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Assertions

L1

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Assertions1.js
#!/usr/bin/env node;
const Utils = require('./Utils');
const assert = require('assert');

const TEST_BASE = 0.9;

function exponentiation(base, powerArg) {
	assert(powerArg >= 0, "powerArg >= 0");
	let power = powerArg;
	let result = 1;
	while (power > 0) {
		result *= base;
		--power;
	}
	return result;
}

const main = async () => {
	for (let p = 10; p >= -1; --p) {
		console.log(Utils.format("{0:f} ^ {1:d} = {2:f}", TEST_BASE, p, exponentiation(TEST_BASE, p)));
	}
}
main().catch( e => { console.error(e) } );
Output
$ node Assertions1.js 0.9 ^ 10 = 0.34867844010000015 0.9 ^ 9 = 0.38742048900000015 0.9 ^ 8 = 0.43046721000000016 0.9 ^ 7 = 0.47829690000000014 0.9 ^ 6 = 0.5314410000000002 0.9 ^ 5 = 0.5904900000000002 0.9 ^ 4 = 0.6561000000000001 0.9 ^ 3 = 0.7290000000000001 0.9 ^ 2 = 0.81 0.9 ^ 1 = 0.9 0.9 ^ 0 = 1 AssertionError [ERR_ASSERTION]: powerArg >= 0 at exponentiation (/Users/rich/Desktop/Resources/pureprogrammer/js/examples/Assertions1.js:8:2) at main (/Users/rich/Desktop/Resources/pureprogrammer/js/examples/Assertions1.js:20:67) at Object.<anonymous> (/Users/rich/Desktop/Resources/pureprogrammer/js/examples/Assertions1.js:23:1) at Module._compile (node:internal/modules/cjs/loader:1256:14) at Module._extensions..js (node:internal/modules/cjs/loader:1310:10) at Module.load (node:internal/modules/cjs/loader:1119:32) at Module._load (node:internal/modules/cjs/loader:960:12) at Function.executeUserEntryPoint [as runMain] (node:internal/modules/run_main:81:12) at node:internal/main/run_main_module:23:47 { generatedMessage: false, code: 'ERR_ASSERTION', actual: false, expected: true, operator: '==' }
Assertions2.js
#!/usr/bin/env node;
const Utils = require('./Utils');
const assert = require('assert');

const TEST_BASE = 0.9;

function exponentiation(base, powerArg) {
	assert(powerArg >= 0, "exponentiation() power must be non-negative, was " + powerArg);
	let power = powerArg;
	let result = 1;
	while (power > 0) {
		result *= base;
		--power;
	}
	return result;
}

const main = async () => {
	for (let p = 10; p >= -1; --p) {
		console.log(Utils.format("{0:f} ^ {1:d} = {2:f}", TEST_BASE, p, exponentiation(TEST_BASE, p)));
	}
}
main().catch( e => { console.error(e) } );
Output
$ node Assertions2.js 0.9 ^ 10 = 0.34867844010000015 0.9 ^ 9 = 0.38742048900000015 0.9 ^ 8 = 0.43046721000000016 0.9 ^ 7 = 0.47829690000000014 0.9 ^ 6 = 0.5314410000000002 0.9 ^ 5 = 0.5904900000000002 0.9 ^ 4 = 0.6561000000000001 0.9 ^ 3 = 0.7290000000000001 0.9 ^ 2 = 0.81 0.9 ^ 1 = 0.9 0.9 ^ 0 = 1 AssertionError [ERR_ASSERTION]: exponentiation() power must be non-negative, was -1 at exponentiation (/Users/rich/Desktop/Resources/pureprogrammer/js/examples/Assertions2.js:8:2) at main (/Users/rich/Desktop/Resources/pureprogrammer/js/examples/Assertions2.js:20:67) at Object.<anonymous> (/Users/rich/Desktop/Resources/pureprogrammer/js/examples/Assertions2.js:23:1) at Module._compile (node:internal/modules/cjs/loader:1256:14) at Module._extensions..js (node:internal/modules/cjs/loader:1310:10) at Module.load (node:internal/modules/cjs/loader:1119:32) at Module._load (node:internal/modules/cjs/loader:960:12) at Function.executeUserEntryPoint [as runMain] (node:internal/modules/run_main:81:12) at node:internal/main/run_main_module:23:47 { generatedMessage: false, code: 'ERR_ASSERTION', actual: false, expected: true, operator: '==' }
Assertions3.js
#!/usr/bin/env node;
const Utils = require('./Utils');
const assert = require('assert');

const TEST_BASE = 0.9;

function exponentiation(base, powerArg) {
	assert(powerArg >= 0, "exponentiation() power must be non-negative, was " + powerArg);
	let power = powerArg;
	let result = 1;
	while (power > 0) {
		result *= base;
		--power;
	}
// This line will make the result incorrect.
	result = -result;
// If power is odd and base is negative, then result should be negative.
// Otherwise result should be positive.
	assert((power & 1) === 1 && (base < 0) ? result < 0 : result >= 0, "Postcondition Failed: Result is wrong sign");
	return result;
}

const main = async () => {
	for (let p = 10; p >= -1; --p) {
		console.log(Utils.format("{0:f} ^ {1:d} = {2:f}", TEST_BASE, p, exponentiation(TEST_BASE, p)));
	}
}
main().catch( e => { console.error(e) } );
Output
$ node Assertions3.js AssertionError [ERR_ASSERTION]: Postcondition Failed: Result is wrong sign at exponentiation (/Users/rich/Desktop/Resources/pureprogrammer/js/examples/Assertions3.js:19:2) at main (/Users/rich/Desktop/Resources/pureprogrammer/js/examples/Assertions3.js:25:67) at Object.<anonymous> (/Users/rich/Desktop/Resources/pureprogrammer/js/examples/Assertions3.js:28:1) at Module._compile (node:internal/modules/cjs/loader:1256:14) at Module._extensions..js (node:internal/modules/cjs/loader:1310:10) at Module.load (node:internal/modules/cjs/loader:1119:32) at Module._load (node:internal/modules/cjs/loader:960:12) at Function.executeUserEntryPoint [as runMain] (node:internal/modules/run_main:81:12) at node:internal/main/run_main_module:23:47 { generatedMessage: false, code: 'ERR_ASSERTION', actual: false, expected: true, operator: '==' }
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