Fix IERS_Auto logic now that IERS-A is bundled

astropy/utils/iers/iers.py

@@ -165,9 +165,9 @@ class Conf(_config.ConfigNamespace):
 
     auto_download = _config.ConfigItem(
         True,
-        "Enable auto-downloading of the latest IERS data.  If set to False "
-        "then the local IERS-B file will be used by default (even if the "
-        "full IERS file with predictions was already downloaded and cached). "
+        "Enable auto-downloading of the latest IERS-A data.  If set to False "
+        "then the bundled IERS-A file will be used by default (even if a "
+        "newer version of the IERS-A file was already downloaded and cached). "
         "This parameter also controls whether internet resources will be "
         "queried to update the leap second table if the installed version is "
         "out of date. Default is True.",
@@ -545,9 +545,9 @@ class IERS_A(IERS):
 
     Notes
     -----
-    The IERS A file is not part of astropy.  It can be downloaded from
-    ``iers.IERS_A_URL`` or ``iers.IERS_A_URL_MIRROR``. See ``iers.__doc__``
-    for instructions on use in ``Time``, etc.
+    If the package IERS A file (```iers.IERS_A_FILE``) is out of date, a new
+    version can be downloaded from ``iers.IERS_A_URL`` or ``iers.IERS_A_URL_MIRROR``.
+    See ``iers.__doc__`` for instructions on use in ``Time``, etc.
     """
 
     iers_table = None
@@ -758,6 +758,10 @@ class IERS_Auto(IERS_A):
     """
     Provide most-recent IERS data and automatically handle downloading
     of updated values as necessary.
+
+    The returned table combines the IERS-A and IERS-B files, with the data
+    in the IERS-B file considered to be official values and thus superseding
+    values from th IERS-A file at the same times.
     """
 
     iers_table = None
@@ -772,8 +776,8 @@ def open(cls):
         (or non-existent) then it will be downloaded over the network and cached.
 
         If the configuration setting ``astropy.utils.iers.conf.auto_download``
-        is set to False then ``astropy.utils.iers.IERS()`` is returned.  This
-        is normally the IERS-B table that is supplied with astropy.
+        is set to False then the bundled IERS-A table will be used rather than
+        any downloaded version of the IERS-A table.
 
         On the first call in a session, the table will be memoized (in the
         ``iers_table`` class attribute), and further calls to ``open`` will
@@ -786,7 +790,7 @@ def open(cls):
 
         """
         if not conf.auto_download:
-            cls.iers_table = IERS_B.open()
+            cls.iers_table = cls.read()
             return cls.iers_table
 
         all_urls = (conf.iers_auto_url, conf.iers_auto_url_mirror)
@@ -817,8 +821,8 @@ def open(cls):
             # Issue a warning here, perhaps user is offline.  An exception
             # will be raised downstream if actually trying to interpolate
             # predictive values.
-            warn("unable to download valid IERS file, using local IERS-B", IERSWarning)
-            cls.iers_table = IERS_B.open()
+            warn("unable to download valid IERS file, using local IERS-A", IERSWarning)
+            cls.iers_table = cls.read()
 
         return cls.iers_table
 
@@ -932,7 +936,7 @@ def _substitute_iers_b(cls, table):
         IERS-A has IERS-B values included, but for reasons unknown these
         do not match the latest IERS-B values (see comments in #4436).
         Here, we use the bundled astropy IERS-B table to overwrite the values
-        in the downloaded IERS-A table.
+        in the IERS-A table.
         """
         iers_b = IERS_B.open()
         # Substitute IERS-B values for existing B values in IERS-A table

astropy/utils/iers/tests/test_iers.py

@@ -25,27 +25,9 @@
 
 FILE_NOT_FOUND_ERROR = getattr(__builtins__, "FileNotFoundError", OSError)
 
-try:
-    iers.IERS_A.open("finals2000A.all")  # check if IERS_A is available
-except OSError:
-    HAS_IERS_A = False
-else:
-    HAS_IERS_A = True
-
 IERS_A_EXCERPT = get_pkg_data_filename(os.path.join("data", "iers_a_excerpt"))
 
 
-def setup_module():
-    # Need auto_download so that IERS_B won't be loaded and cause tests to
-    # fail. Files to be downloaded are handled appropriately in the tests.
-    iers.conf.auto_download = True
-
-
-def teardown_module():
-    # This setting is to be consistent with astropy/conftest.py
-    iers.conf.auto_download = False
-
-
 class TestBasic:
     """Basic tests that IERS_B returns correct values"""
 
@@ -216,7 +198,6 @@ def test_simple(self):
         assert len(iers_tab[:2]) == 2
 
 
-@pytest.mark.skipif(not HAS_IERS_A, reason="requires IERS_A")
 class TestIERS_A:
     @classmethod
     def teardown_class(self):
@@ -261,6 +242,14 @@ def setup_class(self):
         self.iers_a_url_2 = Path(self.iers_a_file_2).as_uri()
         self.t = Time.now() + TimeDelta(10, format="jd") * np.arange(self.N)
 
