feat: add hw4

Author: TaiYou-TW

hw4/.gitignore

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+reports/
+.stryker-tmp/

hw4/README.md

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+# HW4
+
+You can install package through:
+
+```shell
+npm i
+```
+
+After finish your test code in `tests/calculator_test.js`, you can run `Stryker` by:
+
+```shell
+npm run mutate
+```
+
+to get your mutation testing result.

hw4/package-lock.json

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+{
+    "name": "hw4",
+    "version": "1.0.0",
+    "description": "software testing hw4",
+    "main": "src/calculator.js",
+    "scripts": {
+        "test": "node --test",
+        "mutate": "npx stryker run"
+    },
+    "dependencies": {},
+    "devDependencies": {
+        "@stryker-mutator/core": "^8.2.6"
+    },
+    "license": "MIT"
+}

hw4/package.json

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+class Calculator {
+    static main(month1, day1, month2, day2, year) {
+        if (month1 < 1 || month1 > 12) {
+            throw new Error("invalid month1");
+        }
+        if (month2 < 1 || month2 > 12) {
+            throw new Error("invalid month2");
+        }
+        if (day1 < 1 || day1 > 31) {
+            throw new Error("invalid day1");
+        }
+        if (day2 < 1 || day2 > 31) {
+            throw new Error("invalid day2");
+        }
+        if (year < 1 || year > 10000) {
+            throw new Error("invalid year");
+        }
+        if (month1 === month2 && day1 > day2) {
+            throw new Error("day1 must be less than day2 if month1 is equal to month2");
+        }
+        if (month1 > month2) {
+            throw new Error("month1 must be less than month2");
+        }
+
+        return this.#calculate(month1, day1, month2, day2, year);
+    }
+
+    static #calculate(month1, day1, month2, day2, year) {
+        let numDays;
+
+        if (month2 === month1) {
+            numDays = day2 - day1;
+        } else {
+            // ignore 0 index
+            let daysIn = [0, 31, 0, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31];
+            if (this.#isLeapYear(year))
+                daysIn[2] = 28;
+            else
+                daysIn[2] = 29;
+
+            numDays = day2 + (daysIn[month1] - day1);
+
+            for (let i = month1 + 1; i <= month2 - 1; i++)
+                numDays += daysIn[i];
+        }
+        return numDays;
+    }
+
+    static #isLeapYear(year) {
+        return ((year % 4 === 0) && (year % 100 !== 0)) || (year % 400 === 0);
+    }
+}
+
+module.exports = Calculator;

hw4/src/calculator.js

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+{
+  "$schema": "./node_modules/@stryker-mutator/core/schema/stryker-schema.json",
+  "_comment": "This config was generated using 'stryker init'. Please take a look at: https://stryker-mutator.io/docs/stryker-js/configuration/ for more information.",
+  "packageManager": "npm",
+  "reporters": [
+    "html",
+    "clear-text",
+    "progress"
+  ],
+  "testRunner": "command",
+  "testRunner_comment": "Take a look at (missing 'homepage' URL in package.json) for information about the command plugin.",
+  "coverageAnalysis": "off"
+}

hw4/stryker.config.json

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+const assert = require('assert');
+const { test } = require('node:test');
+
+const Calculator = require('../src/calculator');
+
+// TODO: write your test cases here to kill mutants