UnitTests provides a unit test facility that can be used by other scripts using require. See Wikipedia:Lua#Unit_testing for details. The following is a sample from Module:Example/testcases:

-- Unit tests for [[Module:Example]]. Click talk page to run tests.
local p = require('Module:UnitTests')

function p:test_hello()
    self:preprocess_equals('<strong class="error"><span class="scribunto-error mw-scribunto-error-86763ef2">Script error: No such module &quot;Example&quot;.</span></strong>', 'Hello World!')
end

return p

The talk page Module talk:Example/testcases executes it with {{#invoke: Example/testcases | run_tests}}. Test methods like test_hello above must begin with "test".

run_tests

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  • run_tests: Runs all tests. Normally used on talk page of unit tests.
    {{#invoke:Example/testcases|run_tests}}
  • If differs_at is specified, a column will be added showing the first character position where the expected and actual results differ.
    {{#invoke:Example/testcases|run_tests|differs_at=1}}
    {{#invoke:Example/testcases|run_tests|highlight=1}}
  • If live_sandbox is specified, the header will show the columns "Test", "Live", "Sandbox", "Expected". This is required when using the preprocess_equals_sandbox_many method.

preprocess_equals

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  • preprocess_equals(text, expected, options): Gives a piece of wikitext to preprocess and an expected resulting value. Scripts and templates can be invoked in the same manner they would be in a page.
    self:preprocess_equals('{{#invoke:Example | hello}}', 'Hello, world!', {nowiki=1})

preprocess_equals_many

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  • preprocess_equals_many(prefix, suffix, cases, options): Performs a series of preprocess_equals() calls on a set of given pairs. Automatically adds the given prefix and suffix to each text.
    self:preprocess_equals_many('{{#invoke:Example | hello_to |', '}}', {
        {'John', 'Hello, John!'},
        {'Jane', 'Hello, Jane!'},
    }, {nowiki=1})

preprocess_equals_preprocess

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  • preprocess_equals_preprocess(text, expected, options): Gives two pieces of wikitext to preprocess and determines if they produce the same value. Useful for comparing scripts to existing templates.
    self:preprocess_equals_preprocess('{{#invoke:Example | hello}}', '{{Hello}}', {nowiki=1})

preprocess_equals_preprocess_many

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  • preprocess_equals_preprocess_many(prefix1, suffix1, prefix2, suffix2, cases, options): Performs a series of preprocess_equals_preprocess() calls on a set of given pairs. The prefix/suffix supplied for both arguments is added automatically. If in any case the second part is not specified, the first part will be used.
    self:preprocess_equals_preprocess_many('{{#invoke:ConvertNumeric | numeral_to_english|', '}}', '{{spellnum', '}}', {
        {'2'}, -- equivalent to {'2','2'},
        {'-2', '-2.0'},
    }, {nowiki=1})

preprocess_equals_sandbox_many

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  • preprocess_equals_sandbox_many(module, function, cases, options): Performs a series of preprocess_equals_compare() calls on a set of given pairs. The test compares the live version of the module vs the /sandbox version and vs an expected result. Ensure live_sandbox is specified or there may be some errors in the output.
    self:preprocess_equals_sandbox_many('{{#invoke:Example', 'hello_to', {
        {'John', 'Hello, John!'},
        {'Jane', 'Hello, Jane!'},
    }, {nowiki=1})
  • equals(name, actual, expected, options): Gives a computed value and the expected value, and checks if they are equal according to the == operator. Useful for testing modules that are designed to be used by other modules rather than using #invoke.
    self:equals('Simple addition', 2 + 2, 4, {nowiki=1})

equals_deep

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  • equals_deep(name, actual, expected, options): Like equals, but handles tables by doing a deep comparison. Neither value should contain circular references, as they are not handled by the current implementation and may result in an infinite loop.
    self:equals_deep('Table comparison', createRange(1,3), {1,2,3}, {nowiki=1})

Test options

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These are the valid options that can be passed into the options parameters of the test functions listed above.

Enabling this wraps the output text in <nowiki>...</nowiki> tags to avoid the text being rendered (E.g. <span>[[Example|Page]]</span> instead of Page)

combined

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Enabling this will display the output text in both the rendered mode and the nowiki mode to allow for both a raw text and visual comparison.

templatestyles

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Enabling this fixes the IDs in the strip markers <templatestyles>...</templatestyles> produces when processed to avoid incorrectly failing the tests.

stripmarker

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Enabling this fixes the IDs in all strip markers produces when processed to avoid incorrectly failing the tests.