+        # This group of tests requires auto downloading to be on
+        iers.conf.auto_download = True
+
+        # auto_download = False is tested in test_IERS_B_parameters_loading_into_IERS_Auto()
+
+    def teardown_class(self):
+        iers.conf.auto_download = False
+
     def teardown_method(self, method):
         """Run this after every test."""
         iers.IERS_Auto.close()
@@ -310,12 +299,6 @@ def test_auto_max_age_minimum(self):
                     iers_table = iers.IERS_Auto.open()
                     _ = iers_table.ut1_utc(self.t.jd1, self.t.jd2)
 
-    def test_no_auto_download(self):
-        with iers.conf.set_temp("auto_download", False):
-            t = iers.IERS_Auto.open()
-        assert type(t) is iers.IERS_B
-
-    @pytest.mark.remote_data
     def test_simple(self):
         with iers.conf.set_temp("iers_auto_url", self.iers_a_url_1):
             dat = iers.IERS_Auto.open()
@@ -380,8 +363,10 @@ def test_simple(self):
             assert dat["MJD"][-1] == (57539.0 + 60) * u.d
 
 
-@pytest.mark.remote_data
 def test_IERS_B_parameters_loading_into_IERS_Auto():
+    # Double-check that auto downloading is off
+    assert not iers.conf.auto_download
+
     A = iers.IERS_Auto.open()
     B = iers.IERS_B.open()
 
@@ -445,35 +430,31 @@ def test_iers_b_dl():
         iers.IERS_B.close()
 
 
-@pytest.mark.remote_data
-def test_iers_out_of_range_handling(tmp_path):
-    # Make sure we don't have IERS-A data available anywhere
-    with set_temp_cache(tmp_path):
-        iers.IERS_A.close()
-        iers.IERS_Auto.close()
-        iers.IERS.close()
+def test_iers_b_out_of_range_handling():
+    # The following error/warning applies only to IERS_B, not to the default IERS_Auto
+    with iers.earth_orientation_table.set(iers.IERS_B.open()):
         now = Time.now()
-        with iers.conf.set_temp("auto_download", False):
-            # Should be fine with built-in IERS_B
-            (now - 300 * u.day).ut1
 
-            # Default is to raise an error
-            match = r"\(some\) times are outside of range covered by IERS table"
-            with pytest.raises(iers.IERSRangeError, match=match):
-                (now + 100 * u.day).ut1
+        # Should be fine with bundled IERS-B
+        (now - 300 * u.day).ut1
 
-            with iers.conf.set_temp("iers_degraded_accuracy", "warn"):
-                with pytest.warns(iers.IERSDegradedAccuracyWarning, match=match):
-                    (now + 100 * u.day).ut1
+        # Default is to raise an error
+        match = r"\(some\) times are outside of range covered by IERS table"
+        with pytest.raises(iers.IERSRangeError, match=match):
+            (now + 100 * u.day).ut1
 
-            with iers.conf.set_temp("iers_degraded_accuracy", "ignore"):
+        with iers.conf.set_temp("iers_degraded_accuracy", "warn"):
+            with pytest.warns(iers.IERSDegradedAccuracyWarning, match=match):
                 (now + 100 * u.day).ut1
 
+        with iers.conf.set_temp("iers_degraded_accuracy", "ignore"):
+            (now + 100 * u.day).ut1
+
 
 @pytest.mark.remote_data
 def test_iers_download_error_handling(tmp_path):
-    # Make sure we don't have IERS-A data available anywhere
-    with set_temp_cache(tmp_path):
+    # Make sure an IERS-A table isn't already loaded
+    with set_temp_cache(tmp_path), iers.conf.set_temp("auto_download", True):
         iers.IERS_A.close()
         iers.IERS_Auto.close()
         iers.IERS.close()
@@ -485,7 +466,7 @@ def test_iers_download_error_handling(tmp_path):
             with iers.conf.set_temp("iers_auto_url_mirror", "https://google.com"):
                 with pytest.warns(iers.IERSWarning) as record:
                     with iers.conf.set_temp("iers_degraded_accuracy", "ignore"):
-                        (now + 100 * u.day).ut1
+                        (now + 400 * u.day).ut1
 
                 assert len(record) == 3
                 assert str(record[0].message).startswith(
@@ -495,7 +476,7 @@ def test_iers_download_error_handling(tmp_path):
                     "malformed IERS table from https://google.com"
                 )
                 assert str(record[2].message).startswith(
-                    "unable to download valid IERS file, using local IERS-B"
+                    "unable to download valid IERS file, using local IERS-A"
                 )
 
 

docs/utils/iers.rst

@@ -94,9 +94,9 @@ that relate to automatic IERS downloading. Four of the most
 important to consider are the following:
 
   auto_download:
-    Enable auto-downloading of the latest IERS data.  If set to ``False`` then
-    the local IERS-A and IERS-B files will be used by default (even if the full
-    IERS file with predictions was already downloaded and cached).  This
+    Enable auto-downloading of the latest IERS-A data.  If set to ``False`` then
+    the bundled IERS-A file will be used by default (even if a newer
+    versions of the IERS-A file was already downloaded and cached).  This
     parameter also controls whether internet resources will be queried to update
     the leap second table if the installed version is out of date.