#117 Warning about MJML missing when using MRML

lib/mjml.rb

@@ -48,7 +48,8 @@ def self.valid_mjml_binary
                              check_for_custom_mjml_binary ||
                              check_for_yarn_mjml_binary ||
                              check_for_npm_mjml_binary ||
-                             check_for_global_mjml_binary
+                             check_for_global_mjml_binary ||
+                             check_for_mrml_binary
 
     return @@valid_mjml_binary if @@valid_mjml_binary
 
@@ -102,6 +103,13 @@ def self.check_for_global_mjml_binary
     return mjml_bin if mjml_bin.present? && check_version(mjml_bin)
   end
 
+  def self.check_for_mrml_binary
+    MRML.present?
+  rescue NameError
+    Mjml.mjml_binary_error_string = 'Couldn\'t find MRML - did you add \'mrml\' to your Gemfile?'
+    false
+  end
+
   def self.discover_mjml_bin
     logger.warn('`Mjml.discover_mjml_bin` is deprecated and has no effect anymore! ' \
                 'Please use `Mjml.mjml_binary=` to set a custom MJML binary.')

test/mjml_test.rb

@@ -119,11 +119,13 @@ class NotifierMailerTest < ActiveSupport::TestCase
     before do
       Mjml.mjml_binary = nil
       Mjml.valid_mjml_binary = nil
+      Mjml.use_mrml = nil
     end
 
     after do
       Mjml.mjml_binary = nil
       Mjml.valid_mjml_binary = nil
+      Mjml.use_mrml = nil
     end
 
     it 'can be set to a custom value with mjml_binary if version is correct' do
@@ -156,5 +158,19 @@ class NotifierMailerTest < ActiveSupport::TestCase
       assert(err.message.start_with?("MJML.mjml_binary is set to 'set by mjml_binary' " \
                                      'but MJML-Rails could not validate that it is a valid MJML binary'))
     end
+
+    it 'can use MRML and check for a valid binary' do
+      Mjml.use_mrml = true
+      Mjml.stubs(:check_for_custom_mjml_binary).returns(false)
+      Mjml.stubs(:check_for_yarn_mjml_binary).returns(false)
+      Mjml.stubs(:check_for_npm_mjml_binary).returns(false)
+      Mjml.stubs(:check_for_global_mjml_binary).returns(false)
+      expect(Mjml.valid_mjml_binary).must_equal(true)
+
+      Mjml.valid_mjml_binary = nil
+      MRML.stubs(:present?).raises(NameError)
+      assert_nil(Mjml.valid_mjml_binary)
+      expect(Mjml.mjml_binary_error_string).must_equal 'Couldn\'t find MRML - did you add \'mrml\' to your Gemfile?'
+    end
   end
 end