Update test helper to use bscale if its present

sunpy/data/test/__init__.py

@@ -112,7 +112,9 @@ def get_dummy_map_from_header(filename):
     """
     filepath = get_test_filepath(filename)
     header = _fits.format_comments_and_history(astropy.io.fits.Header.fromtextfile(filepath))
-    data = np.random.rand(header['NAXIS2'], header['NAXIS1'])
+    data = np.random.randint(low=0, high=100, size = (header['NAXIS2'], header['NAXIS1']))
+    if "BSCALE" in header:
+        data = data * header["BSCALE"] + header["BZERO"]
     if 'BITPIX' in header:
         data = data.astype(astropy.io.fits.BITPIX2DTYPE[header['BITPIX']])
     # NOTE: by reading straight from the data header pair, we are skipping

sunpy/data/test/tests/test_funcs.py

@@ -0,0 +1,17 @@
+from pathlib import Path
+
+import numpy as np
+
+from sunpy.data.test import get_dummy_map_from_header, get_test_filepath
+
+TEST_IRIS_SJI_HEADER = get_test_filepath('iris_l2_20130801_074720_4040000014_SJI_1400_t000.header')
+
+def test_get_dummy_map_from_header_b_scale_zero_applied():
+    # We use the IRIS one since it contains a BZERO and BSCALE in the test header
+    iris_map = get_dummy_map_from_header(Path(TEST_IRIS_SJI_HEADER))
+    assert iris_map.meta["bscale"] == 0.25
+    assert iris_map.meta["bzero"] == 7992
+    # Data from the test header is scaled by BSCALE and BZERO
+    # but the max value it will return is 100 and converted to int
+    # So its 24 instead of 25 due to the rounding
+    assert np.max(iris_map.data) == 8016

sunpy/io/tests/test_fits.py

@@ -7,7 +7,7 @@
 
 import astropy.io.fits as fits
 
-from sunpy.data.test import get_test_data_filenames, get_test_filepath, write_image_file_from_header_file
+from sunpy.data.test import get_test_data_filenames, get_test_filepath
 from sunpy.data.test.waveunit import MEDN_IMAGE, MQ_IMAGE, NA_IMAGE, SVSM_IMAGE
 from sunpy.io import _fits
 from sunpy.util import MetaDict, SunpyMetadataWarning
@@ -17,7 +17,6 @@
 TEST_EIT_HEADER = get_test_filepath('EIT_header/efz20040301.000010_s.header')
 TEST_SWAP_HEADER = get_test_filepath('SWAP/resampled1_swap.header')
 TEST_GONG_HEADER = get_test_filepath('gong_synoptic.header')
-TEST_IRIS_SJI_HEADER = get_test_filepath('iris_l2_20130801_074720_4040000014_SJI_1400_t000.header')
 # Some of the tests images contain an invalid BLANK keyword ignore the warning raised by this
 pytestmark = pytest.mark.filterwarnings("ignore:Invalid 'BLANK' keyword in header")
 
@@ -133,8 +132,6 @@ def test_write_with_metadict_header_astropy(tmpdir):
 
 # Various warnings are thrown in this test, but we just want to check that the code
 # works without exceptions
-
-
 @pytest.mark.filterwarnings('ignore')
 def test_fitsheader():
     """Test that all test data can be converted back to a FITS header."""
@@ -177,20 +174,15 @@ def test_warn_longkey():
     assert 'BADLONGKEY' not in fits.keys()
 
 
-@pytest.mark.filterwarnings("ignore:Error validating header for HDU")
-def test_read_memmap(tmpdir):
-    # We use the IRIS one since it contains a BZERO and BSCALE
-    file_path = write_image_file_from_header_file(Path(TEST_IRIS_SJI_HEADER), Path(tmpdir))
-    memmap_data, memmap_header = _fits.read(file_path, memmap=True)[0]
-    assert memmap_data.base is not None
-    assert isinstance(memmap_data.base, mmap.mmap)
+def test_read_memmap():
+    data, _ = _fits.read(TEST_AIA_IMAGE, memmap=True)[0]
+    assert data.base is not None
+    # Simple check to see if the base is a memory map
+    assert isinstance(data.base, mmap.mmap)
 
-    raw_data, raw_header = _fits.read(file_path, memmap=False)[0]
-    assert raw_data.base is None
+    data, _ = _fits.read(TEST_AIA_IMAGE, memmap=False)[0]
+    assert data.base is None
 
-    # Check we get the same data back
-    np.testing.assert_allclose(memmap_data, raw_data)
-    assert memmap_header == raw_header
 
 def test_merge_multiple_comment_history_entries():
     header = fits.Header()