fix: #35 - Adds test for backtrace truncation

Author: bougyman

Gemfile.lock

@@ -1,7 +1,7 @@
 PATH
   remote: .
   specs:
-    leopard (0.1.7)
+    leopard (0.2.1)
       concurrent-ruby (~> 1.1)
       dry-configurable (~> 1.3)
       dry-monads (~> 1.9)

lib/leopard/errors.rb

@@ -3,6 +3,11 @@
 module Rubyists
   module Leopard
     class LeopardError < StandardError
+      def initialize(...)
+        super
+        set_backtrace(caller)
+      end
+
       def backtrace
         super[0..3] + ['... (truncated by Leopard)']
       end

test/lib/errors.rb

@@ -0,0 +1,28 @@
+# frozen_string_literal: true
+
+require 'helper'
+require 'leopard/errors'
+
+describe 'Rubyists::Leopard::Errors' do
+  def level1
+    level2
+  end
+
+  def level2
+    level3
+  end
+
+  def level3
+    raise Rubyists::Leopard::Error, 'Error boom'
+  end
+
+  it 'truncates backtrace to 5 items' do
+    err = assert_raises(Rubyists::Leopard::Error) { level1 }
+
+    bt = err.backtrace
+
+    assert_equal 5, bt.count
+    assert_equal '... (truncated by Leopard)', bt.last
+    refute(bt.any? { |line| line.include?("in 'level1'") })
+  end
+end