feat[2020-day-02]: utilities for formatting and validating passwords

criteria per instructions in part 1

Author: developher-net

2020/day-02/cleanupPasswords.js

@@ -0,0 +1,47 @@
+/**
+ * Splits a password record into its component parts
+ */
+const splitRecord = (row) => {
+  const record = row.split(': ')
+    .map((el) => el.trim())
+
+  return {
+    rule: record[0],
+    password: record[1]
+  }
+}
+
+/**
+ * Splits a password validation rule into its component parts
+ */
+const splitRule = (rule) => {
+  const splitRow = rule.split(/-| /)
+
+  return {
+    min: Number(splitRow[0]),
+    max: Number(splitRow[1]),
+    char: String(splitRow[2])
+  }
+}
+
+/**
+ * Validates a password against the specified rule
+ */
+const isValid = (rule, password) => {
+  // count how many times `rule.char` exists in `password`
+  const count = (
+    password.match(
+      new RegExp(rule.char, 'g')
+    ) || []
+  ).length
+  // check the conditions
+  if (count < rule.min) return false
+  if (count > rule.max) return false
+  return true
+}
+
+module.exports = {
+  splitRecord,
+  splitRule,
+  isValid
+}

2020/day-02/cleanupPasswords.test.js

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+/* eslint-env mocha */
+const { expect } = require('chai')
+const { splitRecord, splitRule, isValid } = require('./cleanupPasswords')
+
+const testData = [
+  '1-3 a: abcde',
+  '1-3 b: cdefg',
+  '2-9 c: ccccccccc'
+]
+
+describe('--- Day 2: Password Philosophy ---', () => {
+  describe('Part 1', () => {
+    describe('splitRecord()', () => {
+      it('splits a password record into components parts', () => {
+        testData.forEach((row, idx) => {
+          const { rule, password } = splitRecord(row)
+          expect(`${rule}: ${password}`).to.equal(testData[idx])
+        })
+      })
+    })
+    describe('splitRule()', () => {
+      it('splits a password formatting rule into component parts', () => {
+        testData.forEach((row, idx) => {
+          const { rule, password } = splitRecord(row)
+          const { min, max, char } = splitRule(rule)
+          expect(`${min}-${max} ${char}: ${password}`).to.equal(testData[idx])
+        })
+      })
+    })
+    describe('isValid()', () => {
+      it('checks if a specified password matches the specified rule', () => {
+        const expectedResults = [true, false, true]
+        testData.forEach((row, idx) => {
+          const { rule, password } = splitRecord(row)
+          const { min, max, char } = splitRule(rule)
+          expect(isValid({ min, max, char }, password))
+            .to.equal(expectedResults[idx])
+        })
+      })
+    })
+  })
+})