Fix to_checksums with None values in dicts and recursion

Having a `'src': None` entry in a dict for checksums is as valid as
having a `None` entry directly in the list. However the current function
didn't handle it and crashed.
Fix that as well as a few corner cases especially in the recursive case
by introducing a new function for handling checksum entries in the
checksum list and limiting the recursiveness.

Fixes easybuilders#4142

easybuild/framework/easyconfig/types.py

@@ -469,33 +469,51 @@ def to_dependencies(dep_list):
     return [to_dependency(dep) for dep in dep_list]
 
 
-def to_checksums(checksums):
-    """Ensure correct element types for list of checksums: convert list elements to tuples."""
-    res = []
-    for checksum in checksums:
-        # each list entry can be:
-        # * None (indicates no checksum)
-        # * a string (MD5 or SHA256 checksum)
-        # * a tuple with 2 elements: checksum type + checksum value
-        # * a list of checksums (i.e. multiple checksums for a single file)
-        # * a dict (filename to checksum mapping)
-        if isinstance(checksum, string_type):
-            res.append(checksum)
-        elif isinstance(checksum, (list, tuple)):
-            # 2 elements + only string/int values => a checksum tuple
-            if len(checksum) == 2 and all(isinstance(x, (string_type, int)) for x in checksum):
-                res.append(tuple(checksum))
+def _to_checksum(checksum, list_level=0, allow_dict=True):
+    """Ensure the correct element type for each checksum in the checksum list"""
+    # each entry can be:
+    # * None (indicates no checksum)
+    # * a string (MD5, SHA256, ... checksum)
+    # * a list or tuple with 2 elements: checksum type + checksum value
+    # * a list or tuple of checksums (i.e. multiple checksums for a single file)
+    # * a dict (filename to checksum mapping)
+    if checksum is None or isinstance(checksum, string_type):
+        return checksum
+    elif isinstance(checksum, (list, tuple)):
+        if len(checksum) == 2 and isinstance(checksum[0], string_type) and isinstance(checksum[1], (string_type, int)):
+            # 2 elements so either:
+            #  - a checksum tuple (2nd element string or int)
+            #  - 2 alternative checksums (tuple)
+            #  - 2 checksums that must each match (list)
+            # --> Convert to tuple only if we can exclude the 3rd case
+            if not isinstance(checksum[1], string_type) or list_level > 0:
+                return tuple(checksum)
             else:
-                res.append(to_checksums(checksum))
-        elif isinstance(checksum, dict):
-            validated_dict = {}
-            for key, value in checksum.items():
-                validated_dict[key] = to_checksums(value)
-            res.append(validated_dict)
-        else:
-            res.append(checksum)
+                return checksum
+        elif list_level < 2:
+            # Alternative checksums or multiple checksums for a single file
+            # Allowed to nest (at most) 2 times, e.g. [[[type, value]]] == [[(type, value)]]
+            # None is not allowed here
+            if any(x is None for x in checksum):
+                raise ValueError('Unexpected None in ' + str(checksum))
+            if isinstance(checksum, tuple) or list_level > 0:
+                # When we already are in a tuple no further recursion is allowed -> set list_level very high
+                return tuple(_to_checksum(x, list_level=99, allow_dict=allow_dict) for x in checksum)
+            else:
+                return list(_to_checksum(x, list_level=list_level+1, allow_dict=allow_dict) for x in checksum)
+    elif isinstance(checksum, dict) and allow_dict:
+        return {key: _to_checksum(value, allow_dict=False) for key, value in checksum.items()}
 
-    return res
+    # Not returned -> Wrong type/format
+    raise ValueError('Unexpected type of "%s": %s' % (type(checksum), str(checksum)))
+
+
+def to_checksums(checksums):
+    """Ensure correct element types for list of checksums: convert list elements to tuples."""
+    try:
+        return [_to_checksum(checksum) for checksum in checksums]
+    except ValueError as e:
+        raise EasyBuildError('Invalid checksums: %s\n\tError: %s', checksums, e)
 
 
 def ensure_iterable_license_specs(specs):

test/framework/type_checking.py

@@ -172,16 +172,16 @@ def test_check_type_of_param_value_sanity_check_paths(self):
         out = {'files': ['bin/foo', ('bin/bar', 'bin/baz')], 'dirs': [('lib', 'lib64', 'lib32')]}
         self.assertEqual(check_type_of_param_value('sanity_check_paths', inp, auto_convert=True), (True, out))
 
