Added tests, fixed __index, custom constructor return values, 0.1.4

test.lua

@@ -0,0 +1,246 @@
+local T = require("knife-test")
+
+-- luacheck: ignore T
+T("Given the base class", function(T)
+	local class = require("classtoi")
+
+	-- Inheritance
+	T("When subclassed with an attribute", function(T)
+		local Thing = class {
+			attribute = "thing"
+		}
+
+		T:assert(Thing.attribute == "thing", "Then the attribute should be set on the subclass")
+		T:assert(class.attribute == nil, "Then the attribute shouldn't be set on the base class'")
+
+		T:assert(class.is(Thing), "Then the subclass should be a subclass of the base class (class.is)")
+		T:assert(Thing:is(class), "Then the subclass should be a subclass of the base class (subclass:is)")
+
+		T("When the subclass is instanced", function(T)
+			local thing = Thing:new()
+
+			T:assert(thing.attribute == "thing", "Then the attribute should be kept")
+
+			T:assert(class.is(thing), "Then the object should be a subclass of the base class (class.is(object))")
+			T:assert(thing:is(class), "Then the object should be a subclass of the base class (object:is(class))")
+			T:assert(thing:is(Thing), "Then the object should be a subclass of the subclass (object:is(subclass))")
+			T:assert(Thing.is(thing), "Then the object should be a subclass of the subclass (subclass.is(object))")
+
+			T("When setting the attribute on the instance", function(T)
+				thing.attribute = "not the same thing"
+
+				T:assert(thing.attribute == "not the same thing", "Then the attribute should be set for the object")
+				T:assert(Thing.attribute == "thing", "Then the attribute should be kept for the subclass")
+			end)
+		end)
+
+		T("When the subclassed is subclassed with two parents", function(T)
+			local OtherThing = class {
+				attribute = "other thing",
+				other = true
+			}
+
+			local SubThing = Thing(OtherThing)
+
+			T:assert(SubThing.attribute == "other thing", "Then the last added parent should have priority")
+
+			local SubOtherThing = class(Thing, OtherThing)
+
+			T:assert(SubOtherThing.attribute == "thing", "Then the left-most class should have priority")
+
+			T:assert(SubThing.other and SubOtherThing.other, "Then new attribute should be always inherited")
+
+			T("When adding a method to the first subclass", function(T)
+				Thing.action = function(self, arg)
+					self.attribute = arg
+				end
+
+				T("When calling it on the first subclass", function(T)
+					Thing:action("new thing")
+
+					T:assert(Thing.attribute == "new thing", "Then it affect the first subclass")
+					T:assert(SubOtherThing.attribute == "new thing", "Then it affect children wich inherit the modified attribute")
+					T:assert(SubThing.attribute == "other thing", "Then it doesn't affect children which doesn't inherit the modified attribute")
+				end)
+
+				T("When calling it on another subclass", function(T)
+					SubOtherThing:action("new thing")
+
+					T:assert(Thing.attribute == "thing", "Then it doesn't affect the parent subclass")
+					T:assert(SubOtherThing.attribute == "new thing", "Then it affect the subclass")
+					T:assert(SubThing.attribute == "other thing", "Then it doesn't affect other subclasses")
+				end)
+			end)
+		end)
+	end)
+
+	-- Constructor
+	T("When subclassed with a constructor", function(T)
+		local Thing = class {
+			attribute = "class",
+
+			new = function(self, arg)
+				self.attribute = arg or "object"
+			end
+		}
+
+		T:assert(Thing.attribute == "class", "Then the class should not call the constructor itself")
+
+		T("When the subclass is instanced without arguments", function(T)
+			local thing = Thing:new()
+
+			T:assert(thing.attribute == "object", "Then the constructor should have been called on the object without arguments")
+			T:assert(Thing.attribute == "class", "Then the constructor should not be called on the class")
+		end)
+
+		T("When the subclass is instanced without arguments", function(T)
+			local thing = Thing:new("stuff")
+
+			T:assert(thing.attribute == "stuff", "Then the constructor should have been called on the object with arguments")
+			T:assert(Thing.attribute == "class", "Then the constructor should not be called on the class")
+		end)
+
+		T("When the subclass is subclassed and instanced with another constructor", function(T)
+			local SubThing = Thing {
+				new = function(self)
+					self.sub = true
+					Thing.new(self, "a whole new thing")
+				end
+			}
+
+			local subthing = SubThing:new()
+
+			T:assert(subthing.sub, "Then the new constructor is called on the new instance")
+			T:assert(not SubThing.sub, "Then the new constructor is not called on the class")
+
