Fix querystring parser and add edge case tests

Author: Richiealx

Sprint-2/implement/querystring.js

@@ -1,12 +1,43 @@
+/**
+ * parseQueryString()
+ *
+ * Parses a query string into an object of key-value pairs.
+ *
+ * Example:
+ * parseQueryString("name=Richard&city=Sheffield")
+ * returns { name: "Richard", city: "Sheffield" }
+ */
+
 function parseQueryString(queryString) {
   const queryParams = {};
-  if (queryString.length === 0) {
+
+  // Return an empty object if the input is an empty string
+  if (typeof queryString !== "string" || queryString.length === 0) {
     return queryParams;
   }
+
+  // Split the full query string into key-value pairs
   const keyValuePairs = queryString.split("&");
 
   for (const pair of keyValuePairs) {
-    const [key, value] = pair.split("=");
+    // Skip empty pairs, for example from a trailing "&"
+    if (pair === "") {
+      continue;
+    }
+
+    // Find the position of the first "="
+    const separatorIndex = pair.indexOf("=");
+
+    // If there is no "=" sign, treat it as a key with an empty value
+    if (separatorIndex === -1) {
+      queryParams[pair] = "";
+      continue;
+    }
+
+    // Extract the key and everything after the first "=" as the value
+    const key = pair.slice(0, separatorIndex);
+    const value = pair.slice(separatorIndex + 1);
+
     queryParams[key] = value;
   }
 

Sprint-2/implement/querystring.test.js

@@ -1,12 +1,44 @@
-// In the prep, we implemented a function to parse query strings.
-// Unfortunately, it contains several bugs!
-// Below is one test case for an edge case the implementation doesn't handle well.
-// Fix the implementation for this test, and try to think of as many other edge cases as possible - write tests and fix those too.
+const parseQueryString = require("./querystring.js");
 
-const parseQueryString = require("./querystring.js")
+describe("parseQueryString()", () => {
+  test("parses querystring values containing =", () => {
+    expect(parseQueryString("equation=x=y+1")).toEqual({
+      equation: "x=y+1",
+    });
+  });
+
+  test("returns an empty object for an empty string", () => {
+    expect(parseQueryString("")).toEqual({});
+  });
+
+  test("parses a single key-value pair", () => {
+    expect(parseQueryString("name=Richard")).toEqual({
+      name: "Richard",
+    });
+  });
+
+  test("parses multiple key-value pairs", () => {
+    expect(parseQueryString("name=Richard&city=Sheffield")).toEqual({
+      name: "Richard",
+      city: "Sheffield",
+    });
+  });
+
+  test("handles a key with an empty value", () => {
+    expect(parseQueryString("name=")).toEqual({
+      name: "",
+    });
+  });
+
+  test("handles a key with no equals sign", () => {
+    expect(parseQueryString("name")).toEqual({
+      name: "",
+    });
+  });
 
-test("parses querystring values containing =", () => {
-  expect(parseQueryString("equation=x=y+1")).toEqual({
-    "equation": "x=y+1",
+  test("ignores an empty trailing pair", () => {
+    expect(parseQueryString("name=Richard&")).toEqual({
+      name: "Richard",
+    });
   });
 });