private void assertHostBindingExists(String bindString) {

        // Extract the host-portion of the volume binding string, accounting for windows platform paths and unix style
        // paths.  For example:
        // C:\Users\foo\Documents\workspaces\docker-maven-plugin\target\test-classes\compose\version:/tmp/version
        // and
        // /Users/foo/workspaces/docker-maven-plugin/target/test-classes/compose/version:/tmp/version

        File file;
        if (bindString.indexOf(":") > 1) {
            // a unix-style path
            file = new File(bindString.substring(0, bindString.indexOf(":")));
        } else {
            // a windows-style path with a drive letter
            file = new File(bindString.substring(0, bindString.indexOf(":", 2)));
        }
        Assertions.assertTrue(file.exists(), "The file '" + file + "' parsed from the volume binding string '" + bindString + "' does not exist!");
    }
Parses the supplied binding string for the host portion, and insures the host portion actually exists on the
filesystem.  Note this method is designed to accommodate both Windows-style and *nix-style absolute paths.
<p>
The {@code docker-compose.yml} used for testing contains volume binding strings which are <em>relative</em>.
When the {@link RunVolumeConfiguration} is built, relative paths in the host portion of the binding string are
resolved to absolute paths.  This method expects a binding string that has already had its relative paths
<em>resolved</em> to absolute paths.  It parses the host portion of the binding string, and asserts that the path
exists on the system.
</p>

@param bindString a volume binding string that contains a host portion that is expected to exist on the local
system
src/test/java/io/fabric8/maven/docker/config/handler/compose/DockerComposeConfigHandlerTest.java