An optional function that changes how the output from the tests are displayed. This doesn't effect the comparison process.

See also

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-- UnitTester provides unit testing for other Lua scripts. For details see [[Wikipedia:Lua#Unit_testing]].
-- For user documentation see talk page.
local UnitTester = {}

local frame, tick, cross, should_highlight
local result_table_header = "{|class=\"wikitable unit-tests-result\"\n|+ %s\n! !! Text !! Expected !! Actual"
local result_table_live_sandbox_header = "{|class=\"wikitable unit-tests-result\"\n|+ %s\n! !! Test !! Live !! Sandbox !! Expected"

local result_table = { n = 0 }
local result_table_mt = {
	insert = function (self, ...)
		local n = self.n
		for i = 1, select('#', ...) do
			local val = select(i, ...)
			if val ~= nil then
				n = n + 1
				self[n] = val
			end
		end
		self.n = n
	end,
	insert_format = function (self, ...)
		self:insert(string.format(...))
	end,
	concat = table.concat
}
result_table_mt.__index = result_table_mt
setmetatable(result_table, result_table_mt)

local num_failures = 0
local num_runs = 0

local function first_difference(s1, s2)
	s1, s2 = tostring(s1), tostring(s2)
    if s1 == s2 then return '' end
    local max = math.min(#s1, #s2)
    for i = 1, max do
        if s1:sub(i,i) ~= s2:sub(i,i) then return i end
    end
    return max + 1
end

local function return_varargs(...)
	return ...
end

function UnitTester:calculate_output(text, expected, actual, options)
	-- Set up some variables for throughout for ease
	num_runs = num_runs + 1
	local options = options or {}
	
	-- Fix any stripmarkers if asked to do so to prevent incorrect fails
	local compared_expected = expected
	local compared_actual = actual
	if options.templatestyles then
		local pattern = '(\127[^\127]*UNIQ%-%-templatestyles%-)(%x+)(%-QINU[^\127]*\127)'
		local _, expected_stripmarker_id = compared_expected:match(pattern)				-- when module rendering has templatestyles strip markers, use ID from expected to prevent false test fail
		if expected_stripmarker_id then
			compared_actual = compared_actual:gsub(pattern, '%1' .. expected_stripmarker_id .. '%3')	-- replace actual id with expected id; ignore second capture in pattern
			compared_expected = compared_expected:gsub(pattern, '%1' .. expected_stripmarker_id .. '%3')		-- account for other strip markers
		end
	end
	if options.stripmarker then
		local pattern = '(\127[^\127]*UNIQ%-%-%l+%-)(%x+)(%-%-?QINU[^\127]*\127)'
		local _, expected_stripmarker_id = compared_expected:match(pattern)
		if expected_stripmarker_id then
			compared_actual = compared_actual:gsub(pattern, '%1' .. expected_stripmarker_id .. '%3')
			compared_expected = compared_expected:gsub(pattern, '%1' .. expected_stripmarker_id .. '%3')
		end
	end
	
	-- Perform the comparison
	local success = compared_actual == compared_expected
	if not success then
		num_failures = num_failures + 1
	end
	
	-- Sort the wikitext for displaying the results
	if options.combined then
		-- We need 2 rows available for the expected and actual columns
		-- Top one is parsed, bottom is unparsed
		local differs_at = self.differs_at and (' \n| rowspan=2|' .. first_difference(compared_expected, compared_actual)) or ''
		-- Local copies of tick/cross to allow for highlighting
		local highlight = (should_highlight and not success and 'style="background:#fc0;" ') or ''
		result_table:insert(													-- Start output
			'| ', highlight, 'rowspan=2|', success and tick or cross,			-- Tick/Cross (2 rows)
			' \n| rowspan=2|', mw.text.nowiki(text), ' \n| ',					-- Text used for the test (2 rows)
			expected, ' \n| ', actual,											-- The parsed outputs (in the 1st row)
			differs_at, ' \n|-\n| ',											-- Where any relevant difference was (2 rows)
			mw.text.nowiki(expected), ' \n| ', mw.text.nowiki(actual),			-- The unparsed outputs (in the 2nd row)
			'\n|-\n'															-- End output
		)
	else
		-- Display normally with whichever option was preferred (nowiki/parsed)
		local differs_at = self.differs_at and (' \n| ' .. first_difference(compared_expected, compared_actual)) or ''
		local formatting = options.nowiki and mw.text.nowiki or return_varargs
		local highlight = (should_highlight and not success and 'style="background:#fc0;"|') or ''
		result_table:insert(													-- Start output
			'| ', highlight, success and tick or cross,							-- Tick/Cross
			' \n| ', mw.text.nowiki(text), ' \n| ',								-- Text used for the test
			formatting(expected), ' \n| ', formatting(actual),					-- The formatted outputs
			differs_at,															-- Where any relevant difference was
			'\n|-\n'															-- End output
		)
	end
end