-    def test_check_type_of_param_value_checksums(self):
-        """Test check_type_of_param_value function for checksums."""
+    @staticmethod
+    def get_valid_checksums_values():
+        """Return list of values valid for the 'checksums' EC parameter"""
 
         md5_checksum = 'fa618be8435447a017fd1bf2c7ae9224'
         sha256_checksum1 = 'fa618be8435447a017fd1bf2c7ae922d0428056cfc7449f7a8641edf76b48265'
         sha256_checksum2 = 'b5f9cb06105c1d2d30719db5ffb3ea67da60919fb68deaefa583deccd8813551'
         sha256_checksum3 = '033be54514a03e255df75c5aee8f9e672f663f93abb723444caec8fe43437bde'
-
         # valid values for 'checksums' easyconfig parameters
-        inputs = [
+        return [
             [],
             # single checksum (one file)
             [md5_checksum],
@@ -237,7 +237,11 @@ def test_check_type_of_param_value_checksums(self):
                 {'foo.txt': sha256_checksum1, 'bar.txt': None},
             ],
         ]
-        for inp in inputs:
+
+    def test_check_type_of_param_value_checksums(self):
+        """Test check_type_of_param_value function for checksums."""
+
+        for inp in TypeCheckingTest.get_valid_checksums_values():
             self.assertTrue(check_type_of_param_value('checksums', inp), 'Failed for ' + str(inp))
 
     def test_check_type_of_param_value_patches(self):
@@ -720,19 +724,94 @@ def test_to_sanity_check_paths_dict(self):
 
