netbeans.apache.org/src/content/wiki/UsingFileSystemsMasterfs.asciidoc

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= UsingFileSystemsMasterfs
:jbake-type: wiki
:jbake-tags: wiki, devfaq, needsreview
:jbake-status: published
:syntax: true
:description: APITest SIGTest NetBeans
:icons: font
:source-highlighter: pygments
:toc: left
:toc-title:
:experimental:

You can use the Filesystems API freely in unit tests. For example:

[source, java]
----
private FileObject d;
protected void setUp() throws Exception {
    clearWorkDir();
    d = FileUtil.toFileObject(getWorkDir());
    assertNotNull(d);
}
----

If you try to run the above code, by default you will get an assertion error in setUp: `toFileObject` returns `null`. 

This is because you need the "Master Filesystem module" available in order to translate Files into FileObjects. 

Add to your `project.xml`:

[source, xml]
----
<!-- if not already there:
            <test-dependencies>
                <test-type>
                    <name>unit</name>
-->
                    <test-dependency>
                        <code-name-base>org.netbeans.modules.masterfs</code-name-base>
                    </test-dependency>
<!-- if not already there:
                </test-type>
            </test-dependencies>
-->
----

Changes made using the Filesystems API should fire change events synchronously, which is helpful for testing code which listens for file changes.