/*
 * Minio Cloud Storage, (C) 2016 Minio, Inc.
 *
 * Licensed 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 cmd

import (
	"bytes"
	"errors"
	"io"
	"io/ioutil"
	"os"
	slashpath "path"
	"runtime"
	"strings"
	"syscall"
	"testing"
)

// creates a temp dir and sets up posix layer.
// returns posix layer, temp dir path to be used for the purpose of tests.
func newPosixTestSetup() (StorageAPI, string, error) {
	diskPath, err := ioutil.TempDir(os.TempDir(), "minio-")
	if err != nil {
		return nil, "", err
	}
	posixStorage, err := newPosix(diskPath)
	if err != nil {
		return nil, "", err
	}
	return posixStorage, diskPath, nil
}

// Tests posix.getDiskInfo()
func TestGetDiskInfo(t *testing.T) {
	path, err := ioutil.TempDir(os.TempDir(), "minio-")
	if err != nil {
		t.Fatalf("Unable to create a temporary directory, %s", err)
	}
	defer removeAll(path)

	testCases := []struct {
		diskPath    string
		expectedErr error
	}{
		{path, nil},
		{"/nonexistent-dir", errDiskNotFound},
	}

	// Check test cases.
	for _, testCase := range testCases {
		if _, err := getDiskInfo(testCase.diskPath); err != testCase.expectedErr {
			t.Fatalf("expected: %s, got: %s", testCase.expectedErr, err)
		}
	}
}

// TestReadAll - Tests the functionality implemented by posix ReadAll storage API.
func TestReadAll(t *testing.T) {
	// create posix test setup
	posixStorage, path, err := newPosixTestSetup()
	if err != nil {
		t.Fatalf("Unable to create posix test setup, %s", err)
	}

	defer removeAll(path)

	// Create files for the test cases.
	if err = posixStorage.MakeVol("exists"); err != nil {
		t.Fatalf("Unable to create a volume \"exists\", %s", err)
	}
	if err = posixStorage.AppendFile("exists", "as-directory/as-file", []byte("Hello, World")); err != nil {
		t.Fatalf("Unable to create a file \"as-directory/as-file\", %s", err)
	}
	if err = posixStorage.AppendFile("exists", "as-file", []byte("Hello, World")); err != nil {
		t.Fatalf("Unable to create a file \"as-file\", %s", err)
	}
	if err = posixStorage.AppendFile("exists", "as-file-parent", []byte("Hello, World")); err != nil {
		t.Fatalf("Unable to create a file \"as-file-parent\", %s", err)
	}

	// Testcases to validate different conditions for ReadAll API.
	testCases := []struct {
		volume string
		path   string
		err    error
	}{
		// Test case - 1.
		// Validate volume does not exist.
		{
			volume: "i-dont-exist",
			path:   "",
			err:    errVolumeNotFound,
		},
		// Test case - 2.
		// Validate bad condition file does not exist.
		{
			volume: "exists",
			path:   "as-file-not-found",
			err:    errFileNotFound,
		},
		// Test case - 3.
		// Validate bad condition file exists as prefix/directory and
		// we are attempting to read it.
		{
			volume: "exists",
			path:   "as-directory",
			err:    errFileNotFound,
		},
		// Test case - 4.
		{
			volume: "exists",
			path:   "as-file-parent/as-file",
			err:    errFileNotFound,
		},
		// Test case - 5.
		// Validate the good condition file exists and we are able to read it.
		{
			volume: "exists",
			path:   "as-file",
			err:    nil,
		},
		// Test case - 6.
		// Test case with invalid volume name.
		{
			volume: "ab",
			path:   "as-file",
			err:    errInvalidArgument,
		},
	}

	var dataRead []byte
	// Run through all the test cases and validate for ReadAll.
	for i, testCase := range testCases {
		dataRead, err = posixStorage.ReadAll(testCase.volume, testCase.path)
		if err != testCase.err {
			t.Fatalf("Test %d: Expected err \"%s\", got err \"%s\"", i+1, testCase.err, err)
		}
		if err == nil {
			if string(dataRead) != string([]byte("Hello, World")) {
				t.Errorf("Test %d: Expected the data read to be \"%s\", but instead got \"%s\"", i+1, "Hello, World", string(dataRead))
			}
		}
	}
	// Testing for faulty disk.
	// Setting ioErrCount > maxAllowedIOError.
	if posixType, ok := posixStorage.(*posix); ok {
		// setting the io error count from as specified in the test case.
		posixType.ioErrCount = int32(6)
	} else {
		t.Errorf("Expected the StorageAPI to be of type *posix")
	}
	_, err = posixStorage.ReadAll("abcd", "efg")
	if err != errFaultyDisk {
		t.Errorf("Expected err \"%s\", got err \"%s\"", errFaultyDisk, err)
	}
}

// TestNewPosix all the cases handled in posix storage layer initialization.
func TestNewPosix(t *testing.T) {
	// Temporary dir name.
	tmpDirName := os.TempDir() + "/" + "minio-" + nextSuffix()
	// Temporary file name.
	tmpFileName := os.TempDir() + "/" + "minio-" + nextSuffix()
	f, _ := os.Create(tmpFileName)
	f.Close()
	defer os.Remove(tmpFileName)

	// List of all tests for posix initialization.
	testCases := []struct {
		diskPath string
		err      error
	}{
		// Validates input argument cannot be empty.
		{
			"",
			errInvalidArgument,
		},
		// Validates if the directory does not exist and
		// gets automatically created.
		{
			tmpDirName,
			nil,
		},
		// Validates if the disk exists as file and returns error
		// not a directory.
		{
			tmpFileName,
			syscall.ENOTDIR,
		},
	}

	// Validate all test cases.
	for i, testCase := range testCases {
		_, err := newPosix(testCase.diskPath)
		if err != testCase.err {
			t.Fatalf("Test %d failed wanted: %s, got: %s", i+1, err, testCase.err)
		}
	}
}

