### Question:
MicroHelper { @Nullable public static String getDocumentRootElementTagName (@Nullable final IMicroDocument aDoc) { if (aDoc != null) { final IMicroElement eRoot = aDoc.getDocumentElement (); if (eRoot != null) return eRoot.getTagName (); } return null; } private  MicroHelper(); @Nonnull static IMicroNode append(@Nonnull final IMicroNode aSrcNode, @Nullable final Object aChild); @Nonnull @SuppressFBWarnings ("IL_INFINITE_LOOP") static String getPath(@Nullable final IMicroNode aNode, @Nonnull final String sSep); @Nullable static String getDocumentRootElementTagName(@Nullable final IMicroDocument aDoc); @Nonnull static IMicroNode convertToMicroNode(@Nonnull final Node aNode); @Nullable static String getChildTextContent(@Nonnull final IMicroElement eParentElement, @Nonnull final String sChildElementName); @Nullable static String getChildTextContentTrimmed(@Nonnull final IMicroElement eParentElement, @Nonnull final String sChildElementName); @Nullable static DSTTYPE getChildTextContentWithConversion(@Nonnull final IMicroElement eParentElement,
                                                                     @Nonnull final String sChildElementName,
                                                                     @Nonnull final Class <DSTTYPE> aDstClass); @Nullable static String getChildTextContent(@Nonnull final IMicroElement eParentElement,
                                            @Nonnull final String sNamespaceURI,
                                            @Nonnull final String sChildElementName); @Nullable static String getChildTextContentTrimmed(@Nonnull final IMicroElement eParentElement,
                                                   @Nonnull final String sNamespaceURI,
                                                   @Nonnull final String sChildElementName); @Nullable static DSTTYPE getChildTextContentWithConversion(@Nonnull final IMicroElement eParentElement,
                                                                     @Nonnull final String sNamespaceURI,
                                                                     @Nonnull final String sChildElementName,
                                                                     @Nonnull final Class <DSTTYPE> aDstClass); @Nonnull @ReturnsMutableCopy static IMicroContainer getAllChildrenAsContainer(@Nonnull final IMicroNode aParent); @Nonnull @ReturnsMutableCopy static IMicroContainer getAllOriginalChildrenAsContainer(@Nonnull final IMicroNode aParent);  }### Answer:
@Test public void testGetDocumentRootElementTagName () { assertNull (MicroHelper.getDocumentRootElementTagName (null)); final IMicroDocument aDoc = new MicroDocument (); assertNull (MicroHelper.getDocumentRootElementTagName (aDoc)); aDoc.appendElement ("root"); assertEquals ("root", MicroHelper.getDocumentRootElementTagName (aDoc)); }