Avoid using the shell to locate wkhtmltopdf in a Bundler environment

lib/wicked_pdf.rb

@@ -336,7 +336,7 @@ def find_wkhtmltopdf_binary_path
     possible_locations += %w[~/bin] if ENV.key?('HOME')
     exe_path ||= WickedPdf.config[:exe_path] unless WickedPdf.config.empty?
     exe_path ||= begin
-      detected_path = (defined?(Bundler) ? `bundle exec which wkhtmltopdf` : `which wkhtmltopdf`).chomp
+      detected_path = (defined?(Bundler) ? Bundler.which('wkhtmltopdf') : `which wkhtmltopdf`).chomp
       detected_path.present? && detected_path
     rescue StandardError
       nil

test/unit/wkhtmltopdf_location_test.rb

@@ -0,0 +1,50 @@
+
+
+class WkhtmltopdfLocationTest < ActiveSupport::TestCase
+  setup do
+    @saved_config = WickedPdf.config
+    WickedPdf.config = {}
+  end
+
+  teardown do
+    WickedPdf.config = @saved_config
+  end
+
+  test 'should correctly locate wkhtmltopdf without bundler' do
+    bundler_module = Bundler
+    Object.send(:remove_const, :Bundler)
+
+    assert_nothing_raised do
+      WickedPdf.new
+    end
+
+    Object.const_set(:Bundler, bundler_module)
+  end
+
+  test 'should correctly locate wkhtmltopdf with bundler' do
+    assert_nothing_raised do
+      WickedPdf.new
+    end
+  end
+
+  class LocationNonWritableTest < ActiveSupport::TestCase
+    setup do
+      @saved_config = WickedPdf.config
+      WickedPdf.config = {}
+
+      @old_home = ENV['HOME']
+      ENV['HOME'] = '/not/a/writable/directory'
+    end
+
+    teardown do
+      WickedPdf.config = @saved_config
+      ENV['HOME'] = @old_home
+    end
+
+    test 'should correctly locate wkhtmltopdf with bundler while HOME is set to a non-writable directory' do
+      assert_nothing_raised do
+        WickedPdf.new
+      end
+    end
+  end
+end