// TestMakeVol - Test validate the logic for creation of new posix volume.
// Asserts the failures too against the expected failures.
func TestMakeVol(t *testing.T) {
	// create posix test setup
	posixStorage, path, err := newPosixTestSetup()
	if err != nil {
		t.Fatalf("Unable to create posix test setup, %s", err)
	}
	defer removeAll(path)

	// Setup test environment.
	// Create a file.
	if err := ioutil.WriteFile(slashpath.Join(path, "vol-as-file"), []byte{}, os.ModePerm); err != nil {
		t.Fatalf("Unable to create file, %s", err)
	}
	// Create a directory.
	if err := os.Mkdir(slashpath.Join(path, "existing-vol"), 0777); err != nil {
		t.Fatalf("Unable to create directory, %s", err)
	}

	testCases := []struct {
		volName     string
		ioErrCount  int
		expectedErr error
	}{
		// Test case - 1.
		// A valid case, volume creation is expected to succeed.
		{
			volName:     "success-vol",
			ioErrCount:  0,
			expectedErr: nil,
		},
		// Test case - 2.
		// Case where a file exists by the name of the volume to be created.
		{
			volName:     "vol-as-file",
			ioErrCount:  0,
			expectedErr: errVolumeExists,
		},
		// Test case - 3.
		{
			volName:     "existing-vol",
			ioErrCount:  0,
			expectedErr: errVolumeExists,
		},
		// Test case - 4.
		// IO error > maxAllowedIOError, should fail with errFaultyDisk.
		{
			volName:     "vol",
			ioErrCount:  6,
			expectedErr: errFaultyDisk,
		},
		// Test case - 5.
		// Test case with invalid volume name.
		{
			volName:     "ab",
			ioErrCount:  0,
			expectedErr: errInvalidArgument,
		},
	}

	for i, testCase := range testCases {
		if posixType, ok := posixStorage.(*posix); ok {
			// setting the io error count from as specified in the test case.
			posixType.ioErrCount = int32(testCase.ioErrCount)
		} else {
			t.Errorf("Expected the StorageAPI to be of type *posix")
		}
		if err := posixStorage.MakeVol(testCase.volName); err != testCase.expectedErr {
			t.Fatalf("Test %d: Expected: \"%s\", got: \"%s\"", i+1, testCase.expectedErr, err)
		}
	}

	// Test for permission denied.
	if runtime.GOOS != "windows" {
		// Initialize posix storage layer for permission denied error.
		posix, err := newPosix("/usr")
		if err != nil {
			t.Fatalf("Unable to initialize posix, %s", err)
		}

		if err := posix.MakeVol("test-vol"); err != errDiskAccessDenied {
			t.Fatalf("expected: %s, got: %s", errDiskAccessDenied, err)
		}
	}
}

// TestDeleteVol - Validates the expected behaviour of posix.DeleteVol for various cases.
func TestDeleteVol(t *testing.T) {
	// create posix test setup
	posixStorage, path, err := newPosixTestSetup()
	if err != nil {
		t.Fatalf("Unable to create posix test setup, %s", err)
	}
	defer removeAll(path)

	// Setup test environment.
	if err = posixStorage.MakeVol("success-vol"); err != nil {
		t.Fatalf("Unable to create volume, %s", err)
	}

	// Test failure cases.
	vol := slashpath.Join(path, "nonempty-vol")
	if err = os.Mkdir(vol, 0777); err != nil {
		t.Fatalf("Unable to create directory, %s", err)
	}
	if err = ioutil.WriteFile(slashpath.Join(vol, "test-file"), []byte{}, os.ModePerm); err != nil {
		t.Fatalf("Unable to create file, %s", err)
	}

	testCases := []struct {
		volName     string
		ioErrCount  int
		expectedErr error
	}{
		// Test case  - 1.
		// A valida case. Empty vol, should be possible to delete.
		{
			volName:     "success-vol",
			ioErrCount:  0,
			expectedErr: nil,
		},
		// Test case - 2.
		// volume is non-existent.
		{
			volName:     "nonexistent-vol",
			ioErrCount:  0,
			expectedErr: errVolumeNotFound,
		},
		// Test case - 3.
		// It shouldn't be possible to delete an non-empty volume, validating the same.
		{
			volName:     "nonempty-vol",
			ioErrCount:  0,
			expectedErr: errVolumeNotEmpty,
		},
		// Test case - 4.
		// IO error > maxAllowedIOError, should fail with errFaultyDisk.
		{
			volName:     "my-disk",
			ioErrCount:  6,
			expectedErr: errFaultyDisk,
		},
		// Test case - 5.
		// Invalid volume name.
		{
			volName:     "ab",
			ioErrCount:  0,
			expectedErr: errInvalidArgument,
		},
	}

	for i, testCase := range testCases {
		if posixType, ok := posixStorage.(*posix); ok {
			// setting the io error count from as specified in the test case.
			posixType.ioErrCount = int32(testCase.ioErrCount)
		} else {
			t.Errorf("Expected the StorageAPI to be of type *posix")
		}
		if err = posixStorage.DeleteVol(testCase.volName); err != testCase.expectedErr {
			t.Fatalf("Test: %d, expected: %s, got: %s", i+1, testCase.expectedErr, err)
		}
	}

	// Test for permission denied.
	if runtime.GOOS != "windows" {
		// Initialize posix storage layer for permission denied error.
		posixStorage, err = newPosix("/usr")
		if err != nil {
			t.Fatalf("Unable to initialize posix, %s", err)
		}

		if err = posixStorage.DeleteVol("bin"); !os.IsPermission(err) {
			t.Fatalf("expected: Permission error, got: %s", err)
		}
	}

	posixDeletedStorage, diskPath, err := newPosixTestSetup()
	if err != nil {
		t.Fatalf("Unable to create posix test setup, %s", err)
	}
	// removing the disk, used to recreate disk not found error.
	removeAll(diskPath)

	// Test for delete on an removed disk.
	// should fail with disk not found.
	err = posixDeletedStorage.DeleteVol("Del-Vol")
	if err != errDiskNotFound {
		t.Errorf("Expected: \"Disk not found\", got \"%s\"", err)
	}
}

