assert.js - truthy test function in less than 240 characters: assert(testVal1, testVal2, () => "testFunction3", ...argN) plus improvement on normal console.assert: assertMessage(test, ...messageAndSubstitutions)

assert.js

// assert.js - truthy test function in less than 240 characters: assert(testVal1, testVal2, () => "testFunction3", ...argN)
// plus improvement on normal console.assert: assertMessage(test, ...messageAndSubstitutions)
// https://gist.github.com/DarrenSem (02Nov2022 141pm)
// plus (94 characters) assert_SIMPLEST_no_messages(testVal1, testVal2, () => "testFunction3")
// OR (138 characters) assert_SIMPLEST_with_messages_via_optional_array(testVal1, [testVal2, "msg2a", "msg2b"], [() => "testFunction3", "msg3"])



// 138 char	let assert=(...t)=>!!t.reduce((p,f,i,a,m=Array.isArray(f)?f:[f])=>("function"==typeof m[0]?m[0]():m[0])?p:console.assert(0,...m),t.length)
let assert_SIMPLEST_with_messages_via_optional_array = (...tests) => !!tests.reduce(
	(pass, func, i, ar, messages = Array.isArray(func) ? func : [func]) => (
		typeof messages[0] === "function" ? messages[0]() : messages[0]
	) ? pass : console.assert(0, ...messages)
	, tests.length
);

// 94 char	let assert=(...t)=>!!t.reduce((p,f)=>("function"==typeof f?f():f)?p:console.error(f),t.length)
let assert_SIMPLEST_no_messages = (...tests) => !!tests.reduce(
	(pass, func) => (
		typeof func === "function" ? func() : func
	) ? pass : console.error(func)	// OR... ) ? pass : console.assert(0, func)
	, tests.length
);

let assert_SIMPLEST = assert_SIMPLEST_with_messages_via_optional_array;
// let assert_SIMPLEST = assert_SIMPLEST_no_messages;

console.clear();

assert_SIMPLEST();
// false

// assert_SIMPLEST(true);
// Uncaught TypeError: z[0] is not a function

assert_SIMPLEST(() => true);
// true

assert_SIMPLEST(1 - 1);
// Assertion failed: 0
// false

console.warn("---");

let with_messages_fail = [
	() => null,
	null,
	"<< is it truthy?",
	!!null
];

assert_SIMPLEST(	// this is the ONLY different result versus "previous_gist_no_messages" version
	() => 1,
	2 - 2,
	() => 3 - 3,
	with_messages_fail
);
// Assertion failed: 0
// Assertion failed: () => 3 - 3
// Assertion failed: () => null null 'is not' 'truthy' 0
// false

console.warn("---");

console.assert(null,...with_messages_fail);
// Assertion failed: () => null null 'is not' 'truthy' 0
// undefined

console.assert(...with_messages_fail);
// undefined

console.warn("---");

let with_messages_pass = [
	() => 0.1,
	0.1,
	"<< is it truthy?",
	!!0.1
];

assert_SIMPLEST(
	() => 1,
	2 - 2,
	() => 3 - 3,
	with_messages_pass
);
// Assertion failed: 0
// Assertion failed: () => 3 - 3
// false

console.assert(0.1,...with_messages_pass);
// undefined

console.assert(...with_messages_pass);
// undefined

console.warn("---");



// (show every fail) 223 char	let assert=(...a)=>!a.reduce((b,c,d,e,f)=>(f=("function"==typeof c?!c():!c)&&[2>a.length?c:`<arg #${d+1}> ${a.map((a,b)=>`#${b+1} = [ ${a} ]`).join(" , ")}`],f&&console.assert(0,...b[b.push(f)-1]),b),a.length?[]:[a]).length