function UnitTester:preprocess_equals(text, expected, options)
    local actual = frame:preprocess(text)
    self:calculate_output(text, expected, actual, options)
end

function UnitTester:preprocess_equals_many(prefix, suffix, cases, options)
    for _, case in ipairs(cases) do
        self:preprocess_equals(prefix .. case[1] .. suffix, case[2], options)
    end
end

function UnitTester:preprocess_equals_preprocess(text1, text2, options)
	local actual = frame:preprocess(text1)
	local expected = frame:preprocess(text2)
	self:calculate_output(text1, expected, actual, options)
end

function UnitTester:preprocess_equals_compare(live, sandbox, expected, options)
	local live_text = frame:preprocess(live)
	local sandbox_text = frame:preprocess(sandbox)
	local highlight_live = false
	local highlight_sandbox = false
	num_runs = num_runs + 1
	if live_text == expected and sandbox_text == expected then
		result_table:insert('| ', tick)
	else
		result_table:insert('| ', cross)
		num_failures = num_failures + 1

		if live_text ~= expected then
			highlight_live = true
		end

		if sandbox_text ~= expected then
			highlight_sandbox = true
		end
	end
    local formatting = (options and options.nowiki and mw.text.nowiki) or return_varargs
    local differs_at = self.differs_at and (' \n| ' .. first_difference(expected, live_text) or first_difference(expected, sandbox_text)) or ''
    result_table:insert(
			' \n| ',
			mw.text.nowiki(live),
			should_highlight and highlight_live and ' \n|style="background: #fc0;"| ' or ' \n| ',
			formatting(live_text),
			should_highlight and highlight_sandbox and ' \n|style="background: #fc0;"| ' or ' \n| ',
			formatting(sandbox_text),
			' \n| ',
			formatting(expected),
			differs_at,
			"\n|-\n"
	)
end

function UnitTester:preprocess_equals_preprocess_many(prefix1, suffix1, prefix2, suffix2, cases, options)
    for _, case in ipairs(cases) do
        self:preprocess_equals_preprocess(prefix1 .. case[1] .. suffix1, prefix2 .. (case[2] and case[2] or case[1]) .. suffix2, options)
    end
end

function UnitTester:preprocess_equals_sandbox_many(module, function_name, cases, options)
    for _, case in ipairs(cases) do
		local live = module .. "|" .. function_name .. "|" .. case[1] .. "}}"
		local sandbox = module .. "/sandbox|" .. function_name .. "|" .. case[1] .. "}}"
        self:preprocess_equals_compare(live, sandbox, case[2], options)
    end
end

function UnitTester:equals(name, actual, expected, options)
	num_runs = num_runs + 1
    if actual == expected then
        result_table:insert('| ', tick)
    else
        result_table:insert('| ', cross)
        num_failures = num_failures + 1
    end
    local formatting = (options and options.nowiki and mw.text.nowiki) or return_varargs
    local differs_at = self.differs_at and (' \n| ' .. first_difference(expected, actual)) or ''
    local display = options and options.display or return_varargs
    result_table:insert(' \n| ', name, ' \n| ',
    	formatting(tostring(display(expected))), ' \n| ',
    	formatting(tostring(display(actual))), differs_at, "\n|-\n")
end

local function deep_compare(t1, t2, ignore_mt)
    local ty1 = type(t1)
    local ty2 = type(t2)
    if ty1 ~= ty2 then return false end
    if ty1 ~= 'table' and ty2 ~= 'table' then return t1 == t2 end

    local mt = getmetatable(t1)
    if not ignore_mt and mt and mt.__eq then return t1 == t2 end