// TestStatVol - Tests validate the volume info returned by posix.StatVol() for various inputs.
func TestStatVol(t *testing.T) {
	// create posix test setup
	posixStorage, path, err := newPosixTestSetup()
	if err != nil {
		t.Fatalf("Unable to create posix test setup, %s", err)
	}
	defer removeAll(path)

	// Setup test environment.
	if err = posixStorage.MakeVol("success-vol"); err != nil {
		t.Fatalf("Unable to create volume, %s", err)
	}

	testCases := []struct {
		volName     string
		ioErrCount  int
		expectedErr error
	}{
		// Test case - 1.
		{
			volName:     "success-vol",
			ioErrCount:  0,
			expectedErr: nil,
		},
		// Test case - 2.
		{
			volName:     "nonexistent-vol",
			ioErrCount:  0,
			expectedErr: errVolumeNotFound,
		},
		// Test case - 3.
		{
			volName:     "success-vol",
			ioErrCount:  6,
			expectedErr: errFaultyDisk,
		},
		// Test case - 4.
		{
			volName:     "ab",
			ioErrCount:  0,
			expectedErr: errInvalidArgument,
		},
	}

	for i, testCase := range testCases {
		var volInfo VolInfo
		// setting ioErrCnt from the test case.
		if posixType, ok := posixStorage.(*posix); ok {
			// setting the io error count from as specified in the test case.
			posixType.ioErrCount = int32(testCase.ioErrCount)
		} else {
			t.Errorf("Expected the StorageAPI to be of type *posix")
		}
		volInfo, err = posixStorage.StatVol(testCase.volName)
		if err != testCase.expectedErr {
			t.Fatalf("Test case : %d, Expected: \"%s\", got: \"%s\"", i+1, testCase.expectedErr, err)
		}

		if err == nil {
			if volInfo.Name != volInfo.Name {
				t.Errorf("Test case %d: Expected the volume name to be \"%s\", instead found \"%s\"", i+1, volInfo.Name, volInfo.Name)
			}
		}
	}

	posixDeletedStorage, diskPath, err := newPosixTestSetup()
	if err != nil {
		t.Fatalf("Unable to create posix test setup, %s", err)
	}
	// removing the disk, used to recreate disk not found error.
	removeAll(diskPath)

	// Test for delete on an removed disk.
	// should fail with disk not found.
	_, err = posixDeletedStorage.StatVol("Stat vol")
	if err != errDiskNotFound {
		t.Errorf("Expected: \"Disk not found\", got \"%s\"", err)
	}
}

// TestListVols - Validates the result and the error output for posix volume listing functionality posix.ListVols().
func TestListVols(t *testing.T) {
	// create posix test setup
	posixStorage, path, err := newPosixTestSetup()
	if err != nil {
		t.Fatalf("Unable to create posix test setup, %s", err)
	}

	var volInfo []VolInfo
	// Test empty list vols.
	if volInfo, err = posixStorage.ListVols(); err != nil {
		t.Fatalf("expected: <nil>, got: %s", err)
	} else if len(volInfo) != 0 {
		t.Fatalf("expected: [], got: %s", volInfo)
	}

	// Test non-empty list vols.
	if err = posixStorage.MakeVol("success-vol"); err != nil {
		t.Fatalf("Unable to create volume, %s", err)
	}
	if volInfo, err = posixStorage.ListVols(); err != nil {
		t.Fatalf("expected: <nil>, got: %s", err)
	} else if len(volInfo) != 1 {
		t.Fatalf("expected: 1, got: %d", len(volInfo))
	} else if volInfo[0].Name != "success-vol" {
		t.Errorf("expected: success-vol, got: %s", volInfo[0].Name)
	}
	// setting ioErrCnt to be > maxAllowedIOError.
	// should fail with errFaultyDisk.
	if posixType, ok := posixStorage.(*posix); ok {
		// setting the io error count from as specified in the test case.
		posixType.ioErrCount = int32(6)
	} else {
		t.Errorf("Expected the StorageAPI to be of type *posix")
	}
	if _, err = posixStorage.ListVols(); err != errFaultyDisk {
		t.Errorf("Expected to fail with \"%s\", but instead failed with \"%s\"", errFaultyDisk, err)
	}
	// removing the path and simulating disk failure
	removeAll(path)
	// Resetting the IO error.
	// should fail with errDiskNotFound.
	if posixType, ok := posixStorage.(*posix); ok {
		// setting the io error count from as specified in the test case.
		posixType.ioErrCount = int32(0)
	} else {
		t.Errorf("Expected the StorageAPI to be of type *posix")
	}
	if _, err = posixStorage.ListVols(); err != errDiskNotFound {
		t.Errorf("Expected to fail with \"%s\", but instead failed with \"%s\"", errDiskNotFound, err)
	}
	// creating a new posix instance.
	posixStorage, path, err = newPosixTestSetup()
	if err != nil {
		t.Fatalf("Unable to create posix test setup, %s", err)
	}
	defer removeAll(path)
	// adding the segment of the path length of the volume to be > 255.
	if posixType, ok := posixStorage.(*posix); ok {
		// setting the disk Path with name whose segment length > 255.
		posixType.diskPath = "my-vol-name-0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001"
	} else {
		t.Errorf("Expected the StorageAPI to be of type *posix")
	}
	if _, err = posixStorage.ListVols(); err != errFileNameTooLong {
		t.Errorf("Expected to fail with \"%s\", but instead failed with \"%s\"", errFileNameTooLong, err)
	}

}

// TestPosixListDir -  Tests validate the directory listing functionality provided by posix.ListDir .
func TestPosixListDir(t *testing.T) {
	// create posix test setup
	posixStorage, path, err := newPosixTestSetup()
	if err != nil {
		t.Fatalf("Unable to create posix test setup, %s", err)
	}
	defer removeAll(path)

