diff --git a/metainfo/piece-length_test.go b/metainfo/piece-length_test.go
new file mode 100644
index 00000000..b88ca8e3
--- /dev/null
+++ b/metainfo/piece-length_test.go
@@ -0,0 +1,31 @@
+package metainfo
+
+import "testing"
+
+func TestChoosePieceLength(t *testing.T) {
+	testCases := []struct {
+		name        string // test case name
+		totalLength int64
+		want        int64 // desired piece length
+	}{
+		{name: "1KB file", totalLength: 1024, want: minimumPieceLength},
+		{name: "minimumPieceLength KB file", totalLength: minimumPieceLength, want: minimumPieceLength},
+		{name: "minimumPieceLength KB + 1B file", totalLength: minimumPieceLength + 1, want: minimumPieceLength},
+
+		{name: "max piece number", totalLength: targetPieceCountMax * minimumPieceLength, want: minimumPieceLength},
+		{name: "over max piece number", totalLength: targetPieceCountMax*minimumPieceLength + 1, want: minimumPieceLength * 2},
+
+		{name: "larger file size", totalLength: 10 * 1024 * 1024 * 1024, want: maximumPieceLength},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			got := ChoosePieceLength(tc.totalLength)
+			if got != tc.want {
+				t.Errorf("got %d, want %d", got, tc.want)
+			} else {
+				t.Logf("got %d, piece number %d", got,tc.totalLength/got)
+			}
+		})
+	}
+}