Use testify.

go.mod

@@ -1,3 +1,10 @@
 module github.com/gslin/go-ir-playground
 
 go 1.21.6
+
+require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/stretchr/testify v1.8.4 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+)

internal/ngram/ngram_test.go

@@ -2,18 +2,18 @@ package ngram_test
 
 import (
 	"testing"
+	"github.com/stretchr/testify/assert"
 
 	"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()
-	}
+	assert.Equal(t, len(a), 1)
+	assert.Equal(t, a[0], "test")
 
 	a = ngram.Unigram("測試")
-	if len(a) != 2 || a[0] != "測" || a[1] != "試" {
-		t.Error()
-	}
+	assert.Equal(t, len(a), 2)
+	assert.Equal(t, a[0], "測")
+	assert.Equal(t, a[1], "試")
 }