	// create posix test setup.
	posixDeletedStorage, diskPath, err := newPosixTestSetup()
	if err != nil {
		t.Fatalf("Unable to create posix test setup, %s", err)
	}
	// removing the disk, used to recreate disk not found error.
	removeAll(diskPath)
	// Setup test environment.
	if err = posixStorage.MakeVol("success-vol"); err != nil {
		t.Fatalf("Unable to create volume, %s", err)
	}
	if err = posixStorage.AppendFile("success-vol", "abc/def/ghi/success-file", []byte("Hello, world")); err != nil {
		t.Fatalf("Unable to create file, %s", err)
	}
	if err = posixStorage.AppendFile("success-vol", "abc/xyz/ghi/success-file", []byte("Hello, world")); err != nil {
		t.Fatalf("Unable to create file, %s", err)
	}

	testCases := []struct {
		srcVol   string
		srcPath  string
		ioErrCnt int
		// expected result.
		expectedListDir []string
		expectedErr     error
	}{
		// Test case - 1.
		// valid case with existing volume and file to delete.
		{
			srcVol:          "success-vol",
			srcPath:         "abc",
			ioErrCnt:        0,
			expectedListDir: []string{"def/", "xyz/"},
			expectedErr:     nil,
		},
		// Test case - 1.
		// valid case with existing volume and file to delete.
		{
			srcVol:          "success-vol",
			srcPath:         "abc/def",
			ioErrCnt:        0,
			expectedListDir: []string{"ghi/"},
			expectedErr:     nil,
		},
		// Test case - 1.
		// valid case with existing volume and file to delete.
		{
			srcVol:          "success-vol",
			srcPath:         "abc/def/ghi",
			ioErrCnt:        0,
			expectedListDir: []string{"success-file"},
			expectedErr:     nil,
		},
		// Test case - 2.
		{
			srcVol:      "success-vol",
			srcPath:     "abcdef",
			ioErrCnt:    0,
			expectedErr: errFileNotFound,
		},
		// Test case - 3.
		// Test case with invalid volume name.
		{
			srcVol:      "ab",
			srcPath:     "success-file",
			ioErrCnt:    0,
			expectedErr: errInvalidArgument,
		},
		// Test case - 4.
		// Test case with io error count > max limit.
		{
			srcVol:      "success-vol",
			srcPath:     "success-file",
			ioErrCnt:    6,
			expectedErr: errFaultyDisk,
		},
		// Test case - 5.
		// Test case with non existent volume.
		{
			srcVol:      "non-existent-vol",
			srcPath:     "success-file",
			ioErrCnt:    0,
			expectedErr: errVolumeNotFound,
		},
	}

	for i, testCase := range testCases {
		var dirList []string
		// setting ioErrCnt from the test case.
		if posixType, ok := posixStorage.(*posix); ok {
			// setting the io error count from as specified in the test case.
			posixType.ioErrCount = int32(testCase.ioErrCnt)
		} else {
			t.Errorf("Expected the StorageAPI to be of type *posix")
		}
		dirList, err = posixStorage.ListDir(testCase.srcVol, testCase.srcPath)
		if err != testCase.expectedErr {
			t.Fatalf("Test case %d: Expected: \"%s\", got: \"%s\"", i+1, testCase.expectedErr, err)
		}
		if err == nil {
			for _, expected := range testCase.expectedListDir {
				if !strings.Contains(strings.Join(dirList, ","), expected) {
					t.Errorf("Test case %d: Expected the directory listing to be \"%v\", but got \"%v\"", i+1, testCase.expectedListDir, dirList)
				}
			}
		}
	}

	// Test for permission denied.
	if runtime.GOOS != "windows" {
		// Initialize posix storage layer for permission denied error.
		posixStorage, err = newPosix("/usr")
		if err != nil {
			t.Errorf("Unable to initialize posix, %s", err)
		}

		if err = posixStorage.DeleteFile("bin", "yes"); !os.IsPermission(err) {
			t.Errorf("expected: Permission error, got: %s", err)
		}
	}

	// Test for delete on an removed disk.
	// should fail with disk not found.
	err = posixDeletedStorage.DeleteFile("del-vol", "my-file")
	if err != errDiskNotFound {
		t.Errorf("Expected: \"Disk not found\", got \"%s\"", err)
	}
}

// TestDeleteFile - Series of test cases construct valid and invalid input data and validates the result and the error response.
func TestDeleteFile(t *testing.T) {
	// create posix test setup
	posixStorage, path, err := newPosixTestSetup()
	if err != nil {
		t.Fatalf("Unable to create posix test setup, %s", err)
	}
	defer removeAll(path)

	// create posix test setup
	posixDeletedStorage, diskPath, err := newPosixTestSetup()
	if err != nil {
		t.Fatalf("Unable to create posix test setup, %s", err)
	}
	// removing the disk, used to recreate disk not found error.
	removeAll(diskPath)
	// Setup test environment.
	if err = posixStorage.MakeVol("success-vol"); err != nil {
		t.Fatalf("Unable to create volume, %s", err)
	}
	if err = posixStorage.AppendFile("success-vol", "success-file", []byte("Hello, world")); err != nil {
		t.Fatalf("Unable to create file, %s", err)
	}

	testCases := []struct {
		srcVol      string
		srcPath     string
		ioErrCnt    int
		expectedErr error
	}{
		// Test case - 1.
		// valid case with existing volume and file to delete.
		{
			srcVol:      "success-vol",
			srcPath:     "success-file",
			ioErrCnt:    0,
			expectedErr: nil,
		},
		// Test case - 2.
		// The file was deleted in the last  case, so DeleteFile should fail.
		{
			srcVol:      "success-vol",
			srcPath:     "success-file",
			ioErrCnt:    0,
			expectedErr: errFileNotFound,
		},
		// Test case - 3.
		// Test case with io error count > max limit.
		{
			srcVol:      "success-vol",
			srcPath:     "success-file",
			ioErrCnt:    6,
			expectedErr: errFaultyDisk,
		},
		// Test case - 4.
		// Test case with segment of the volume name > 255.
		{
			srcVol:      "my-obj-del-0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001",
			srcPath:     "success-file",
			ioErrCnt:    0,
			expectedErr: errInvalidArgument,
		},
		// Test case - 5.
		// Test case with non-existent volume.
		{
			srcVol:      "non-existent-vol",
			srcPath:     "success-file",
			ioErrCnt:    0,
			expectedErr: errVolumeNotFound,
		},
		// Test case - 6.
		// Test case with src path segment > 255.
		{
			srcVol:      "success-vol",
			srcPath:     "my-obj-del-0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001",
			ioErrCnt:    0,
			expectedErr: errFileNameTooLong,
		},
	}

