[liquid] default filter should not override false values

CHANGELOG.md

@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 ### Changed
 
 - Improve startup time by improving templating performance and caching filesystem access [PR #964](https://github.com/3scale/apicast/pull/964)
+- Liquid `default` filter now does not override `false` values [PR #964](https://github.com/3scale/apicast/pull/964)
 
 ### Fixed
 

gateway/Roverfile.lock

@@ -3,7 +3,7 @@ busted 2.0.rc12-1||testing
 dkjson 2.5-2||testing
 inspect 3.1.1-0||production
 ldoc 1.4.6-2||development
-liquid 0.1.0-1||production
+liquid 0.1.3-1||production
 ljsonschema 0.1.0-1||testing
 lua-resty-env 0.4.0-1||production
 lua-resty-execvp 0.1.1-1||production

gateway/src/apicast/cli/template.lua

@@ -120,7 +120,7 @@ function _M:interpret(str)
     end)
 
     filter_set:add_filter('default', function(value, default)
-        return value or default
+        if value == nil then return default else return value end
     end)
 
     filter_set:add_filter('starts_with', function(string, ...)

spec/cli/template_spec.lua

@@ -0,0 +1,19 @@
+local _M = require('apicast.cli.template')
+
+describe('Liquid Template', function ()
+
+  describe('default filter', function()
+    it('overrides nil values', function()
+      local str = _M:new():interpret([[{{ nothing | default: "foo" }}]])
+
+      assert.equal(str, 'foo')
+    end)
+
+    it('overrides false values', function()
+      local str = _M:new():interpret([[{{ false | default: "foo" }}]])
+
+      assert.equal(str, 'false')
+    end)
+  end)
+
+end)