bisync: add to integration tests - fixes #7665

This change officially adds bisync to the nightly integration tests for all
backends.

This will be part of giving us the confidence to take bisync out of beta.

A number of fixes have been added to account for features which can differ on
different backends -- for example, hash types / modtime support, empty
directories, unicode normalization, and unimportant differences in log output.
We will likely find that more of these are needed once we start running these
with the full set of remotes.

Additionally, bisync's extremely sensitive tests revealed a few bugs in other
backends that weren't previously covered by other tests. Fixes for those issues
have been submitted on the following separate PRs (and bisync test failures will
be expected until they are merged):

- #7670 memory: fix deadlock in operations.Purge
- #7688 memory: fix incorrect list entries when rooted at subdirectory
- #7690 memory: fix dst mutating src after server-side copy
- #7692 dropbox: fix chunked uploads when size <= chunkSize

Relatedly, workarounds have been put in place for the following backend
limitations that are unsolvable for the time being:

- #3262 drive is sometimes aware of trashed files/folders when it shouldn't be
- #6199 dropbox can't handle emojis and certain other characters
- #4590 onedrive API has longstanding bug for conflictBehavior=replace in
	server-side copy/move

fs/operations/operations.go

@@ -223,8 +223,10 @@ func logModTimeUpload(dst fs.Object) {
 }
 
 // EqualFn allows replacing Equal() with a custom function during NeedTransfer()
-type EqualFn func(ctx context.Context, src fs.ObjectInfo, dst fs.Object) bool
-type equalFnContextKey struct{}
+type (
+	EqualFn           func(ctx context.Context, src fs.ObjectInfo, dst fs.Object) bool
+	equalFnContextKey struct{}
+)
 
 var equalFnKey = equalFnContextKey{}
 
@@ -451,7 +453,7 @@ func move(ctx context.Context, fdst fs.Fs, dst fs.Object, remote string, src fs.
 				}
 			} else if needsMoveCaseInsensitive(fdst, fdst, remote, src.Remote(), false) {
 				doMove = func(ctx context.Context, src fs.Object, remote string) (fs.Object, error) {
-					return moveCaseInsensitive(ctx, fdst, fdst, remote, src.Remote(), false, src)
+					return MoveCaseInsensitive(ctx, fdst, fdst, remote, src.Remote(), false, src)
 				}
 			}
 		}
@@ -1453,9 +1455,7 @@ func Rmdirs(ctx context.Context, f fs.Fs, dir string, leaveRoot bool) error {
 		}
 	}
 
-	var (
-		errCount = errcount.New()
-	)
+	errCount := errcount.New()
 	// Delete all directories at the same level in parallel
 	for level := len(toDelete) - 1; level >= 0; level-- {
 		dirs := toDelete[level]
@@ -1775,7 +1775,6 @@ func copyURLFn(ctx context.Context, dstFileName string, url string, autoFilename
 
 // CopyURL copies the data from the url to (fdst, dstFileName)
 func CopyURL(ctx context.Context, fdst fs.Fs, dstFileName string, url string, autoFilename, dstFileNameFromHeader bool, noClobber bool) (dst fs.Object, err error) {
-
 	err = copyURLFn(ctx, dstFileName, url, autoFilename, dstFileNameFromHeader, func(ctx context.Context, dstFileName string, in io.ReadCloser, size int64, modTime time.Time) (err error) {
 		if noClobber {
 			_, err = fdst.NewObject(ctx, dstFileName)
@@ -1852,16 +1851,13 @@ func needsMoveCaseInsensitive(fdst fs.Fs, fsrc fs.Fs, dstFileName string, srcFil
 	return !cp && fdst.Name() == fsrc.Name() && fdst.Features().CaseInsensitive && dstFileName != srcFileName && strings.EqualFold(dstFilePath, srcFilePath)
 }
 
-// Special case for changing case of a file on a case insensitive remote
+// MoveCaseInsensitive handles changing case of a file on a case insensitive remote.
 // This will move the file to a temporary name then
 // move it back to the intended destination. This is required
 // to avoid issues with certain remotes and avoid file deletion.
 // returns nil, nil if !needsMoveCaseInsensitive.
 // this does not account a transfer -- the caller should do that if desired.
-func moveCaseInsensitive(ctx context.Context, fdst fs.Fs, fsrc fs.Fs, dstFileName string, srcFileName string, cp bool, srcObj fs.Object) (newDst fs.Object, err error) {
-	if !needsMoveCaseInsensitive(fdst, fsrc, dstFileName, srcFileName, cp) {
-		return nil, nil
-	}
+func MoveCaseInsensitive(ctx context.Context, fdst fs.Fs, fsrc fs.Fs, dstFileName string, srcFileName string, cp bool, srcObj fs.Object) (newDst fs.Object, err error) {
 	logger, _ := GetLogger(ctx)
 
 	// Choose operations
@@ -1947,7 +1943,7 @@ func moveOrCopyFile(ctx context.Context, fdst fs.Fs, fsrc fs.Fs, dstFileName str
 		defer func() {
 			tr.Done(ctx, err)
 		}()
-		_, err = moveCaseInsensitive(ctx, fdst, fsrc, dstFileName, srcFileName, cp, srcObj)
+		_, err = MoveCaseInsensitive(ctx, fdst, fsrc, dstFileName, srcFileName, cp, srcObj)
 		return err
 	}