	for i, testCase := range testCases {
		// setting ioErrCnt from the test case.
		if posixType, ok := posixStorage.(*posix); ok {
			// setting the io error count from as specified in the test case.
			posixType.ioErrCount = int32(testCase.ioErrCnt)
		} else {
			t.Errorf("Expected the StorageAPI to be of type *posix")
		}
		if err = posixStorage.DeleteFile(testCase.srcVol, testCase.srcPath); err != testCase.expectedErr {
			t.Errorf("Test case %d: Expected: \"%s\", got: \"%s\"", i+1, testCase.expectedErr, err)
		}
	}

	// Test for permission denied.
	if runtime.GOOS != "windows" {
		// Initialize posix storage layer for permission denied error.
		posixStorage, err = newPosix("/usr")
		if err != nil {
			t.Errorf("Unable to initialize posix, %s", err)
		}

		if err = posixStorage.DeleteFile("bin", "yes"); !os.IsPermission(err) {
			t.Errorf("expected: Permission error, got: %s", err)
		}
	}

	// Test for delete on an removed disk.
	// should fail with disk not found.
	err = posixDeletedStorage.DeleteFile("del-vol", "my-file")
	if err != errDiskNotFound {
		t.Errorf("Expected: \"Disk not found\", got \"%s\"", err)
	}
}

// TestReadFile - Tests posix.ReadFile with wide range of cases and asserts the result and error response.
func TestReadFile(t *testing.T) {
	// create posix test setup
	posixStorage, path, err := newPosixTestSetup()
	if err != nil {
		t.Fatalf("Unable to create posix test setup, %s", err)
	}
	defer removeAll(path)

	volume := "success-vol"
	// Setup test environment.
	if err = posixStorage.MakeVol(volume); err != nil {
		t.Fatalf("Unable to create volume, %s", err)
	}

	// Create directory to make errIsNotRegular
	if err = os.Mkdir(slashpath.Join(path, "success-vol", "object-as-dir"), 0777); err != nil {
		t.Fatalf("Unable to create directory, %s", err)
	}

	testCases := []struct {
		volume      string
		fileName    string
		offset      int64
		bufSize     int
		expectedBuf []byte
		expectedErr error
	}{
		// Successful read at offset 0 and proper buffer size. - 1
		{
			volume, "myobject", 0, 5,
			[]byte("hello"), nil,
		},
		// Success read at hierarchy. - 2
		{
			volume, "path/to/my/object", 0, 5,
			[]byte("hello"), nil,
		},
		// One path segment length is 255 chars long. - 3
		{
			volume, "path/to/my/object000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001",
			0, 5, []byte("hello"), nil},
		// Whole path is 1024 characters long, success case. - 4
		{
			volume, "level0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001/level0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000002/level0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000003/object000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001",
			0, 5, []byte("hello"),
			func() error {
				// On darwin HFS does not support > 1024 characters.
				if runtime.GOOS == "darwin" {
					return errFileNameTooLong
				}
				// On all other platforms return success.
				return nil
			}(),
		},
		// Object is a directory. - 5
		{
			volume, "object-as-dir",
			0, 5, nil, errIsNotRegular},
		// One path segment length is > 255 chars long. - 6
		{
			volume, "path/to/my/object0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001",
			0, 5, nil, errFileNameTooLong},
		// Path length is > 1024 chars long. - 7
		{
			volume, "level0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001/level0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000002/level0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000003/object000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001",
			0, 5, nil, errFileNameTooLong},
		// Buffer size greater than object size. - 8
		{
			volume, "myobject", 0, 16,
			[]byte("hello, world"),
			io.ErrUnexpectedEOF,
		},
		// Reading from an offset success. - 9
		{
			volume, "myobject", 7, 5,
			[]byte("world"), nil,
		},
		// Reading from an object but buffer size greater. - 10
		{
			volume, "myobject",
			7, 8,
			[]byte("world"),
			io.ErrUnexpectedEOF,
		},
		// Seeking into a wrong offset, return PathError. - 11
		{
			volume, "myobject",
			-1, 5,
			nil,
			func() error {
				if runtime.GOOS == "windows" {
					return &os.PathError{
						Op:   "seek",
						Path: preparePath(slashpath.Join(path, "success-vol", "myobject")),
						Err:  errors.New("An attempt was made to move the file pointer before the beginning of the file."),
					}
				}
				return &os.PathError{
					Op:   "seek",
					Path: preparePath(slashpath.Join(path, "success-vol", "myobject")),
					Err:  os.ErrInvalid,
				}
			}(),
		},
		// Seeking ahead returns io.EOF. - 12
		{
			volume, "myobject", 14, 1, nil, io.EOF,
		},
		// Empty volume name. - 13
		{
			"", "myobject", 14, 1, nil, errInvalidArgument,
		},
		// Empty filename name. - 14
		{
			volume, "", 14, 1, nil, errIsNotRegular,
		},
		// Non existent volume name - 15.
		{
			"abcd", "", 14, 1, nil, errVolumeNotFound,
		},
		// Non existent filename - 16.
		{
			volume, "abcd", 14, 1, nil, errFileNotFound,
		},
	}

	// Create all files needed during testing.
	appendFiles := testCases[:4]

	// Create test files for further reading.
	for i, appendFile := range appendFiles {
		err = posixStorage.AppendFile(volume, appendFile.fileName, []byte("hello, world"))
		if err != appendFile.expectedErr {
			t.Fatalf("Creating file failed: %d %#v, expected: %s, got: %s", i+1, appendFile, appendFile.expectedErr, err)
		}
	}