+			T:assert(subthing.attribute == "a whole new thing", "Then the parent new method was correctly accessed and called on the new instance")
+			T:assert(SubThing.attribute == "class", "Then the parent new method was not called on the class")
+		end)
+	end)
+	T("When subclassed with a constructor returning non-nil values and instanced", function(T)
+		local Thing = class {
+			new = function(self, arg)
+				return true, arg
+			end
+		}
+
+		local thing, other = Thing:new("mostly useless but cool")
+
+		T:assert(thing == true and other == "mostly useless but cool", "Then the constructor return value should be returned instead of an object")
+	end)
+
+	-- Usual metamethods
+	T("When subclassed with a metamethod", function(T)
+		local Thing = class {
+			value = 0,
+			__add = function(self, other)
+				self.value = self.value + other
+				return self
+			end
+		}
+
+		T:assert(Thing.value == 0, "Then the attribute is set on the subclass")
+
+		Thing = Thing + 5
+
+		T:assert(Thing.value == 5, "Then the metamethod is correctly called on the subclass")
+		T:assert(class.value == nil, "Then the metamethod doesn't affect the base class")
+
+		T("When the subclass is instancied", function(T)
+			local thing = Thing:new()
+			thing = thing + 5
+
+			T:assert(thing.value == 10, "Then the metamethod is correctly called on the instance")
+			T:assert(Thing.value == 5, "Then the metamethod doesn't affect the parent class")
+		end)
+	end)
+
+	-- Redefining usual special class methods
+	T("When a subclass redefine one of the default class methods", function(T)
+		local Thing = class {
+			is = function(self)
+				return "mashed potatoes"
+			end,
+
+			__call = function(self, arg)
+				return "hot potatoes with "..arg
+			end
+		}
+
+		T:assert(Thing:is(class) == true, "Then defaults methods are still used on the class")
+		T:assert(Thing():is(class) == true, "Then defaults metamethods are still used on the class")
+
+		T("When the subclass is instancied", function(T)
+			local thing = Thing:new()
+
+			T:assert(thing:is(class) == "mashed potatoes", "Then the redefined method is used on the instance")
+			T:assert(thing("melted raclette") == "hot potatoes with melted raclette", "Then the redefined metamethod is used on the instance")
+		end)
+	end)
+
+	-- Redefining __index
+	T("When subclassed with an __index metamethod", function(T)
+		local Thing = class {
+			value = "other",
+
+			__index = function(self, key)
+				if key == "attribute" then
+					return "thing"
+				elseif key == "another" then
+					return self.value
+				end
+			end
+		}
+
+		T:assert(Thing.attribute == "thing", "Then the metamethod is called as expected")
+		T:assert(Thing.value == "other", "Then attribute access still works as expected")
+		T:assert(Thing.another == "other", "Then the metamethod seems to correctly pass a class as the first argument")
+
+		T("When the subclass is instanced", function(T)
+			local thing = Thing:new()
+
+			T:assert(thing.attribute == "thing", "Then the metamethod is called as expected")
+			T:assert(thing.value == "other", "Then attribute access still works as expected")
+			T:assert(thing.another == "other", "Then the metamethod seems to correctly pass a class as the first argument")
+
+			T("When changing a value returned by the metamethod on the instance", function(T)
+				thing.value = "new thing"
+
+				T:assert(thing.another == "new thing", "Then the metamethod was correctly called with the instance as the first argument")
+			end)
+		end)
+	end)
+
+	-- Defining __inherit
+	T("When subclassed with an __inherit method", function(T)
+		local Thing = class {
+			attribute = "thing",
+			replace = false,
+			__inherit = function(self, inheritingClass)
+				inheritingClass.works = true
+				if self.replace then
+					return { attribute = "other thing" }
+				end
+			end
+		}
+
+		T:assert(Thing.works == true, "Then the __inherit method was correctly called on the class creation")
+
+		T("When subclassing the subclass", function(T)
+			Thing.works = "ok"
+			local SubThing = Thing()
+
+			T:assert(SubThing.attribute == "thing", "Then the child class still inherit the subclass")
+			T:assert(SubThing.works == true, "Then the __inherit method was correctly called on the inheriting class")
+			T:assert(Thing.works == "ok", "Then the __inherit method was correctly called on the inherited class")
+		end)
+
+		T("When subclassing the subclass with a return value", function(T)
+			Thing.replace = true
+			local SubThing = Thing()
+
+			T:assert(SubThing.attribute == "other thing", "Then the child class inherited the return value")
+			T:assert(SubThing.works == true, "Then the __inherit method was correctly called on the inheriting class")
+		end)
+	end)
+end)