Add a simple test case.

internal/ngram/ngram_test.go

@@ -0,0 +1,19 @@
+package ngram_test
+
+import (
+	"testing"
+
+	"github.com/gslin/go-ir-playground/internal/ngram"
+)
+
+func TestUnigram(t *testing.T) {
+	a := ngram.Unigram("test")
+	if len(a) != 1 || a[0] != "test" {
+		t.Error()
+	}
+
+	a = ngram.Unigram("測試")
+	if len(a) != 2 || a[0] != "測" || a[1] != "試" {
+		t.Error()
+	}
+}