	// Following block validates all ReadFile test cases.
	for i, testCase := range testCases {
		var n int64
		// Common read buffer.
		var buf = make([]byte, testCase.bufSize)
		n, err = posixStorage.ReadFile(testCase.volume, testCase.fileName, testCase.offset, buf)
		if err != nil && testCase.expectedErr != nil {
			// Validate if the type string of the errors are an exact match.
			if err.Error() != testCase.expectedErr.Error() {
				t.Errorf("Case: %d %#v, expected: %s, got: %s", i+1, testCase, testCase.expectedErr, err)
			}
			// Err unexpected EOF special case, where we verify we have provided a larger
			// buffer than the data itself, but the results are in-fact valid. So we validate
			// this error condition specifically treating it as a good condition with valid
			// results. In this scenario return 'n' is always lesser than the input buffer.
			if err == io.ErrUnexpectedEOF {
				if !bytes.Equal(testCase.expectedBuf, buf[:n]) {
					t.Errorf("Case: %d %#v, expected: \"%s\", got: \"%s\"", i+1, testCase, string(testCase.expectedBuf), string(buf[:testCase.bufSize]))
				}
				if n > int64(len(buf)) {
					t.Errorf("Case: %d %#v, expected: %d, got: %d", i+1, testCase, testCase.bufSize, n)
				}
			}
		}
		// ReadFile has returned success, but our expected error is non 'nil'.
		if err == nil && err != testCase.expectedErr {
			t.Errorf("Case: %d %#v, expected: %s, got :%s", i+1, testCase, testCase.expectedErr, err)
		}
		// Expected error retured, proceed further to validate the returned results.
		if err == nil && err == testCase.expectedErr {
			if !bytes.Equal(testCase.expectedBuf, buf) {
				t.Errorf("Case: %d %#v, expected: \"%s\", got: \"%s\"", i+1, testCase, string(testCase.expectedBuf), string(buf[:testCase.bufSize]))
			}
			if n != int64(testCase.bufSize) {
				t.Errorf("Case: %d %#v, expected: %d, got: %d", i+1, testCase, testCase.bufSize, n)
			}
		}
	}

	// Test for permission denied.
	if runtime.GOOS == "linux" {
		// Initialize posix storage layer for permission denied error.
		posixStorage, err = newPosix("/")
		if err != nil {
			t.Errorf("Unable to initialize posix, %s", err)
		}
		if err == nil {
			// Common read buffer.
			var buf = make([]byte, 10)
			if _, err = posixStorage.ReadFile("proc", "1/fd", 0, buf); err != errFileAccessDenied {
				t.Errorf("expected: %s, got: %s", errFileAccessDenied, err)
			}
		}
	}

	// Testing for faulty disk.
	// setting ioErrCnt to 6.
	// should fail with errFaultyDisk.
	if posixType, ok := posixStorage.(*posix); ok {
		// setting the io error count from as specified in the test case.
		posixType.ioErrCount = int32(6)
		// Common read buffer.
		var buf = make([]byte, 10)
		_, err = posixType.ReadFile("abc", "yes", 0, buf)
		if err != errFaultyDisk {
			t.Fatalf("Expected \"Faulty Disk\", got: \"%s\"", err)
		}
	} else {
		t.Fatalf("Expected the StorageAPI to be of type *posix")
	}
}

// Test posix.AppendFile()
func TestAppendFile(t *testing.T) {
	// create posix test setup
	posixStorage, path, err := newPosixTestSetup()
	if err != nil {
		t.Fatalf("Unable to create posix test setup, %s", err)
	}
	defer removeAll(path)

	// Setup test environment.
	if err = posixStorage.MakeVol("success-vol"); err != nil {
		t.Fatalf("Unable to create volume, %s", err)
	}

	// Create directory to make errIsNotRegular
	if err = os.Mkdir(slashpath.Join(path, "success-vol", "object-as-dir"), 0777); err != nil {
		t.Fatalf("Unable to create directory, %s", err)
	}

	testCases := []struct {
		fileName    string
		expectedErr error
	}{
		{"myobject", nil},
		{"path/to/my/object", nil},
		// Test to append to previously created file.
		{"myobject", nil},
		// Test to use same path of previously created file.
		{"path/to/my/testobject", nil},
		// One path segment length is 255 chars long.
		{"path/to/my/object000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001", nil},
		{"object-as-dir", errIsNotRegular},
		// path segment uses previously uploaded object.
		{"myobject/testobject", errFileAccessDenied},
		// One path segment length is > 255 chars long.
		{"path/to/my/object0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001", errFileNameTooLong},
		// path length is > 1024 chars long.
		{"level0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001/level0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000002/level0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000003/object000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001", errFileNameTooLong},
	}

	// Add path length > 1024 test specially as OS X system does not support 1024 long path.
	err = errFileNameTooLong
	if runtime.GOOS != "darwin" {
		err = nil
	}
	// path length is 1024 chars long.
	testCases = append(testCases, struct {
		fileName    string
		expectedErr error
	}{"level0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001/level0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000002/level0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000003/object000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001", err})

	for _, testCase := range testCases {
		if err = posixStorage.AppendFile("success-vol", testCase.fileName, []byte("hello, world")); err != testCase.expectedErr {
			t.Errorf("Case: %s, expected: %s, got: %s", testCase, testCase.expectedErr, err)
		}
	}

	// Test for permission denied.
	if runtime.GOOS != "windows" {
		// Initialize posix storage layer for permission denied error.
		posixStorage, err = newPosix("/usr")
		if err != nil {
			t.Fatalf("Unable to initialize posix, %s", err)
		}

		if err = posixStorage.AppendFile("bin", "yes", []byte("hello, world")); !os.IsPermission(err) {
			t.Errorf("expected: Permission error, got: %s", err)
		}
	}
	// Test case with invalid volume name.
	// A valid volume name should be atleast of size 3.
	err = posixStorage.AppendFile("bn", "yes", []byte("hello, world"))
	if err != errInvalidArgument {
		t.Fatalf("expected: \"Invalid argument error\", got: \"%s\"", err)
	}

	// Test case with IO error count > max limit.

