.new ArgumentError
+
   class Loader
-    def initialize(path)
-      @entries = Pathname.glob("#{path}{,/**/*}.rb").sort
+    def self.from(paths)
+      new paths.flat_map { Oaken.glob _1 }
+    end
+
+    def initialize(entries)
+      @entries = entries
     end
 
     def load_onto(seeds) = @entries.each do |path|

lib/oaken/seeds.rb

@@ -62,17 +62,8 @@ class << self
     #   class PaginationTest < ActionDispatch::IntegrationTest
     #     setup { seed "cases/pagination" }
     #   end
-    def seed(*directories)
-      Oaken.lookup_paths.product(directories).each do |path, directory|
-        load_from Pathname(path).join(directory.to_s)
-      end
-    end
-
-    private def load_from(path)
-      @loader = Oaken::Loader.new path
-      @loader.load_onto self
-    ensure
-      @loader = nil
+    def seed(*paths)
+      Oaken::Loader.from(paths.map(&:to_s)).load_onto self
     end
 
     # `section` is purely for decorative purposes to carve up `Oaken.prepare` and seed files.

test/dummy/test/models/oaken_test.rb

@@ -96,4 +96,14 @@ def self.column_names = []
     assert mod.respond_to?(:users) # Now respond_to_missing? hits.
     refute mod.respond_to?(:hmhm)
   end
+
+  test "raises when no files found to seed" do
+    assert_raise(Oaken::NoSeedsFoundError) { seed "test/cases/missing" }.tap do |error|
+      assert_match %r|found no seed files for "test/cases/missing"|, error.message
+    end
+
+    assert_raise(Oaken::NoSeedsFoundError) { seed :first_missing, :second_missing }.tap do |error|
+      assert_match /found no seed files for "first_missing"/, error.message
+    end
+  end
 end