EphemeralFs

An in memory implementation of java.nio.FileSystem written in java, suitable for testing.

EphemeralFs tries to mimic the behaviour of java.nio.FileSystem for Windows, OS-X and Linux as closely as possible.

EphemeralFsFileSystemChecker allows asserting that all resources are closed, and that all file contents have been properly fsynced.

Getting Started

EphemeralFs is available in maven as com.github.sbridges:ephemeralfs:1.0.1.0 :

	<dependency>
	    <groupId>com.github.sbridges</groupId>
	    <artifactId>ephemeralfs</artifactId>
	    <version>1.0.1.0</version>
	</dependency>

Example

##Unix

        FileSystem fs = EphemeralFsFileSystemBuilder
                .unixFs()
                .build();
                
        Path testDir = fs.getPath("/testDir");
        Files.createDirectory(testDir);
        Files.write(testDir.resolve("cafe"), new byte[] {'c', 'a', 'f', 'e'});

##Windows

        FileSystem fs = EphemeralFsFileSystemBuilder
                .windowsFs()
                .build();
        
        Path testDir = fs.getPath("m:\\windwosTestDir");
        Files.createDirectory(testDir);
        Files.write(testDir.resolve("dir"), new byte[] {'d', 'o', '5'});

##Assertions

        FileSystem fs = EphemeralFsFileSystemBuilder
                .macFs()
                .setRecordStackTracesOnOpen(true)
                .build();
        
        Files.newOutputStream(fs.getPath("/testFile"), StandardOpenOption.CREATE);
        
        //this will throws as the stream above was not closed
        //the AssertionError will contain the stack
        //trace of where the stream was opened
        EphemeralFsFileSystemChecker.assertNoOpenResources(fs);    

What is supported

• Basic file/directory operations such as reading, writing ,moving etc
• InputStream, OutputStream
• SeekableByteChannel, FileChannel, AsynchronousFileChannel
• Symbolic links
• Hard links
• SecureDirectoryStream
• BasicFileAttributes, PosixFileAttributes, DosFileAttributes
• "basic", "dos", "owner", "posix", "unix" file attributes
• WatchService
• Globs
• FileLock
• Maximum file system size
• Checking file system state (all resources closed, all files fsynced)

TODO

• Users/Groups
• File Permissions
• Last access time
• File sizes > 2GB
• FileTypeDetector
• AclFileAttributeView

What can't be supported

Path#toFile is specified to only return a File for the default provider.

FileChannel#map can't be implemented since MappedByteBuffer declares all its methods final.