// (abort after 1st) 236 char	let assert=(...a)=>!a.reduce((b,c,d,e,f)=>(f=("function"==typeof c?!c():!c)&&(e.length=0,[2>a.length?c:`<arg #${d+1}> ${a.map((a,b)=>`#${b+1} = [ ${a} ]`).join(" , ")}`]),f&&console.assert(0,...b[b.push(f)-1]),b),a.length?[]:[a]).length

let assert = (...args) => {
	return !args.reduce((acc, value, i, ar, failureThis) => {
		failureThis = !(typeof value === "function" ? value() : value) && (
			// ar.length = 0,	// uncomment this line to ABORT_AFTER_1ST 
			[
				args.length < 2 ? value
				: `<arg #${i + 1}> ${args.map((arg, n) => `#${n + 1} = [ ${arg} ]`).join(" , ")}`	// OLD: `\t<<< #${i + 1} of ${args.length} args: ${args}`)
			]
		);
		if(failureThis) {
			console.assert(0, ...acc[acc.push(failureThis) - 1]);
		};
		return acc;
	}, args.length ? [] : [args]).length
};

// an improvement on the normal console.assert(test, message, ...substitutions)
// 62 char	let assertMessage=(t,...m)=>assert(t)||console.error(...m)||!1
let assertMessage = (test, ...messageAndSubstitutions) => assert(test) || console.error(...messageAndSubstitutions) || false;



// console.clear();

assert(9)
// true

assert()
// false

assert(9  -  9)
// VM456:11 Assertion failed: 0
// (anonymous) @ VM456:11
// assert @ VM456:2
// (anonymous) @ VM123:1
// false

assert(() => 9  -  9)
// VM456:11 Assertion failed: () => 9  -  9
// (anonymous) @ VM456:11
// assert @ VM456:2
// (anonymous) @ VM123:1
// false

assert(9  -  1, () => 9  -  1)
// true

assert(9  -  1, () => 9  -  9, () => 9  -  1, 9  -  9)
// VM456:12 Assertion failed: <arg #2> #1 = [ 8 ] , #2 = [ () => 9  -  9 ] , #3 = [ () => 9  -  1 ] , #4 = [ 0 ]
// (anonymous) @ VM456:12
// assert @ VM456:3
// (anonymous) @ VM123:1
// VM456:12 Assertion failed: <arg #4> #1 = [ 8 ] , #2 = [ () => 9  -  9 ] , #3 = [ () => 9  -  1 ] , #4 = [ 0 ]
// (anonymous) @ VM456:12
// assert @ VM456:3
// (anonymous) @ VM123:1
// false



console.assert(() => 9  -  1, "is %c9 minus 1%c truthy%c1???", "color: blue;", "color: green", "???")
// undefined returned, but "truthy" AKA not failure because it did not execute as a FUNCTION: () => 9  -  9
// true

assertMessage(() => 9  -  1, "is %c9 minus 1%c truthy%c2???", "color: blue;", "color: green", "???")
// true



console.assert(9  -  9, "is %c9 minus 9%c truthy%c#3???", "color: blue;", "color: green", "???")
// VM123:1 Assertion failed: is 9 minus 9 truthy#3???
// (anonymous) @ VM123:1
// undefined

console.assert(() => 9  -  9, "is %c9 minus 9%c truthy%c#4???", "color: blue;", "color: green", "???")
// undefined returned, but "truthy" AKA not failure because it did not execute as a FUNCTION: () => 9  -  9

assertMessage(() => 9  -  9, "is %c9 minus 9%c truthy%c#5???", "color: blue;", "color: green", "???")
// VM456:12 Assertion failed: () => 9  -  9
// (anonymous) @ VM456:12
// assert @ VM456:3
// assertMessage @ VM456:19
// (anonymous) @ VM123:1
// VM456:19 is 9 minus 9 truthy#5???
// assertMessage @ VM456:19
// (anonymous) @ VM123:1
// false

let assert_SIMPLEST = (...tests) => !!tests.reduce((pass, func) => (typeof func === "function" ? func() : func) ? pass : console.error(func), tests.length);
could also be...
let assert_SIMPLEST = (...tests) => !!tests.reduce((pass, func) => (typeof func === "function" ? func() : func) ? pass : console.assert(false, func), tests.length);
...for a red error message saying "Assertion failed: () => 123 - 123" rather than just "() => 123 - 123"