closes #57 added assert element exists (#59)

* closes #57 added assert element exists

README.md

@@ -205,9 +205,12 @@ will replace the `.text` attribute with the provided `text`.
 
 ##### faketorio.find_element_by_id(id, player)
 
-Returns a [gui element](http://lua-api.factorio.com/latest/LuaGuiElement.html) with the given `id` for the given `player`.
+Returns a [gui element](http://lua-api.factorio.com/latest/LuaGuiElement.html) with the given `id` for the given `player` or `nil if element does not exist.
 Both parameters are mandatory.
 
+##### faketorio.ensure_element_exists(id, player)
+
+Like `find_element_by_id` but will fail if element is not found.
 
 #### logging
 

build.sh

@@ -5,7 +5,7 @@ set -e
 rm -f luacov.*.out
 
 luacheck src spec
-busted -c
+busted -c -v
 
 echo "Checking where we should deploy or not. Tag is ${TRAVIS_TAG}, branch is ${TRAVIS_BRANCH} and pull request is ${TRAVIS_PULL_REQUEST}".
 if [ -n "${TRAVIS_TAG}" ] ; then

spec/ingame_spec.lua

@@ -194,6 +194,25 @@ describe("Test feature/scenario registration #ingame", function()
         assert.are.equals("wololo", element.text)
     end)
 
+    it("should find an existing element.", function ()
+        local byId = faketorio.find_element_by_id("testId", game.players[1])
+        assert.are.equals("testId", byId.name, "find by id failed.")
+
+        local assert_exists = faketorio.assert_element_exists("testId", game.players[1])
+        assert.are.equals("testId", assert_exists.name, "assert exists failed.")
+    end)
+
+    it("should work for non existing element.", function ()
+        local element = faketorio.find_element_by_id("testId222", game.players[1])
+        assert.are.equals(nil, element)
+    end)
+
+    it("should fail for asserting non existing elements.", function ()
+        local result, error = pcall(faketorio.assert_element_exists,"testId222", game.players[1])
+        assert.False(result)
+        assert.is_Truthy(error)
+    end)
+
     it("should fail to enter text on invalid element type.", function()
         assert.has_errors(function() faketorio.enter_text("someOtherId", "shouldFail") end)
     end)

src/ingame/functions.lua

@@ -145,6 +145,13 @@ function faketorio.enter_text(id, text)
     element.text = text
 end
 
+function faketorio.assert_element_exists(id, player)
+    local element = faketorio.find_element_by_id(id, player)
+    local error = string.format("Could not find element with id [%s] for player [%s].", id, player.name)
+    assert(element ~= nil, debug.traceback(error))
+    return element
+end
+
 function faketorio.find_element_by_id(id, player)
 
     faketorio.log.trace("Starting find by id for id [%s] and player [%s].", {id, player.name})
@@ -164,7 +171,7 @@ function faketorio.find_element_by_id(id, player)
         end
     end
 
-    error(debug.traceback(string.format("Could not find element with id [%s] for player [%s].", id, player.name)))
+    return nil
 end
 
 function faketorio.do_find_element_by_id(id, element)