Done with the book! Added hash maps and the puts builtin.

Signed-off-by: jmug <u.g.a.mariano@gmail.com>

pkg/object/object_test.go

@@ -0,0 +1,22 @@
+package object
+
+import "testing"
+
+func TestStringHashKey(t *testing.T) {
+	hello1 := &String{Value: "Hello World"}
+	hello2 := &String{Value: "Hello World"}
+	diff1 := &String{Value: "My name is johnny"}
+	diff2 := &String{Value: "My name is johnny"}
+
+	if hello1.HashKey() != hello2.HashKey() {
+		t.Errorf("strings with same content have different hash keys")
+	}
+
+	if diff1.HashKey() != diff2.HashKey() {
+		t.Errorf("strings with same content have different hash keys")
+	}
+
+	if hello1.HashKey() == diff1.HashKey() {
+		t.Errorf("strings with different content have same hash keys")
+	}
+}