add error spec

Author: DannyBen

.gitattributes

@@ -1 +1,2 @@
 Runfile linguist-language=Ruby
+*.gtx linguist-language=Ruby

README.md

@@ -88,7 +88,7 @@ that is expected to be a part of the output.
 Any other line, will be treated as Ruby code and will be enclosed using ERB's 
 `<%- ... -%>` syntax.
 
-See the [example template](examples/full.rb) for additional nuances.
+See the [example template](examples/full.gtx) for additional nuances.
 
 ## Usage
 

examples/full.rb renamed to examples/full.gtx

@@ -0,0 +1,19 @@
+> first line
+> second line
+>
+
+3.times do |i|
+  > {{ " " * i * 2 }}  this is loopy {{ i }}
+end
+>
+
+if true
+  > Welcome admin
+  > WARNING: YOU HAVE ADMIN RIGHTS
+end
+
+= "hello " * 3
+
+# Fail here
+= 100 / 0
+= "hello " * 3

spec/fixtures/error.gtx

@@ -4,7 +4,7 @@
   subject { described_class.new template }
   let(:context) { double user: 'admin' }
   let(:template) { "> some output\nruby_code = 'yes'\n= ruby_code" }
-  let(:example_path) { "examples/full.rb" }
+  let(:example_path) { "examples/full.gtx" }
 
   describe 'full example' do
     subject { described_class.load_file example_path }
@@ -34,6 +34,16 @@
       expect(subject.parse context).to match_approval('gtx/parse')
     end
 
+    context "on error" do
+      subject { described_class.load_file "spec/fixtures/error.gtx" }
+
+      it "registers the correct file and line number in the backtrace" do
+        expect { subject.parse }.to raise_error(ZeroDivisionError) do |e|
+          expect(e.backtrace.first).to include "spec/fixtures/error.gtx:18"
+        end
+      end
+    end
+
     context "when a Binding object is passed instead of a regular object" do
       let(:context) do 
         module Context