Improved assert messages for certain expressions.

assert-gooder.lua

@@ -1,9 +1,6 @@
 
 local lexer = require 'lua_lang'
 
---------------------------------------------------------------------------------
-
-
 --------------------------------------------------------------------------------
 
 local function get_assert_body_text (call_info)
@@ -72,6 +69,57 @@ local function get_value_of_string (string_str)
 	assert(false)
 end
 
+local function fmt_val (val)
+	if type(val) == 'string' then
+		return string.format('%q', val)
+	else
+		return tostring(val)
+	end
+end
+
+local function get_variable_and_prefix (gotten_name, level)
+	assert(type(gotten_name) == 'string')
+	assert(type(level) == 'number')
+	--
+	local gotten_val, var_scope, in_func  =  get_variable(gotten_name, level + 1)
+	local func_name = (in_func == '' and ' to anonymous function') or in_func and (' to \''..in_func..'\'') or ''
+	return gotten_val, ('assertion failed! bad %s \'%s\'%s'):format(var_scope, gotten_name, func_name)
+end
+
+
+local CONSTANT_VALUE_TOKEN = {
+	NUMBER	= tonumber,
+	STRING	= get_value_of_string,
+	TRUE  	= function() return true 	end,
+	FALSE 	= function() return false	end,
+	NIL   	= function() return nil  	end
+}
+
+local PRIMITIVE_VALUES = {
+	['nil']    	= true,
+	['boolean']	= true,
+}
+
+local COMPLEX_TYPES = {
+	['table']   	= true,
+	['userdata']	= true,
+	['cdata']   	= true,
+}
+
+local function get_value_of_const_token (token)
+	assert(CONSTANT_VALUE_TOKEN[token.token])
+	return CONSTANT_VALUE_TOKEN[token.token](token.text)
+end
+
+local function fmt_with_type (val)
+	-- Primitive values ARE their type, and don't need the annotation.
+	if PRIMITIVE_VALUES[type(val)] then  return tostring(val)  end
+	-- Complex types are already formatted with some type information.
+	if COMPLEX_TYPES[type(val)] then  return tostring(val)  end
+	-- Numbers and string should have their types with them.
+	return type(val) .. ' ' .. fmt_val(val)
+end
+
 --------------------------------------------------------------------------------
 
 return function (condition)
@@ -79,12 +127,27 @@ return function (condition)
 	local call_info = debug.getinfo(2)
 	local tokens, body_text = get_assert_body(call_info)
 
-	if tokens[1].text == 'type' and tokens[2].token == 'LPAR' and tokens[3].token == 'IDENTIFIER' and tokens[4].token == 'RPAR'and tokens[5].token == 'EQ'and tokens[6].token == 'STRING' then
+	if #tokens == 6 and tokens[1].text == 'type' and tokens[2].token == 'LPAR' and tokens[3].token == 'IDENTIFIER' and tokens[4].token == 'RPAR'and tokens[5].token == 'EQ'and tokens[6].token == 'STRING' then
-		local var_name = tokens[3].text
+		local gotten_val, prefix  =  get_variable_and_prefix(tokens[3].text, 2)
-		local var_val, var_scope, is_func  =  get_variable(var_name, 2)
+		error(('%s (%s expected, but got %s: %s)'):format(prefix, get_value_of_string(tokens[6].text), type(gotten_val), fmt_val(gotten_val)), 2)
-		local func_name = (is_func == '' and ' to anonymous function') or is_func and (' to \''..is_func..'\'') or ''
+	elseif #tokens == 3 and tokens[1].token == 'IDENTIFIER' and tokens[2].token == 'EQ' and CONSTANT_VALUE_TOKEN[tokens[3].token] then
-		error(('assertion failed! bad %s \'%s\'%s (%s expected, but got %s: %s)'):format(var_scope, var_name, func_name, get_value_of_string(tokens[6].text), type(var_val), var_val), 2)
+		local gotten_val, prefix  =  get_variable_and_prefix(tokens[1].text, 2)
+
+		local expected_value = get_value_of_const_token(tokens[3])
+		local type_annotation = (type(expected_value) == type(gotten_val)) and '' or (' '..type(gotten_val))
+
+		error(('%s (%s expected, but got%s: %s)'):format(prefix, fmt_with_type(expected_value), type_annotation, fmt_val(gotten_val)), 2)
+	elseif #tokens == 3 and tokens[1].token == 'IDENTIFIER' and tokens[2].token == 'NEQ' and CONSTANT_VALUE_TOKEN[tokens[3].token] then
+		local gotten_val, prefix  =  get_variable_and_prefix(tokens[1].text, 2)
+
+		local expected_value = get_value_of_const_token(tokens[3])
+
+		error(('%s (expected anything other than %s, but got %s)'):format(prefix, fmt_with_type(expected_value), fmt_val(gotten_val)), 2)
+	elseif #tokens == 1 and tokens[1].token == 'IDENTIFIER' then
+		local gotten_val, prefix  =  get_variable_and_prefix(tokens[1].text, 2)
+		error(('%s (truthy expected, but got %s)'):format(prefix, fmt_val(gotten_val)), 2)
 	else
+		print(require'pretty'(tokens))
 		error(('assertion failed! expression `%s` evaluated to %s'):format(body_text, condition), 2)
 	end
 end

