diff --git a/diff/diff_test.go b/diff/diff_test.go
new file mode 100644
index 0000000..27f2910
--- /dev/null
+++ b/diff/diff_test.go
@@ -0,0 +1,60 @@
+package diff_test
+
+import (
+	"fmt"
+	"reflect"
+	"testing"
+
+	"code.ivysaur.me/yatwiki3/diff"
+)
+
+func TestDiff(t *testing.T) {
+
+	type testCase struct {
+		o, n   []string
+		expect []diff.Instruction
+	}
+
+	testCases := []testCase{
+		{
+			[]string{},
+			[]string{},
+			[]diff.Instruction{},
+		},
+		{
+			[]string{"a"},
+			[]string{"b"},
+			[]diff.Instruction{
+				{diff.OP_REMOVED, []string{"a"}},
+				{diff.OP_INSERTED, []string{"b"}},
+			},
+		},
+		{
+			[]string{"a", "b", "c"},
+			[]string{"a", "b", "c", "d"},
+			[]diff.Instruction{
+				{diff.OP_UNCHANGED, []string{"a", "b", "c"}},
+				{diff.OP_INSERTED, []string{"d"}},
+			},
+		},
+		{
+			[]string{"a", "b", "c", "d"},
+			[]string{"a", "b", "X", "Y", "Z", "d"},
+			[]diff.Instruction{
+				{diff.OP_UNCHANGED, []string{"a", "b"}},
+				{diff.OP_REMOVED, []string{"c"}},
+				{diff.OP_INSERTED, []string{"X", "Y", "Z"}},
+				{diff.OP_UNCHANGED, []string{"d"}},
+			},
+		},
+	}
+
+	for _, testCase := range testCases {
+		output := diff.Diff(testCase.o, testCase.n)
+		if !reflect.DeepEqual(output, testCase.expect) {
+			t.Fail()
+			fmt.Printf("==EXPECTED==\n%#v\n==GOT==\n%#v\n", testCase.expect, output)
+		}
+	}
+
+}