fstests: List missing dir must return ErrorDirNotFound for non bucket based remotes

List or ListR of an non existent directory must return
ErrorDirNotFound for non bucket based remotes.  For bucket based
remotes it may return ErrorDirNotFound or it may return no error and
no entries.

cmd/ls/lshelp/lshelp.go

@@ -19,4 +19,8 @@ There are several related list commands
 Note that ` + "`ls`,`lsl`,`lsd`" + ` all recurse by default - use "--max-depth 1" to stop the recursion.
 
 The other list commands ` + "`lsf`,`lsjson`" + ` do not recurse by default - use "-R" to make them recurse.
+
+Listing a non existent directory will produce an error except for
+remotes which can't have empty directories (eg s3, swift, gcs, etc -
+the bucket based remotes).
 `

fstest/fstests/fstests.go

@@ -335,6 +335,27 @@ func Run(t *testing.T, opt *Opt) {
 		TestFsListDirEmpty(t)
 	})
 
+	// TestFsListDirNotFound tests listing the directories from an empty directory
+	TestFsListDirNotFound := func(t *testing.T) {
+		skipIfNotOk(t)
+		objs, dirs, err := walk.GetAll(remote, "does not exist", true, 1)
+		if !remote.Features().CanHaveEmptyDirectories {
+			if err != fs.ErrorDirNotFound {
+				assert.NoError(t, err)
+				assert.Equal(t, 0, len(objs)+len(dirs))
+			}
+		} else {
+			assert.Equal(t, fs.ErrorDirNotFound, err)
+		}
+	}
+	t.Run("TestFsListDirNotFound", TestFsListDirNotFound)
+
+	// TestFsListRDirNotFound tests listing the directories from an empty directory using ListR
+	t.Run("TestFsListRDirNotFound", func(t *testing.T) {
+		defer skipIfNotListR(t)()
+		TestFsListDirNotFound(t)
+	})
+
 	// TestFsNewObjectNotFound tests not finding a object
 	t.Run("TestFsNewObjectNotFound", func(t *testing.T) {
 		skipIfNotOk(t)
@@ -666,10 +687,9 @@ func Run(t *testing.T, opt *Opt) {
 		require.NoError(t, err)
 
 		// check remotes
-		// FIXME: Prints errors.
 		// remote should not exist here
 		_, err = remote.List("")
-		require.Equal(t, fs.ErrorDirNotFound, errors.Cause(err))
+		assert.Equal(t, fs.ErrorDirNotFound, errors.Cause(err))
 		//fstest.CheckListingWithPrecision(t, remote, []fstest.Item{}, []string{}, remote.Precision())
 		file1Copy := file1
 		file1Copy.Path = path.Join(newName, file1.Path)