Add Lab content

.circleci/config.yaml

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+version: 2.1
+orbs:
+  node: circleci/node@3.0.0
+workflows:
+  node-tests:
+    jobs:
+      - node/test

__tests__/index.test.js

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+const calculator = require("../");
+const resetArgV = () => {
+  process.argv = ["/path/to/node", "/path/to/file"];
+};
+
+describe("calculator()", () => {
+  describe("error handling", () => {
+    beforeEach(resetArgV);
+    test("should return an error message if no operation is provided", () => {
+      const actual = calculator();
+      const expected = "No operation provided...";
+      expect(actual).toEqual(expected);
+    });
+
+    test("should return an error message if no numbers are provided", () => {
+      const command = "plus";
+      process.argv.push(command);
+
+      const actual = calculator();
+      const expected = "No numbers provided...";
+      expect(actual).toEqual(expected);
+    });
+
+    test("should return an error message if the operation does not match 'plus' or 'minus'", () => {
+      const command = "modulo";
+      const numbers = ["5", "10"];
+      process.argv.push(command, ...numbers);
+
+      const actual = calculator();
+      const expected = "Invalid operation: modulo";
+      expect(actual).toEqual(expected);
+    });
+  });
+
+  describe("plus", () => {
+    beforeEach(resetArgV);
+    test("should add up two numbers", () => {
+      const command = "plus";
+      const numbers = ["5", "10"];
+      process.argv.push(command, ...numbers);
+
+      const actual = calculator();
+      const expected = 15;
+      expect(actual).toEqual(expected);
+    });
+
+    test("should add up multiple numbers", () => {
+      const command = "plus";
+      const numbers = ["5", "10", "15", "30", "60"];
+      process.argv.push(command, ...numbers);
+
+      const actual = calculator();
+      const expected = 120;
+      expect(actual).toEqual(expected);
+    });
+
+    test("should add negative numbers", () => {
+      const command = "plus";
+      const numbers = ["5", "-10", "15", "30", "-60"];
+      process.argv.push(command, ...numbers);
+
+      const actual = calculator();
+      const expected = -20;
+      expect(actual).toEqual(expected);
+    });
+
+    test("should return the first number if there is only one number", () => {
+      const command = "plus";
+      const numbers = ["5"];
+      process.argv.push(command, ...numbers);
+
+      const actual = calculator();
+      const expected = 5;
+      expect(actual).toEqual(expected);
+    });
+  });
+
+  describe("minus", () => {
+    beforeEach(resetArgV);
+    test("should subtract two numbers", () => {
+      const command = "minus";
+      const numbers = ["15", "10"];
+      process.argv.push(command, ...numbers);
+
+      const actual = calculator();
+      const expected = 5;
+      expect(actual).toEqual(expected);
+    });
+
+    test("should subtract multiple numbers", () => {
+      const command = "minus";
+      const numbers = ["60", "10", "15", "30", "5"];
+      process.argv.push(command, ...numbers);
+
+      const actual = calculator();
+      const expected = 0;
+      expect(actual).toEqual(expected);
+    });
+
+    test("should subtract negative numbers", () => {
+      const command = "minus";
+      const numbers = ["5", "-10", "15", "30", "-60"];
+      process.argv.push(command, ...numbers);
+
+      const actual = calculator();
+      const expected = 30;
+      expect(actual).toEqual(expected);
+    });
+
+    test("should return the first number if there is only one number", () => {
+      const command = "minus";
+      const numbers = ["5"];
+      process.argv.push(command, ...numbers);
+
+      const actual = calculator();
+      const expected = 5;
+      expect(actual).toEqual(expected);
+    });
+  });
+});

index.js

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+/**
+ * The function below has no parameters. Instead, access the arguments from the command line.
+ * The first argument passed after the filename should be either "plus" or "minus", which represents the kind of calculation that will be done. Every argument afterwards should be a number.
+ * Depending on the operation, either add up all of the numbers or subtract all of the numbers, from left to right.
+ * @returns {number} The result of either adding all numbers or subtracting all numbers, depending on the arguments added to the command line.
+ */
+function calculator() {}
+
+// Don't change anything below this line.
+module.exports = calculator;