Sort keys in createSearch + add tests

server/utils/__tests__/createSearch-test.js

@@ -0,0 +1,15 @@
+const createSearch = require("../createSearch");
+
+describe("createSearch", () => {
+  it("omits the trailing = for empty string values", () => {
+    expect(createSearch({ a: "a", b: "" })).toEqual("?a=a&b");
+  });
+
+  it("sorts keys", () => {
+    expect(createSearch({ b: "b", a: "a", c: "c" })).toEqual("?a=a&b=b&c=c");
+  });
+
+  it("returns an empty string when there are no params", () => {
+    expect(createSearch({})).toEqual("");
+  });
+});

server/utils/createSearch.js

@@ -1,17 +1,16 @@
 function createSearch(query) {
-  const params = [];
+  const keys = Object.keys(query).sort();
+  const params = keys.reduce(
+    (memo, key) =>
+      memo.concat(
+        query[key] === ""
+          ? key // Omit the trailing "=" from key=
+          : `${key}=${encodeURIComponent(query[key])}`
+      ),
+    []
+  );
 
-  Object.keys(query).forEach(param => {
-    if (query[param] === "") {
-      params.push(param); // Omit the trailing "=" from param=
-    } else {
-      params.push(`${param}=${encodeURIComponent(query[param])}`);
-    }
-  });
-
-  const search = params.join("&");
-
-  return search ? `?${search}` : "";
+  return params.length ? `?${params.join("&")}` : "";
 }
 
 module.exports = createSearch;