Operate on copies of test documents

...as the SwTextBlocks ctor internally calls SwDOCXReader::MakeEntries ->
BeginPutDoc which wants to open the document read-write.  That would fail if
SRCDIR is a read-only tree.

Change-Id: I433b80bcec53c8ca4282d1f45c941153a4064eb9
Reviewed-on: https://gerrit.libreoffice.org/52053Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

sw/qa/extras/uiwriter/uiwriter.cxx

@@ -522,7 +522,12 @@ SwDoc* SwUiWriterTest::createDoc(const char* pName)
 
 std::unique_ptr<SwTextBlocks> SwUiWriterTest::readDOCXAutotext(const OUString& sFileName, bool bEmpty)
 {
-    OUString rURL = m_directories.getURLFromSrc(DATA_DIRECTORY) + sFileName;
+    utl::TempFile tmp;
+    tmp.EnableKillingFile();
+    OUString rURL = tmp.GetURL();
+    CPPUNIT_ASSERT_EQUAL(
+        osl::FileBase::E_None,
+        osl::File::copy(m_directories.getURLFromSrc(DATA_DIRECTORY) + sFileName, rURL));
 
     SfxMedium aSrcMed(rURL, StreamMode::STD_READ);
     SwDoc* pDoc = createDoc();