	// setting ioErrCnt to 6.
	// should fail with errFaultyDisk.
	if posixType, ok := posixStorage.(*posix); ok {
		// setting the io error count from as specified in the test case.
		posixType.ioErrCount = int32(6)
		err = posixType.AppendFile("abc", "yes", []byte("hello, world"))
		if err != errFaultyDisk {
			t.Fatalf("Expected \"Faulty Disk\", got: \"%s\"", err)
		}
	} else {
		t.Fatalf("Expected the StorageAPI to be of type *posix")
	}
}

// Test posix.RenameFile()
func TestRenameFile(t *testing.T) {
	// create posix test setup
	posixStorage, path, err := newPosixTestSetup()
	if err != nil {
		t.Fatalf("Unable to create posix test setup, %s", err)
	}
	defer removeAll(path)

	// Setup test environment.
	if err := posixStorage.MakeVol("src-vol"); err != nil {
		t.Fatalf("Unable to create volume, %s", err)
	}

	if err := posixStorage.MakeVol("dest-vol"); err != nil {
		t.Fatalf("Unable to create volume, %s", err)
	}

	if err := posixStorage.AppendFile("src-vol", "file1", []byte("Hello, world")); err != nil {
		t.Fatalf("Unable to create file, %s", err)
	}

	if err := posixStorage.AppendFile("src-vol", "file2", []byte("Hello, world")); err != nil {
		t.Fatalf("Unable to create file, %s", err)
	}
	if err := posixStorage.AppendFile("src-vol", "file3", []byte("Hello, world")); err != nil {
		t.Fatalf("Unable to create file, %s", err)
	}
	if err := posixStorage.AppendFile("src-vol", "file4", []byte("Hello, world")); err != nil {
		t.Fatalf("Unable to create file, %s", err)
	}

	if err := posixStorage.AppendFile("src-vol", "file5", []byte("Hello, world")); err != nil {
		t.Fatalf("Unable to create file, %s", err)
	}
	if err := posixStorage.AppendFile("src-vol", "path/to/file1", []byte("Hello, world")); err != nil {
		t.Fatalf("Unable to create file, %s", err)
	}

	testCases := []struct {
		srcVol      string
		destVol     string
		srcPath     string
		destPath    string
		ioErrCnt    int
		expectedErr error
	}{
		// Test case - 1.
		{
			srcVol:      "src-vol",
			destVol:     "dest-vol",
			srcPath:     "file1",
			destPath:    "file-one",
			ioErrCnt:    0,
			expectedErr: nil,
		},
		// Test case - 2.
		{
			srcVol:      "src-vol",
			destVol:     "dest-vol",
			srcPath:     "path/",
			destPath:    "new-path/",
			ioErrCnt:    0,
			expectedErr: nil,
		},
		// Test case - 3.
		// Test to overwrite destination file.
		{
			srcVol:      "src-vol",
			destVol:     "dest-vol",
			srcPath:     "file2",
			destPath:    "file-one",
			ioErrCnt:    0,
			expectedErr: nil,
		},
		// Test case - 4.
		// Test case with io error count set to 1.
		// expected not to fail.
		{
			srcVol:      "src-vol",
			destVol:     "dest-vol",
			srcPath:     "file3",
			destPath:    "file-two",
			ioErrCnt:    1,
			expectedErr: nil,
		},
		// Test case - 5.
		// Test case with io error count set to maximum allowed count.
		// expected not to fail.
		{
			srcVol:      "src-vol",
			destVol:     "dest-vol",
			srcPath:     "file4",
			destPath:    "file-three",
			ioErrCnt:    5,
			expectedErr: nil,
		},
		// Test case - 6.
		// Test case with non-existent source file.
		{
			srcVol:      "src-vol",
			destVol:     "dest-vol",
			srcPath:     "non-existent-file",
			destPath:    "file-three",
			ioErrCnt:    0,
			expectedErr: errFileNotFound,
		},
		// Test case - 7.
		// Test to check failure of source and destination are not same type.
		{
			srcVol:      "src-vol",
			destVol:     "dest-vol",
			srcPath:     "path/",
			destPath:    "file-one",
			ioErrCnt:    0,
			expectedErr: errFileAccessDenied,
		},
		// Test case - 8.
		// Test to check failure of destination directory exists.
		{
			srcVol:      "src-vol",
			destVol:     "dest-vol",
			srcPath:     "path/",
			destPath:    "new-path/",
			ioErrCnt:    0,
			expectedErr: errFileAccessDenied,
		},
		// Test case - 9.
		// Test case with io error count is greater than maxAllowedIOError.
		{
			srcVol:      "src-vol",
			destVol:     "dest-vol",
			srcPath:     "path/",
			destPath:    "new-path/",
			ioErrCnt:    6,
			expectedErr: errFaultyDisk,
		},
		// Test case - 10.
		// Test case with source being a file and destination being a folder.
		// Either both have to be files or directories.
		// Expecting to fail with `errFileAccessDenied`.
		{
			srcVol:      "src-vol",
			destVol:     "dest-vol",
			srcPath:     "file4",
			destPath:    "new-path/",
			ioErrCnt:    0,
			expectedErr: errFileAccessDenied,
		},
		// Test case - 11.
		// Test case with non-existent source volume.
		// Expecting to fail with `errVolumeNotFound`.
		{
			srcVol:      "src-vol-non-existent",
			destVol:     "dest-vol",
			srcPath:     "file4",
			destPath:    "new-path/",
			ioErrCnt:    0,
			expectedErr: errVolumeNotFound,
		},
		// Test case - 12.
		// Test case with non-existent destination volume.
		// Expecting to fail with `errVolumeNotFound`.
		{
			srcVol:      "src-vol",
			destVol:     "dest-vol-non-existent",
			srcPath:     "file4",
			destPath:    "new-path/",
			ioErrCnt:    0,
			expectedErr: errVolumeNotFound,
		},
		// Test case - 13.
		// Test case with invalid src volume name. Length should be atleast 3.
		// Expecting to fail with `errInvalidArgument`.
		{
			srcVol:      "ab",
			destVol:     "dest-vol-non-existent",
			srcPath:     "file4",
			destPath:    "new-path/",
			ioErrCnt:    0,
			expectedErr: errInvalidArgument,
		},
		// Test case - 14.
		// Test case with invalid destination volume name. Length should be atleast 3.
		// Expecting to fail with `errInvalidArgument`.
		{
			srcVol:      "abcd",
			destVol:     "ef",
			srcPath:     "file4",
			destPath:    "new-path/",
			ioErrCnt:    0,
			expectedErr: errInvalidArgument,
		},
		// Test case - 15.
		// Test case with invalid destination volume name. Length should be atleast 3.
		// Expecting to fail with `errInvalidArgument`.
		{
			srcVol:      "abcd",
			destVol:     "ef",
			srcPath:     "file4",
			destPath:    "new-path/",
			ioErrCnt:    0,
			expectedErr: errInvalidArgument,
		},
		// Test case - 16.
		// Test case with the parent of the destination being a file.
		// expected to fail with `errFileAccessDenied`.
		{
			srcVol:      "src-vol",
			destVol:     "dest-vol",
			srcPath:     "file5",
			destPath:    "file-one/parent-is-file",
			ioErrCnt:    0,
			expectedErr: errFileAccessDenied,
		},
		// Test case - 17.
		// Test case with segment of source file name more than 255.
		// expected not to fail.
		{
			srcVol:      "src-vol",
			destVol:     "dest-vol",
			srcPath:     "path/to/my/object0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001",
			destPath:    "file-six",
			ioErrCnt:    0,
			expectedErr: errFileNameTooLong,
		},
		// Test case - 18.
		// Test case with segment of destination file name more than 255.
		// expected not to fail.
		{
			srcVol:      "src-vol",
			destVol:     "dest-vol",
			srcPath:     "file6",
			destPath:    "path/to/my/object0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001",
			ioErrCnt:    0,
			expectedErr: errFileNameTooLong,
		},
	}

