2 files changed, 80 insertions, 0 deletions
diff --git a/db/db.go b/db/db.go
index 6dfda22..bbe5b36 100644
--- a/db/db.go
+++ b/db/db.go
@@ -82,3 +82,17 @@ func (fdb *FernDB) Exists(feed, entry string) bool {
 
 }
 
+func (fdb *FernDB) Add(feed, entry string) {
+	// Check if entry already exist for feed.
+	if fdb.Exists(feed, entry) {
+		return
+	}
+
+	// Add entry.
+	fdb.mutex.Lock()
+	if _, ok := fdb.downloaded[feed]; !ok {
+		fdb.downloaded[feed] = make([]string, 0)
+	}
+	fdb.downloaded[feed] = append(fdb.downloaded[feed], entry)
+	fdb.mutex.Unlock()
+}
diff --git a/db/db_test.go b/db/db_test.go
index 9a8642a..8fc9fed 100644
--- a/db/db_test.go
+++ b/db/db_test.go
@@ -182,3 +182,69 @@ func TestExists(t *testing.T) {
 		return
 	}
 }
+
+func TestAdd(t *testing.T) {
+	// Set custom path for db.
+	dbPath = path.Join(os.TempDir(), "fern-db.json")
+	defer os.Remove(dbPath)
+
+	// Write a sample test db to fern-db.json
+	testDBJSON := []byte(`{"npr":["william-prince","joy-oladokun"]}`)
+	dbFile, err := os.Create(dbPath)
+	defer dbFile.Close()
+	if err != nil {
+		t.Errorf("Unable to create fern-db.json: %v", err.Error())
+		return
+	}
+	n, err := dbFile.Write(testDBJSON)
+	if len(testDBJSON) != n {
+		t.Errorf("Write to fern-db.json failed: %v", err.Error())
+		return
+	}
+
+	// Open the db.
+	db, err := Open()
+	if err != nil {
+		t.Errorf("db.Open failed: %v", err.Error())
+		return
+	}
+
+	// Test `Add` for an existing feed.
+	db.Add("npr", "julian-baker")
+	if len(db.downloaded["npr"]) != 3 {
+		t.Errorf("db.Add failed: expected 3 entries for 'npr'")
+		return
+	}
+	if !db.Exists("npr", "julian-baker") {
+		t.Errorf("db.Add failed: expected %s in 'npr' feed",
+			"julian-baker")
+		return
+	}
+	db.Add("npr", "julian-baker")
+	if len(db.downloaded["npr"]) != 3 {
+		t.Errorf("db.Add failed: expected 3 entries for 'npr'")
+		return
+	}
+
+	// Test `Add` for nonexistent feed.
+	db.Add("mark-rober", "glitter-bomb")
+	if len(db.downloaded["mark-rober"]) != 1 {
+		t.Errorf("db.Add failed: expected 1 entry for 'mark-rober'")
+		return
+	}
+	if !db.Exists("mark-rober", "glitter-bomb") {
+		t.Errorf("db.Add failed: expected %s in 'mark-rober' feed",
+			"glitter-bomb")
+		return
+	}
+	db.Add("mark-rober", "squirrel-maze")
+	if len(db.downloaded["mark-rober"]) != 2 {
+		t.Errorf("db.Add failed: expected 2 entries for 'mark-rober'")
+		return
+	}
+	if !db.Exists("mark-rober", "squirrel-maze") {
+		t.Errorf("db.Add failed: expected %s in 'mark-rober' feed",
+			"squirrel-maze")
+		return
+	}
+}