Rework RSpec module with enable/disable methods

lib/active_fedora/noid/rspec.rb

@@ -1,7 +1,66 @@
-RSpec.configure do |config|
-  config.before(:suite) do
-    ActiveFedora::Noid.configure do |noid_config|
-      noid_config.minter_class = ActiveFedora::Noid::Minter::File
+module ActiveFedora::Noid
+  ##
+  # Provides a test minter conforming to the `ActiveFedora::Noid::Minter`
+  # interface for use in unit tests. The test minter is faster and avoids
+  # unexpected interactions with cleanup code commonly runs in test suites
+  # (e.g. database cleanup).
+  #
+  # Applications should reenable their production minter for integration tests
+  # when appropriate
+  #
+  # @example general use
+  #   ActiveFedora::Noid::RSpec.disable_production_minter!
+  #   # some unit tests with the test minter
+  #   ActiveFedora::Noid::RSpec.enable_production_minter!
+  #   # some integration tests with the original minter
+  #
+  # @example using a custom test minter
+  #   ActiveFedora::Noid::RSpec.disable_production_minter!(test_minter: Minter)
+  #
+  # @example use when included in RSpec config
+  #   require 'active_fedora/noid/rspec'
+  #
+  #   RSpec.configure do |config|
+  #     config.include(ActiveFedora::Noid::RSpec)
+  #   end
+  #
+  #   before(:suite) { disable_production_minter! }
+  #   after(:suite)  { enable_production_minter! }
+  #
+  module RSpec
+    DEFAULT_TEST_MINTER = ActiveFedora::Noid::Minter::File
+
+    ##
+    # Replaces the configured production minter with a test minter.
+    #
+    # @param test_minter [Class] an ActiveFedora::Noid::Minter implementation
+    #   to use as a replacement minter
+    # @return [void]
+    def disable_production_minter!(test_minter: DEFAULT_TEST_MINTER)
+      return nil if @original_minter
+
+      @original_minter = ActiveFedora::Noid.config.minter_class
+
+      ActiveFedora::Noid.configure do |noid_config|
+        noid_config.minter_class = test_minter
+      end
+
+      true
+    end
+
+    ##
+    # Re-enables the original configured minter.
+    #
+    # @return [void]
+    def enable_production_minter!
+      return nil unless @original_minter
+
+      ActiveFedora::Noid.configure do |noid_config|
+        noid_config.minter_class = @original_minter
+      end
+
+      @original_minter = nil
+      true
     end
   end
 end

spec/unit/rspec_spec.rb

@@ -0,0 +1,92 @@
+require 'active_fedora/noid/rspec'
+
+describe ActiveFedora::Noid::RSpec do
+  include described_class
+
+  let(:configured_minter) { @configured_minter }
+
+  before do
+    @configured_minter = Class.new(ActiveFedora::Noid::Minter::Base)
+    @reset_minter      = ActiveFedora::Noid.config.minter_class
+
+    ActiveFedora::Noid.configure do |noid_config|
+      noid_config.minter_class = @configured_minter
+    end
+  end
+
+  after do
+    ActiveFedora::Noid.configure do |noid_config|
+      noid_config.minter_class = @reset_minter
+    end
+  end
+
+  describe '#disable_production_minter!' do
+    it 'changes the configured minter' do
+      expect { disable_production_minter! }
+        .to change { ActiveFedora::Noid.config.minter_class }
+              .from(configured_minter)
+              .to described_class::DEFAULT_TEST_MINTER
+    end
+
+    it 'accepts custom test minter at call time' do
+      my_minter = Class.new(ActiveFedora::Noid::Minter::Base)
+
+      expect { disable_production_minter!(test_minter: my_minter) }
+        .to change { ActiveFedora::Noid.config.minter_class }
+              .from(configured_minter)
+              .to my_minter
+    end
+
+    it 'does not overwrite stored minter on second call' do
+      var_name  = :@original_minter
+
+      disable_production_minter!
+
+      expect { disable_production_minter! }
+        .not_to change { described_class.instance_variable_get(var_name) }
+
+      expect { enable_production_minter! }
+        .to change { ActiveFedora::Noid.config.minter_class }
+              .from(described_class::DEFAULT_TEST_MINTER)
+              .to configured_minter
+    end
+
+    it 'disables after reenable' do
+      disable_production_minter!
+      enable_production_minter!
+
+      expect { disable_production_minter! }
+        .to change { ActiveFedora::Noid.config.minter_class }
+              .from(configured_minter)
+              .to described_class::DEFAULT_TEST_MINTER
+    end
+  end
+
+  describe '#enable_production_minter!' do
+    it 'does nothing when already enabled' do
+      expect { enable_production_minter! }
+        .not_to change { ActiveFedora::Noid.config.minter_class }
+    end
+
+    context 'with minter disabled' do
+      before { disable_production_minter! }
+
+      it 'reenables the originally configured minter' do
+        expect { enable_production_minter! }
+          .to change { ActiveFedora::Noid.config.minter_class }
+                .from(described_class::DEFAULT_TEST_MINTER)
+                .to configured_minter
+      end
+
+      it 'enables after re-disable' do
+        enable_production_minter!
+        disable_production_minter!
+
+        expect { enable_production_minter! }
+          .to change { ActiveFedora::Noid.config.minter_class }
+                .from(described_class::DEFAULT_TEST_MINTER)
+                .to configured_minter
+      end
+    end
+  end
+end