test/test_assert-gooder.lua

@@ -45,25 +45,6 @@ SUITE:addTest('argument to named function', function ()
 	assert_equal('./test/test_assert-gooder.lua:'..curline(-3)..': '..'assertion failed! bad argument #1 \'a\' to \'f\' (string expected, but got number: 2)', msg)
 end)
 
---------------------------------------------------------------------------------
--- Other assert types
-
-SUITE:addTest('compare values', function ()
-	local _, msg  =  pcall(function ()
-		local a = 2
-		assert(a == 4)
-	end)
-	assert_equal('./test/test_assert-gooder.lua:'..curline(-2)..': '..'assertion failed! bad local \'a\' (value of 4 expected, but got: 2)', msg)
-end)
-
-SUITE:addTest('compare values across types', function ()
-	local _, msg  =  pcall(function ()
-		local a = "hi"
-		assert(a == 4)
-	end)
-	assert_equal('./test/test_assert-gooder.lua:'..curline(-2)..': '..'assertion failed! bad local \'a\' (value of 4 expected, but got string: "hi")', msg)
-end)
-
 --------------------------------------------------------------------------------
 
 SUITE:addTest('can improve asserts in loaded strings too', function ()
@@ -80,6 +61,52 @@ SUITE:addTest('really complicated expression', function ()
 	assert_equal('./test/test_assert-gooder.lua:'..curline(-3)..': '..'assertion failed! expression `a == 3 and math.floor(2.522) == 2 or 5 == n` evaluated to false', msg)
 end)
 
+--------------------------------------------------------------------------------
+-- Other assert types
+
+SUITE:addTest('compare values', function ()
+	local _, msg  =  pcall(function ()
+		local a = 2
+		assert(a == 4)
+	end)
+	assert_equal('./test/test_assert-gooder.lua:'..curline(-2)..': '..'assertion failed! bad local \'a\' (number 4 expected, but got: 2)', msg)
+end)
+
+SUITE:addTest('compare values across types', function ()
+	local _, msg  =  pcall(function ()
+		local a = "hi"
+		assert(a == 4)
+	end)
+	assert_equal('./test/test_assert-gooder.lua:'..curline(-2)..': '..'assertion failed! bad local \'a\' (number 4 expected, but got string: "hi")', msg)
+end)
+
+SUITE:addTest('is nil', function ()
+	local _, msg  =  pcall(function ()
+		local a = "hi"
+		assert(a == nil)
+	end)
+	assert_equal('./test/test_assert-gooder.lua:'..curline(-2)..': '..'assertion failed! bad local \'a\' (nil expected, but got string: "hi")', msg)
+end)
+
+SUITE:addTest('truthy', function ()
+	local _, msg  =  pcall(function ()
+		local a = false
+		assert(a)
+	end)
+	assert_equal('./test/test_assert-gooder.lua:'..curline(-2)..': '..'assertion failed! bad local \'a\' (truthy expected, but got false)', msg)
+end)
+
+SUITE:addTest('not equal', function (constant_value, msg_in_pars)
+	local func = loadstring (("return function()                            local a = %s; assert(a ~= %s)  end"):format(constant_value, constant_value)) ()
+	local _, msg = pcall(setfenv(func, getfenv()))
+	assert_equal('[string "return function()                            ..."]:1: assertion failed! bad local \'a\' ('..msg_in_pars..')', msg)
+end, { data = {
+	{ 'true' ,	'expected anything other than true, but got true' },
+	{ 'nil',  	'expected anything other than nil, but got nil' },
+	{ '"hi"', 	'expected anything other than string "hi", but got "hi"' },
+	{ '42',   	'expected anything other than number 42, but got 42' },
+}})
+
 --------------------------------------------------------------------------------
 
 return SUITE