Implement Azure Files backend

Co-authored-by: moongdal <moongdal@tutanota.com>

backend/azurefiles/azurefiles_internal_test.go

@@ -0,0 +1,67 @@
+package azurefiles
+
+import (
+	"context"
+	"math/rand"
+	"strings"
+	"testing"
+
+	"github.com/rclone/rclone/fstest/fstests"
+	"github.com/stretchr/testify/assert"
+)
+
+func (f *Fs) InternalTest(t *testing.T) {
+	t.Run("Authentication", f.InternalTestAuth)
+}
+
+var _ fstests.InternalTester = (*Fs)(nil)
+
+func (f *Fs) InternalTestAuth(t *testing.T) {
+	t.Skip("skipping since this requires authentication credentials which are not part of repo")
+	shareName := "test-rclone-oct-2023"
+	testCases := []struct {
+		name    string
+		options *Options
+	}{
+		{
+			name: "ConnectionString",
+			options: &Options{
+				ShareName:        shareName,
+				ConnectionString: "",
+			},
+		},
+		{
+			name: "AccountAndKey",
+			options: &Options{
+				ShareName: shareName,
+				Account:   "",
+				Key:       "",
+			}},
+		{
+			name: "SASUrl",
+			options: &Options{
+				ShareName: shareName,
+				SASUrl:    "",
+			}},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			fs, err := newFsFromOptions(context.TODO(), "TestAzureFiles", "", tc.options)
+			assert.NoError(t, err)
+			dirName := randomString(10)
+			assert.NoError(t, fs.Mkdir(context.TODO(), dirName))
+		})
+	}
+}
+
+const chars = "abcdefghijklmnopqrstuvwzyxABCDEFGHIJKLMNOPQRSTUVWZYX"
+
+func randomString(charCount int) string {
+	strBldr := strings.Builder{}
+	for i := 0; i < charCount; i++ {
+		randPos := rand.Int63n(52)
+		strBldr.WriteByte(chars[randPos])
+	}
+	return strBldr.String()
+}