fix(is_in_nav): assert invalid data

When possible anyway. Directly modifying the array is unsupported.

README.md

@@ -102,13 +102,15 @@ A `table` for page information.
 | :-- | :--- | :---------- |
 | `title` | `string` | **Required**. Human readable page name. |
 | `get` | `function`, see below | **Required**. Return a flow form. |
-| `is_in_nav` | `function`, see below | **Optional**. Return true to show in the navigation, which defaults to tabs. |
+| `is_in_nav` | `function`, see below | **Optional**. Return true to show in the navigation, which defaults to tabs. If `is_in_nav` is absent, it will default to showing in the navigation. |
 | `on_enter` | `function`, see below | **Optional**. Called when the player changes pages, usually using the tabs. |
 | `on_leave` | `function`, see below | **Optional**. When leaving this page to go to another, called before other's `on_enter` |
 | | | **Optional**. Anything else you'd like to add. These other values can, of course, be accessed through the `self` value in the above callbacks as you'd expect. |
 
 ##### Page definition function args
 
+All page definition functions expect the same arguments.
+
 ```lua
 function(self, player, context)
     -- ...
@@ -121,7 +123,11 @@ end
 | `player` | Player `ObjectRef` | The player that will be shown the page. |
 | `context` | `table` | Context table. See `sway.get_or_create_context` |
 
-Return a `flow` page. Sway makes use of `flow_extras.set_wrapped_context` internally. This ensures that `flow_extras.get_context` works if you need to share code between multiple forms.
+`get` is expected to a `flow` page. Sway makes use of `flow_extras.set_wrapped_context` internally. This ensures that `flow_extras.get_context` works if you need to share code between multiple forms.
+
+`is_in_nav` is expected to return a boolean (see above).
+
+`on_enter` and `on_leave` are not expected to return anything.
 
 #### Refresh form with new changes
 

api.lua

@@ -11,6 +11,10 @@ function sway.register_page(name, def)
 	assert(type(name) == "string", "[sway] register_page: requires name to be string")
 	assert(type(def) == "table", "[sway] register_page: requires definition table to be table")
 	assert(type(def.get) == "function", "[sway] register_page: requires get inside the definition table to be function")
+	assert(
+		def.is_in_nav == nil or type(def.is_in_nav) == "function",
+		"[sway] register_page: page '" .. name .. "' is_in_nav must be nil or a fn."
+	)
 	assert(not sway.pages[name], "[sway] register_page: page '" .. name .. "' must not already be registered")
 
 	sway.pages[name] = def
@@ -29,6 +33,10 @@ function sway.override_page(name, def)
 	if type(def.get) ~= "nil" then
 		assert(type(def.get) == "function", "[sway] override_page: When overriding get, it must be a function.")
 	end
+	assert(
+		def.is_in_nav == nil or type(def.is_in_nav) == "function",
+		"[sway] override_page: page '" .. name .. "' is_in_nav must be nil or a fn."
+	)
 	minetest.log("action", "[sway] override_page: '" .. name .. "' is becoming overriden")
 	for key, value in pairs(def) do
 		page[key] = value

spec/sway_inv_spec.lua

@@ -78,7 +78,6 @@ describe("pages", function ()
 		sway.pages_ordered = {}
 	end)
 	describe("register_page", function ()
-		pending"assert when is_in_nav is not null or a function"
 		it("is a function on sway", function ()
 			assert.equal("function", type(sway.register_page))
 		end)
@@ -118,6 +117,11 @@ describe("pages", function ()
 				sway.register_page(testpagename, { get = function () end })
 			end, "[sway] register_page: page '" .. testpagename .. "' must not already be registered")
 		end)
+		it("assert when is_in_nav is not null or a function", function ()
+			assert.has_error(function ()
+				sway.register_page(testpagename, { get = function () end, is_in_nav = "A very sus string." })
+			end, "[sway] register_page: page '" .. testpagename .. "' is_in_nav must be nil or a fn.")
+		end)
 		it("inserts name into def, puts def into pages as key and pages_ordered", function ()
 			local def = { get = function () end }
 			sway.register_page(testpagename, def)
@@ -155,6 +159,12 @@ describe("pages", function ()
 				sway.override_page(testpagename, {})
 			end, "[sway] override_page: the page '" .. testpagename .. "' could not be found to override")
 		end)
+		it("assert when is_in_nav is not null or a function", function ()
+			sway.register_page(testpagename, { get = function () end })
+			assert.has_error(function ()
+				sway.override_page(testpagename, { get = function () end, is_in_nav = "A very sus string." })
+			end, "[sway] override_page: page '" .. testpagename .. "' is_in_nav must be nil or a fn.")
+		end)
 		it("logs that a page is getting overriden", function ()
 			sway.register_page(testpagename, { get = function () end })
 			fancy_stub(minetest, "log", function ()
@@ -1242,7 +1252,6 @@ describe("content functions", function ()
 					page = "nothing else"
 				})
 			end)
-			pending"sets the current_idx to the correct page"
 		end)
 		-- TODO: this should also be tested for pages that _do_ exist, but are not in the nav
 		pending"returns result of get for sway.page['404'] when page not found, and 404 is truthy"