Translate exceptions in filters to Liquid::FilterError errors.

lib/liquid/errors.rb

@@ -49,6 +49,10 @@ module Liquid
     end
   end
 
+  class FilterError < Error
+    attr_accessor :original_exception
+  end
+
   ArgumentError = Class.new(Error)
   ContextError = Class.new(Error)
   FileSystemError = Class.new(Error)

lib/liquid/strainer.rb

@@ -47,12 +47,20 @@ module Liquid
 
     def invoke(method, *args)
       if self.class.invokable?(method)
-        send(method, *args)
+        begin
+          send(method, *args)
+        rescue ::ArgumentError => e
+          raise Liquid::ArgumentError.new(e.message)
+        rescue Liquid::Error
+          raise
+        rescue ::StandardError => exception
+          error = Liquid::FilterError.new(exception.message)
+          error.original_exception = exception
+          raise error
+        end
       else
         args.first
       end
-    rescue ::ArgumentError => e
-      raise Liquid::ArgumentError.new(e.message)
     end
   end
 end

test/integration/filter_test.rb

@@ -22,6 +22,12 @@ module SubstituteFilter
   end
 end
 
+module ErrorFilter
+  def standard_error(input)
+    raise ::StandardError, 'standard error'
+  end
+end
+
 class FiltersTest < Minitest::Test
   include Liquid
 
@@ -158,7 +164,14 @@ class FiltersInTemplate < Minitest::Test
     assert_equal " 1000$ CAD ", Template.parse("{{1000 | money}}").render!(nil, CanadianMoneyFilter)
     assert_equal " 1000$ CAD ", Template.parse("{{1000 | money}}").render!(nil, [CanadianMoneyFilter])
   end
-end # FiltersTest
+
+  def test_filter_error
+    context = Context.new
+    context.add_filters(ErrorFilter)
+    assert_equal "Liquid error: standard error", Template.parse("{{'var' | standard_error}}").render(context)
+    assert_equal [Liquid::FilterError], context.errors.map(&:class)
+  end
+end
 
 class TestObject
   attr_accessor :a

test/integration/template_test.rb

@@ -201,14 +201,16 @@ class TemplateTest < Minitest::Test
   def test_exception_handler_doesnt_reraise_if_it_returns_false
     exception = nil
     Template.parse("{{ 1 | divided_by: 0 }}").render({}, exception_handler: ->(e) { exception = e; false })
-    assert exception.is_a?(ZeroDivisionError)
+    assert exception.is_a?(Liquid::FilterError)
+    assert exception.original_exception.is_a?(ZeroDivisionError)
   end
 
   def test_exception_handler_does_reraise_if_it_returns_true
     exception = nil
-    assert_raises(ZeroDivisionError) do
+    assert_raises(Liquid::FilterError) do
       Template.parse("{{ 1 | divided_by: 0 }}").render({}, exception_handler: ->(e) { exception = e; true })
     end
-    assert exception.is_a?(ZeroDivisionError)
+    assert exception.is_a?(Liquid::FilterError)
+    assert exception.original_exception.is_a?(ZeroDivisionError)
   end
 end