unit test cases for /pkg/util/misc (#755)

* unit test cases for /pkg/util/misc

* Add License discription

* Fix the import format

* add dependency

go.mod

@@ -66,6 +66,7 @@ require (
 	github.com/docker/distribution v2.7.1+incompatible // indirect
 	github.com/docker/docker v20.10.11+incompatible // indirect
 	github.com/docker/go-connections v0.4.0 // indirect
+	github.com/dubbogo/tools v1.0.9 // indirect
 	github.com/dustin/go-humanize v1.0.0 // indirect
 	github.com/gin-contrib/sse v0.1.0 // indirect
 	github.com/go-errors/errors v1.0.1 // indirect

pkg/util/misc/misc_test.go

@@ -0,0 +1,99 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package misc_test
+
+import (
+	"bytes"
+	"errors"
+	"testing"
+)
+
+import (
+	"github.com/arana-db/arana/pkg/util/misc"
+)
+
+func TestParseTable(t *testing.T) {
+	tests := []struct {
+		input string
+		db    string
+		tbl   string
+		err   error
+	}{
+		{"dbname.tablename", "dbname", "tablename", nil},
+		{"invalid", "", "", errors.New("invalid table name: invalid")},
+		{"", "", "", errors.New("invalid table name: ")},
+	}
+
+	for _, tt := range tests {
+		db, tbl, err := misc.ParseTable(tt.input)
+		if db != tt.db || tbl != tt.tbl || (err != nil && err.Error() != tt.err.Error()) {
+			t.Errorf("ParseTable(%s) = (%s, %s, %v), want (%s, %s, %v)", tt.input, db, tbl, err, tt.db, tt.tbl, tt.err)
+		}
+	}
+}
+
+func TestTryClose(t *testing.T) {
+	var buf bytes.Buffer
+	err := misc.TryClose(&buf)
+	if err != nil {
+		t.Errorf("TryClose() failed on a valid io.Closer: %v", err)
+	}
+
+	err = misc.TryClose(123) // an integer isn't an io.Closer
+	if err != nil {
+		t.Errorf("TryClose() failed on an invalid io.Closer: %v", err)
+	}
+}
+
+func TestReverseSlice(t *testing.T) {
+	tests := []struct {
+		input    []int
+		expected []int
+	}{
+		{[]int{1, 2, 3}, []int{3, 2, 1}},
+		{[]int{}, []int{}},
+		{[]int{1}, []int{1}},
+	}
+
+	for _, tt := range tests {
+		misc.ReverseSlice(tt.input)
+		for i, val := range tt.input {
+			if val != tt.expected[i] {
+				t.Errorf("ReverseSlice(%v) = %v, want %v", tt.input, tt.input, tt.expected)
+				break
+			}
+		}
+	}
+}
+
+func TestCartesianProduct(t *testing.T) {
+	input := [][]int{{1, 2}, {3, 4}}
+	expected := [][]int{{1, 3}, {1, 4}, {2, 3}, {2, 4}}
+	result := misc.CartesianProduct(input)
+	if len(result) != len(expected) {
+		t.Fatalf("CartesianProduct(%v) has %d results, want %d", input, len(result), len(expected))
+	}
+	for i, slice := range result {
+		for j, val := range slice {
+			if val != expected[i][j] {
+				t.Errorf("CartesianProduct(%v) = %v, want %v", input, result, expected)
+				break
+			}
+		}
+	}
+}