api: Add go files

I know this is a huge commit, but I can't be bothered to check
this in part by part.

api/commenter_session_get_test.go

@@ -0,0 +1,46 @@
+package main
+
+import (
+	"testing"
+)
+
+func TestCommenterSessionGetBasics(t *testing.T) {
+	failTestOnError(t, setupTestEnv())
+
+	commenterHex, _ := commenterNew("test@example.com", "Test", "undefined", "https://example.com/photo.jpg", "google")
+
+	session, _ := commenterSessionNew()
+
+	commenterSessionUpdate(session, commenterHex)
+
+	cs, err := commenterSessionGet(session)
+	if err != nil {
+		t.Errorf("unexpected error found when getting session information: %v", err)
+		return
+	}
+
+	if cs.CommenterHex != commenterHex {
+		t.Errorf("expected commenterHex=%s got commenterHex=%s", commenterHex, cs.CommenterHex)
+		return
+	}
+}
+
+func TestCommenterSessionGetDNE(t *testing.T) {
+	failTestOnError(t, setupTestEnv())
+
+	_, err := commenterSessionGet("does-not-exist")
+	if err == nil {
+		t.Errorf("expected error not found when invalid session")
+		return
+	}
+}
+
+func TestCommenterSessionGetEmpty(t *testing.T) {
+	failTestOnError(t, setupTestEnv())
+
+	_, err := commenterSessionGet("")
+	if err == nil {
+		t.Errorf("expected error not found with empty session")
+		return
+	}
+}