    for k1, v1 in pairs(t1) do
        local v2 = t2[k1]
        if v2 == nil or not deep_compare(v1, v2) then return false end
    end
    for k2, v2 in pairs(t2) do
        local v1 = t1[k2]
        if v1 == nil or not deep_compare(v1, v2) then return false end
    end

    return true
end

local function val_to_str(obj)
    local function table_key_to_str(k)
        if type(k) == 'string' and mw.ustring.match(k, '^[_%a][_%a%d]*$') then
            return k
        else
            return '[' .. val_to_str(k) .. ']'
        end
    end

    if type(obj) == "string" then
        obj = mw.ustring.gsub(obj, "\n", "\\n")
        if mw.ustring.match(mw.ustring.gsub(obj, '[^\'"]', ''), '^"+$') then
            return "'" .. obj .. "'"
        end
        return '"' .. mw.ustring.gsub(obj, '"', '\\"' ) .. '"'

    elseif type(obj) == "table" then
        local result, checked = {}, {}
        for k, v in ipairs(obj) do
            table.insert(result, val_to_str(v))
            checked[k] = true
        end
        for k, v in pairs(obj) do
            if not checked[k] then
                table.insert(result, table_key_to_str(k) .. '=' .. val_to_str(v))
            end
        end
        return '{' .. table.concat(result, ',') .. '}'

    else
        return tostring(obj)
    end
end

function UnitTester:equals_deep(name, actual, expected, options)
	num_runs = num_runs + 1
    if deep_compare(actual, expected) then
        result_table:insert('| ', tick)
    else
        result_table:insert('| ', cross)
        num_failures = num_failures + 1
    end
    local formatting = (options and options.nowiki and mw.text.nowiki) or return_varargs
    local actual_str = val_to_str(actual)
    local expected_str = val_to_str(expected)
    local differs_at = self.differs_at and (' \n| ' .. first_difference(expected_str, actual_str)) or ''
    result_table:insert(' \n| ', name, ' \n| ', formatting(expected_str),
    	' \n| ', formatting(actual_str), differs_at, "\n|-\n")
end

function UnitTester:iterate(examples, func)
	require 'libraryUtil'.checkType('iterate', 1, examples, 'table')
	if type(func) == 'string' then
		func = self[func]
	elseif type(func) ~= 'function' then
		error(("bad argument #2 to 'iterate' (expected function or string, got %s)")
			:format(type(func)), 2)
	end

	for i, example in ipairs(examples) do
		if type(example) == 'table' then
			func(self, unpack(example))
		elseif type(example) == 'string' then
			self:heading(example)
		else
			error(('bad example #%d (expected table, got %s)')
				:format(i, type(example)), 2)
		end
	end
end

function UnitTester:heading(text)
	result_table:insert_format(' ! colspan="%u" style="text-align: left" | %s \n |- \n ',
		self.columns, text)
end

function UnitTester:run(frame_arg)
    frame = frame_arg
    self.frame = frame
    self.differs_at = frame.args['differs_at']
    tick = frame:preprocess('{{Tick}}')
    cross = frame:preprocess('{{Cross}}')

	local table_header = result_table_header
	if frame.args['live_sandbox'] then
		table_header = result_table_live_sandbox_header
	end
	if frame.args.highlight then
		should_highlight = true
	end

	self.columns = 4
    if self.differs_at then
        table_header = table_header .. ' !! Differs at'
        self.columns = self.columns + 1
    end

    -- Sort results into alphabetical order.
    local self_sorted = {}
    for key, _ in pairs(self) do
        if key:find('^test') then
            table.insert(self_sorted, key)
        end
    end
    table.sort(self_sorted)
    -- Add results to the results table.
    for _, value in ipairs(self_sorted) do
        result_table:insert_format(table_header .. "\n|-\n", value)
        self[value](self)
        result_table:insert("|}\n")
    end

    return (num_runs == 0 and "<b>No tests were run.</b>"
    	or num_failures == 0 and "<b style=\"color:#008000\">All " .. num_runs .. " tests passed.</b>"
    	or "<b style=\"color:#800000\">" .. num_failures .. " of " .. num_runs .. " tests failed.</b>[[Category:Failed Lua testcases using Module:UnitTests]]"
    ) .. "\n\n" .. frame:preprocess(result_table:concat())
end

function UnitTester:new()
    local o = {}
    setmetatable(o, self)
    self.__index = self
    return o
end

local p = UnitTester:new()
function p.run_tests(frame) return p:run(frame) end
return p