From 6ebb96243be87ae65385b0b33b511118e243031a Mon Sep 17 00:00:00 2001
From: Nicolas Brousse <nicolas@pantographe.studio>
Date: Wed, 15 May 2019 19:41:45 +0200
Subject: [PATCH] Raise better error when mjml binary is not found

---
 lib/mjml.rb       |  4 ++++
 spec/mjml_spec.rb | 20 ++++++++++++++++++++
 2 files changed, 24 insertions(+)
 create mode 100644 spec/mjml_spec.rb

diff --git a/lib/mjml.rb b/lib/mjml.rb
index 281734a..ff1d163 100644
--- a/lib/mjml.rb
+++ b/lib/mjml.rb
@@ -5,6 +5,8 @@
 
 # MJML library for ruby
 module MJML
+  class BinaryNotFound < StandardError; end
+
   # Constants
   MIME_TYPE = 'text/mjml'.freeze
   EXTENSION = '.mjml'.freeze
@@ -62,6 +64,8 @@ def self.extract_executable_version
     end
 
     match.nil? ? nil : match[1]
+  rescue Errno::ENOENT => _e
+    raise BinaryNotFound, "mjml binary not found for path '#{config.bin_path}'"
   end
 
   def self.logger
diff --git a/spec/mjml_spec.rb b/spec/mjml_spec.rb
new file mode 100644
index 0000000..1f523c9
--- /dev/null
+++ b/spec/mjml_spec.rb
@@ -0,0 +1,20 @@
+require_relative 'spec_helper'
+require 'mjml'
+
+describe 'MJML' do
+  describe '#extract_executable_version' do
+    it 'should return the version if mjml is installed' do
+      MJML.extract_executable_version.must_be_instance_of String
+    end
+
+    it 'should return false for unknown feature' do
+      bin_path = MJML.config.bin_path
+      MJML.config.bin_path = '/usr/bin/env mjml-not-installed'
+
+      error = -> { MJML.extract_executable_version }.must_raise MJML::BinaryNotFound
+      error.message.must_match(/^mjml binary not found/)
+
+      MJML.config.bin_path = bin_path
+    end
+  end
+end