Implement lookup function and tests

Author: Richiealx

Sprint-2/implement/lookup.js

@@ -1,5 +1,37 @@
-function createLookup() {
-  // implementation here
+/**
+ * createLookup()
+ *
+ * Converts an array of [key, value] pairs into a lookup object.
+ *
+ * Example:
+ * [['US', 'USD'], ['CA', 'CAD']]
+ *
+ * Returns:
+ * { US: 'USD', CA: 'CAD' }
+ */
+
+function createLookup(pairs) {
+  // Ensure the input is an array
+  if (!Array.isArray(pairs)) {
+    throw new Error("Expected an array of pairs");
+  }
+
+  const lookup = {};
+
+  // Loop through each pair
+  for (const pair of pairs) {
+    // Validate that each pair has exactly two values
+    if (!Array.isArray(pair) || pair.length !== 2) {
+      throw new Error("Each item must be a [key, value] pair");
+    }
+
+    const [key, value] = pair;
+
+    // Add to lookup object
+    lookup[key] = value;
+  }
+
+  return lookup;
 }
 
 module.exports = createLookup;

Sprint-2/implement/lookup.test.js

@@ -1,35 +1,34 @@
 const createLookup = require("./lookup.js");
 
-test.todo("creates a country currency code lookup for multiple codes");
-
-/*
-
-Create a lookup object of key value pairs from an array of code pairs
-
-Acceptance Criteria:
-
-Given
- - An array of arrays representing country code and currency code pairs
-   e.g. [['US', 'USD'], ['CA', 'CAD']]
-
-When
- - createLookup function is called with the country-currency array as an argument
-
-Then
- - It should return an object where:
- - The keys are the country codes
- - The values are the corresponding currency codes
-
-Example
-Given: [['US', 'USD'], ['CA', 'CAD']]
-
-When
-createLookup(countryCurrencyPairs) is called
-
-Then
-It should return:
- {
-   'US': 'USD',
-   'CA': 'CAD'
- }
-*/
+describe("createLookup()", () => {
+  test("creates a country currency code lookup for multiple codes", () => {
+    const pairs = [
+      ["US", "USD"],
+      ["CA", "CAD"],
+    ];
+
+    expect(createLookup(pairs)).toEqual({
+      US: "USD",
+      CA: "CAD",
+    });
+  });
+
+  test("returns an empty object for an empty array", () => {
+    expect(createLookup([])).toEqual({});
+  });
+
+  test("overwrites duplicate keys with the last value", () => {
+    const pairs = [
+      ["US", "USD"],
+      ["US", "USN"],
+    ];
+
+    expect(createLookup(pairs)).toEqual({
+      US: "USN",
+    });
+  });
+
+  test("throws an error when input is not an array", () => {
+    expect(() => createLookup("invalid")).toThrow();
+  });
+});