virtcontainers/persist: Improved test coverage 65% to 87.5%

Expanded tests on manager_test.go to cover more lines of code.

Fixes: #259

Signed-off-by: Eduardo Berrocal <eduardo.berrocal@intel.com>

src/runtime/virtcontainers/persist/manager_test.go

@@ -7,7 +7,9 @@
 package persist
 
 import (
+	"errors"
 	"os"
+	"strings"
 	"testing"
 
 	persistapi "github.com/kata-containers/kata-containers/src/runtime/virtcontainers/persist/api"
@@ -20,14 +22,29 @@ func TestGetDriverByName(t *testing.T) {
 	assert.NotNil(t, err)
 	assert.Nil(t, nonexist)
 
+	// testing correct driver is returned
 	fsDriver, err := GetDriverByName("fs")
 	assert.Nil(t, err)
 	assert.NotNil(t, fsDriver)
+
+	// testing case when expErr is set
+	expErr = errors.New("TEST-ERROR")
+	defer func() {
+		expErr = nil
+	}()
+
+	nonexist, err = GetDriverByName("fs")
+	assert.NotNil(t, err)
+	assert.Nil(t, nonexist)
+
+	b := err.Error()
+	assert.True(t, strings.Contains(b, "TEST-ERROR"))
 }
 
 func TestGetDriver(t *testing.T) {
 	assert := assert.New(t)
 
+	// testing correct driver is returned
 	fsd, err := GetDriver()
 	assert.NoError(err)
 
@@ -39,5 +56,32 @@ func TestGetDriver(t *testing.T) {
 	}
 
 	assert.NoError(err)
-	assert.Equal(expectedFS, fsd)
+	assert.Equal(expectedFS, fsd) // driver should match correct one for UID
+
+	// testing case when expErr is set
+	expErr = errors.New("TEST-ERROR")
+	nonexist, err := GetDriver()
+	assert.NotNil(err)
+	assert.Nil(nonexist)
+	expErr = nil
+
+	// testing case when driver can't be found on supportedDrivers variable
+	supportedDriversBU := supportedDrivers
+	supportedDrivers = nil
+	fsd, err = GetDriver()
+	assert.Nil(fsd)
+	assert.NotNil(err)
+	b := err.Error()
+	assert.True(strings.Contains(b, "Could not find a FS driver"))
+	supportedDrivers = supportedDriversBU
+
+	// testing case when mock driver is activated
+	fs.EnableMockTesting(t.TempDir())
+	mock, err := GetDriver()
+	assert.NoError(err)
+	expectedFS, err = fs.MockFSInit(fs.MockStorageRootPath())
+	assert.NoError(err)
+	assert.Equal(expectedFS, mock)
+
+	fs.EnableMockTesting("")
 }