How to use the memfs.vol.writeFileSync function in memfs

it( 'ignores a package that is not a plugin', async () => {

        vol.mkdirpSync( localPluginDir ); // local
        vol.writeFileSync( localPluginPackageFile, JSON.stringify( pkg ) ); // local

        const pkg2 = { ... pkg }; // copy properties
        pkg2.name += '-non-plugin';
        pkg2[ PLUGIN_PROPERTY ] = undefined; // removes the expected property

        vol.mkdirpSync( join( localModulesDir, pkg2.name ) );
        vol.writeFileSync( join( localModulesDir, pkg2.name, PKG_FILENAME ), JSON.stringify( pkg2 ) );

        const finder: PackageBasedPluginFinder = new PackageBasedPluginFinder( currentDir, fs );
        const pluginData: PluginData[] = await finder.find();
        expect( pluginData ).toHaveLength( 1 );
    } );

it( 'prefers local than global', async () => {

        vol.mkdirpSync( localPluginDir ); // local
        vol.writeFileSync( localPluginPackageFile, JSON.stringify( pkg ) ); // local

        const pkg2 = { ... pkg }; // copy properties

        vol.mkdirpSync( globalPluginDir ); // global
        vol.writeFileSync( globalPluginPackageFile, JSON.stringify( pkg2 ) ); // global

        const finder: PackageBasedPluginFinder = new PackageBasedPluginFinder( currentDir, fs );
        const pluginData: PluginData[] = await finder.find();
        expect( pluginData ).toHaveLength( 1 );

        const first = pluginData[ 0 ];

        expect( first.name ).toEqual( pkg.name );
    } );

it( 'ignores a package that is not a plugin', async () => {

        vol.mkdirpSync( localPluginDir ); // local
        vol.writeFileSync( localPluginPackageFile, JSON.stringify( pkg ) ); // local

        const pkg2 = { ... pkg }; // copy properties
        pkg2.name += '-non-plugin';
        pkg2[ PLUGIN_PROPERTY ] = undefined; // removes the expected property

        vol.mkdirpSync( join( localModulesDir, pkg2.name ) );
        vol.writeFileSync( join( localModulesDir, pkg2.name, PKG_FILENAME ), JSON.stringify( pkg2 ) );

        const finder: PackageBasedPluginFinder = new PackageBasedPluginFinder( currentDir, fs );
        const pluginData: PluginData[] = await finder.find();
        expect( pluginData ).toHaveLength( 1 );
    } );