     def test_to_checksums(self):
         """Test to_checksums function."""
+        # Some hand-crafted examples. Only the types are important, values are for easier verification
         test_inputs = [
-            ['be662daa971a640e40be5c804d9d7d10'],
-            ['be662daa971a640e40be5c804d9d7d10', ('md5', 'be662daa971a640e40be5c804d9d7d10')],
-            [['be662daa971a640e40be5c804d9d7d10', ('md5', 'be662daa971a640e40be5c804d9d7d10')]],
-            [('md5', 'be662daa971a640e40be5c804d9d7d10')],
-            ['be662daa971a640e40be5c804d9d7d10', ('adler32', '0x998410035'), ('crc32', '0x1553842328'),
-             ('md5', 'be662daa971a640e40be5c804d9d7d10'), ('sha1', 'f618096c52244539d0e89867405f573fdb0b55b0'),
-             ('size', 273)],
+            ['checksumvalue'],
+            [('md5', 'md5checksumvalue')],
+            ['file_1_checksum', ('md5', 'file_2_md5_checksum')],
+            # One checksum per file, some with checksum type
+            [
+                'be662daa971a640e40be5c804d9d7d10',
+                ('adler32', '0x998410035'),
+                ('crc32', '0x1553842328'),
+                ('md5', 'be662daa971a640e40be5c804d9d7d10'),
+                ('sha1', 'f618096c52244539d0e89867405f573fdb0b55b0'),
+                # int type as the 2nd value
+                ('size', 273),
+            ],
             # None values should not be filtered out, but left in place
-            [None, 'fa618be8435447a017fd1bf2c7ae922d0428056cfc7449f7a8641edf76b48265', None],
+            [None, 'checksum', None],
+            # Alternative checksums, not to be confused with multiple checksums for a file
+            [('main_checksum', 'alternative_checksum')],
+            [('1st_of_3', '2nd_of_3', '3rd_of_3')],
+            # Lists must be kept: This means all must match
+            [['checksum_1_in_list']],
+            [['checksum_must_match', 'this_must_also_match']],
+            [['1st_of_3_list', '2nd_of_3_list', '3rd_of_3_list']],
+            # Alternative checksums with types
+            [
+                (('adler32', '1st_adler'), ('crc32', '1st_crc')),
+                (('adler32', '2nd_adler'), ('crc32', '2nd_crc'), ('sha1', '2nd_sha')),
+            ],
+            # Entries can be dicts even containing `None`
+            [
+                {
+                    'src-arm.tgz': 'arm_checksum',
+                    'src-x86.tgz': ('mainchecksum', 'altchecksum'),
+                    'src-ppc.tgz': ('mainchecksum', ('md5', 'altchecksum')),
+                    'git-clone.tgz': None,
+                },
+                {
+                    'src': ['checksum_must_match', 'this_must_also_match']
+                },
+                # 2nd required checksum a dict
+                ['first_checksum', {'src-arm': 'arm_checksum'}]
+            ],
         ]
         for checksums in test_inputs:
             self.assertEqual(to_checksums(checksums), checksums)
+        # Also reuse the checksums we use in test_check_type_of_param_value_checksums
+        # When a checksum is valid it must not be modified
+        for checksums in TypeCheckingTest.get_valid_checksums_values():
+            self.assertEqual(to_checksums(checksums), checksums)
+
+        # List in list converted to tuple -> alternatives or checksum with type
+        checksums = [['1stchecksum', ['md5', 'md5sum']]]
+        checksums_expected = [['1stchecksum', ('md5', 'md5sum')]]
+        self.assertEqual(to_checksums(checksums), checksums_expected)
+
+        # Error detection
+        wrong_nesting = [('1stchecksum', ('md5', ('md5sum', 'altmd5sum')))]
+        self.assertErrorRegex(EasyBuildError, 'Unexpected type.*md5', to_checksums, wrong_nesting)
+        correct_nesting = [('1stchecksum', ('md5', 'md5sum'), ('md5', 'altmd5sum'))]
+        self.assertEqual(to_checksums(correct_nesting), correct_nesting)
+        # YEB (YAML EC) doesn't has tuples so it uses lists instead which need to get converted
+        correct_nesting_yeb = [[['1stchecksum', ['md5', 'md5sum'], ['md5', 'altmd5sum']]]]
+        correct_nesting_yeb_conv = [[('1stchecksum', ('md5', 'md5sum'), ('md5', 'altmd5sum'))]]
+        self.assertEqual(to_checksums(correct_nesting_yeb), correct_nesting_yeb_conv)
+        self.assertEqual(to_checksums(correct_nesting_yeb_conv), correct_nesting_yeb_conv)
+
+        unexpected_set = [('1stchecksum', {'md5', 'md5sum'})]
+        self.assertErrorRegex(EasyBuildError, 'Unexpected type.*md5', to_checksums, unexpected_set)
+        unexpected_dict = [{'src': ('md5sum', {'src': 'shasum'})}]
+        self.assertErrorRegex(EasyBuildError, 'Unexpected type.*shasum', to_checksums, unexpected_dict)
+        correct_dict = [{'src': ('md5sum', 'shasum')}]
+        self.assertEqual(to_checksums(correct_dict), correct_dict)
+        correct_dict_1 = [{'src': [['md5', 'md5sum'], ['sha', 'shasum']]}]
+        correct_dict_2 = [{'src': [('md5', 'md5sum'), ('sha', 'shasum')]}]
+        self.assertEqual(to_checksums(correct_dict_2), correct_dict_2)
+        self.assertEqual(to_checksums(correct_dict_1), correct_dict_2)  # inner lists to tuples
+
+        unexpected_Nones = [
+            [('1stchecksum', None)],
+            [['1stchecksum', None]],
+            [{'src': ('md5sum', None)}],
+            [{'src': ['md5sum', None]}],
+        ]
+        self.assertErrorRegex(EasyBuildError, 'Unexpected None', to_checksums, unexpected_Nones[0])
+        self.assertErrorRegex(EasyBuildError, 'Unexpected None', to_checksums, unexpected_Nones[1])
+        self.assertErrorRegex(EasyBuildError, 'Unexpected None', to_checksums, unexpected_Nones[2])
+        self.assertErrorRegex(EasyBuildError, 'Unexpected None', to_checksums, unexpected_Nones[3])
 
     def test_ensure_iterable_license_specs(self):
         """Test ensure_iterable_license_specs function."""