Add test cases for 1-js/06-advanced-functions/03-closure/9-sort-by-field

Just a simple check to see if the code works on the example given in the task.

1-js/06-advanced-functions/03-closure/9-sort-by-field/_js.view/solution.js

@@ -0,0 +1,6 @@
+"use strict";
+
+function byField(fieldName){
+  return (a, b) => a[field] > b[field] ? 1 : -1;
+}
+

1-js/06-advanced-functions/03-closure/9-sort-by-field/_js.view/source.js

@@ -0,0 +1,7 @@
+"use strict";
+
+function byField(fieldName){
+  
+  //Your code goes here.
+
+}

1-js/06-advanced-functions/03-closure/9-sort-by-field/_js.view/test.js

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+"use strict";
+
+describe("byField", function(){
+  
+  let users = [
+    { name: "John", age: 20, surname: "Johnson" },
+    { name: "Pete", age: 18, surname: "Peterson" },
+    { name: "Ann", age: 19, surname: "Hathaway" },
+  ];
+
+  it("sorts users by name", function(){
+    let nameSortedKey = [
+      { name: "Ann", age: 19, surname: "Hathaway" },
+      { name: "John", age: 20, surname: "Johnson"},    
+      { name: "Pete", age: 18, surname: "Peterson" },
+    ];
+    let nameSortedAnswer = users.sort(byField("name"));
+    assert.equal(JSON.stringify(nameSortedKey), JSON.stringify(nameSortedAnswer));
+  });
+
+  it("sorts users by age", function(){
+    let ageSortedKey = [
+      { name: "Pete", age: 18, surname: "Peterson" },
+      { name: "Ann", age: 19, surname: "Hathaway" },
+      { name: "John", age: 20, surname: "Johnson"}, 
+    ];
+    let ageSortedAnswer = users.sort(byField("age"));
+    assert.equal(JSON.stringify(ageSortedKey), JSON.stringify(ageSortedKey));
+  });
+
+  it("sorts users by surname", function(){
+    let surnameSortedKey = [
+      { name: "Ann", age: 19, surname: "Hathaway" },
+      { name: "John", age: 20, surname: "Johnson"},
+      { name: "Pete", age: 18, surname: "Peterson" },
+    ];
+    let surnameSortedAnswer = users.sort(byField("surname"));
+    assert.equal(JSON.stringify(surnameSortedAnswer), JSON.stringify(surnameSortedKey));
+  });
+
+});