Fixed a failing test when the source directory is on a readonly fs.

tests/gis_tests/gdal_tests/test_raster.py

 import os
+import shutil
 import struct
 import tempfile
 
@@ -541,54 +542,54 @@ class GDALRasterTests(SimpleTestCase):
 
 
 class GDALBandTests(SimpleTestCase):
-    def setUp(self):
-        self.rs_path = os.path.join(os.path.dirname(__file__), '../data/rasters/raster.tif')
-        rs = GDALRaster(self.rs_path)
-        self.band = rs.bands[0]
+    rs_path = os.path.join(os.path.dirname(__file__), '../data/rasters/raster.tif')
 
     def test_band_data(self):
-        pam_file = self.rs_path + '.aux.xml'
-        self.assertEqual(self.band.width, 163)
-        self.assertEqual(self.band.height, 174)
-        self.assertEqual(self.band.description, '')
-        self.assertEqual(self.band.datatype(), 1)
-        self.assertEqual(self.band.datatype(as_string=True), 'GDT_Byte')
-        self.assertEqual(self.band.color_interp(), 1)
-        self.assertEqual(self.band.color_interp(as_string=True), 'GCI_GrayIndex')
-        self.assertEqual(self.band.nodata_value, 15)
+        rs = GDALRaster(self.rs_path)
+        band = rs.bands[0]
+        self.assertEqual(band.width, 163)
+        self.assertEqual(band.height, 174)
+        self.assertEqual(band.description, '')
+        self.assertEqual(band.datatype(), 1)
+        self.assertEqual(band.datatype(as_string=True), 'GDT_Byte')
+        self.assertEqual(band.color_interp(), 1)
+        self.assertEqual(band.color_interp(as_string=True), 'GCI_GrayIndex')
+        self.assertEqual(band.nodata_value, 15)
         if numpy:
-            data = self.band.data()
+            data = band.data()
             assert_array = numpy.loadtxt(
                 os.path.join(os.path.dirname(__file__), '../data/rasters/raster.numpy.txt')
             )
             numpy.testing.assert_equal(data, assert_array)
-            self.assertEqual(data.shape, (self.band.height, self.band.width))
-        try:
-            smin, smax, smean, sstd = self.band.statistics(approximate=True)
+            self.assertEqual(data.shape, (band.height, band.width))
+
+    def test_band_statistics(self):
+        with tempfile.TemporaryDirectory() as tmp_dir:
+            rs_path = os.path.join(tmp_dir, 'raster.tif')
+            shutil.copyfile(self.rs_path, rs_path)
+            rs = GDALRaster(rs_path)
+            band = rs.bands[0]
+            pam_file = rs_path + '.aux.xml'
+            smin, smax, smean, sstd = band.statistics(approximate=True)
             self.assertEqual(smin, 0)
             self.assertEqual(smax, 9)
             self.assertAlmostEqual(smean, 2.842331288343558)
             self.assertAlmostEqual(sstd, 2.3965567248965356)
 
-            smin, smax, smean, sstd = self.band.statistics(approximate=False, refresh=True)
+            smin, smax, smean, sstd = band.statistics(approximate=False, refresh=True)
             self.assertEqual(smin, 0)
             self.assertEqual(smax, 9)
             self.assertAlmostEqual(smean, 2.828326634228898)
             self.assertAlmostEqual(sstd, 2.4260526986669095)
 
-            self.assertEqual(self.band.min, 0)
-            self.assertEqual(self.band.max, 9)
-            self.assertAlmostEqual(self.band.mean, 2.828326634228898)
-            self.assertAlmostEqual(self.band.std, 2.4260526986669095)
+            self.assertEqual(band.min, 0)
+            self.assertEqual(band.max, 9)
+            self.assertAlmostEqual(band.mean, 2.828326634228898)
+            self.assertAlmostEqual(band.std, 2.4260526986669095)
 
             # Statistics are persisted into PAM file on band close
-            self.band = None
+            rs = band = None
             self.assertTrue(os.path.isfile(pam_file))
-        finally:
-            # Close band and remove file if created
-            self.band = None
-            if os.path.isfile(pam_file):
-                os.remove(pam_file)
 
     def test_read_mode_error(self):
         # Open raster in read mode