	for i, testCase := range testCases {
		// setting ioErrCnt from the test case.
		if posixType, ok := posixStorage.(*posix); ok {
			// setting the io error count from as specified in the test case.
			posixType.ioErrCount = int32(testCase.ioErrCnt)
		} else {
			t.Fatalf("Expected the StorageAPI to be of type *posix")
		}

		if err := posixStorage.RenameFile(testCase.srcVol, testCase.srcPath, testCase.destVol, testCase.destPath); err != testCase.expectedErr {
			t.Fatalf("Test %d:  Expected the error to be : \"%v\", got: \"%v\".", i+1, testCase.expectedErr, err)
		}
	}
}

// Test posix.StatFile()
func TestStatFile(t *testing.T) {
	// create posix test setup
	posixStorage, path, err := newPosixTestSetup()
	if err != nil {
		t.Fatalf("Unable to create posix test setup, %s", err)
	}
	defer removeAll(path)

	// Setup test environment.
	if err := posixStorage.MakeVol("success-vol"); err != nil {
		t.Fatalf("Unable to create volume, %s", err)
	}

	if err := posixStorage.AppendFile("success-vol", "success-file", []byte("Hello, world")); err != nil {
		t.Fatalf("Unable to create file, %s", err)
	}

	if err := posixStorage.AppendFile("success-vol", "path/to/success-file", []byte("Hello, world")); err != nil {
		t.Fatalf("Unable to create file, %s", err)
	}

	testCases := []struct {
		srcVol      string
		srcPath     string
		ioErrCnt    int
		expectedErr error
	}{
		// Test case - 1.
		// Test case with valid inputs, expected to pass.
		{
			srcVol:      "success-vol",
			srcPath:     "success-file",
			ioErrCnt:    0,
			expectedErr: nil,
		},
		// Test case - 2.
		// Test case with valid inputs, expected to pass.
		{
			srcVol:      "success-vol",
			srcPath:     "path/to/success-file",
			ioErrCnt:    0,
			expectedErr: nil,
		},
		// Test case - 3.
		// Test case with non-existent file.
		{
			srcVol:      "success-vol",
			srcPath:     "nonexistent-file",
			ioErrCnt:    0,
			expectedErr: errFileNotFound,
		},
		// Test case - 4.
		// Test case with non-existent file path.
		{
			srcVol:      "success-vol",
			srcPath:     "path/2/success-file",
			ioErrCnt:    0,
			expectedErr: errFileNotFound,
		},
		// Test case - 5.
		// Test case with path being a directory.
		{
			srcVol:      "success-vol",
			srcPath:     "path",
			ioErrCnt:    0,
			expectedErr: errFileNotFound,
		},
		// Test case - 6.
		// Test case with io error count > max limit.
		{
			srcVol:      "success-vol",
			srcPath:     "success-file",
			ioErrCnt:    6,
			expectedErr: errFaultyDisk,
		},
		// Test case - 7.
		// Test case with non existent volume.
		{
			srcVol:      "non-existent-vol",
			srcPath:     "success-file",
			ioErrCnt:    0,
			expectedErr: errVolumeNotFound,
		},
	}

	for i, testCase := range testCases {
		// setting ioErrCnt from the test case.
		if posixType, ok := posixStorage.(*posix); ok {
			// setting the io error count from as specified in the test case.
			posixType.ioErrCount = int32(testCase.ioErrCnt)
		} else {
			t.Errorf("Expected the StorageAPI to be of type *posix")
		}
		if _, err := posixStorage.StatFile(testCase.srcVol, testCase.srcPath); err != testCase.expectedErr {
			t.Fatalf("Test case %d: Expected: \"%s\", got: \"%s\"", i+1, testCase.expectedErr, err)
		}
	}
}