Factor out TempFile class and reuse it in other tests

Ensure we don't leave "mytext.dat" and "test.txt" lying around in any
directory the tests are run from by ensuring that these files are
destroyed by the test code using them.

tests/streams/textstreamtest.cpp

@@ -31,6 +31,8 @@
     #include "wx/mstream.h"
 #endif // wxUSE_UNICODE
 
+#include "testfile.h"
+
 // ----------------------------------------------------------------------------
 // test class
 // ----------------------------------------------------------------------------
@@ -105,7 +107,9 @@ TextStreamTestCase::TextStreamTestCase()
 
 void TextStreamTestCase::Endline()
 {
-    wxFileOutputStream* pOutFile = new wxFileOutputStream(wxT("test.txt"));
+    TempFile f("test.txt");
+
+    wxFileOutputStream* pOutFile = new wxFileOutputStream(f.GetName());
     wxTextOutputStream* pOutText = new wxTextOutputStream(*pOutFile);
     *pOutText   << wxT("Test text") << endl
                 << wxT("More Testing Text (There should be newline before this)");
@@ -113,7 +117,7 @@ void TextStreamTestCase::Endline()
     delete pOutText;
     delete pOutFile;
 
-    wxFileInputStream* pInFile = new wxFileInputStream(wxT("test.txt"));
+    wxFileInputStream* pInFile = new wxFileInputStream(f.GetName());
 
     char szIn[9 + NEWLINELEN];
 
@@ -147,8 +151,10 @@ void TextStreamTestCase::MiscTests()
 template <typename T>
 static void DoTestRoundTrip(const T *values, size_t numValues)
 {
+    TempFile f("test.txt");
+
     {
-        wxFileOutputStream fileOut(wxT("test.txt"));
+        wxFileOutputStream fileOut(f.GetName());
         wxTextOutputStream textOut(fileOut);
 
         for ( size_t n = 0; n < numValues; n++ )
@@ -158,7 +164,7 @@ static void DoTestRoundTrip(const T *values, size_t numValues)
     }
 
     {
-        wxFileInputStream fileIn(wxT("test.txt"));
+        wxFileInputStream fileIn(f.GetName());
         wxTextInputStream textIn(fileIn);
 
         T value;