diff --git a/swh/indexer/tests/test_metadata.py b/swh/indexer/tests/test_metadata.py
index 6eb5cbb..2c4a91b 100644
--- a/swh/indexer/tests/test_metadata.py
+++ b/swh/indexer/tests/test_metadata.py
@@ -1,1212 +1,1209 @@
 # Copyright (C) 2017-2018  The Software Heritage developers
 # See the AUTHORS file at the top-level directory of this distribution
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
 import json
 import unittest
 
 from hypothesis import given, strategies, settings, HealthCheck
-from typing import cast
 
 from swh.model.hashutil import hash_to_bytes
 
 from swh.indexer.codemeta import CODEMETA_TERMS, CROSSWALK_TABLE
 from swh.indexer.codemeta import merge_documents
 from swh.indexer.metadata_dictionary import MAPPINGS
 from swh.indexer.metadata_dictionary.base import merge_values
 from swh.indexer.metadata_dictionary.maven import MavenMapping
 from swh.indexer.metadata_dictionary.npm import NpmMapping
 from swh.indexer.metadata_dictionary.ruby import GemspecMapping
 from swh.indexer.metadata_detector import (
     detect_metadata
 )
 from swh.indexer.metadata import (
     ContentMetadataIndexer, RevisionMetadataIndexer
 )
 
 from .utils import (
     BASE_TEST_CONFIG, fill_obj_storage, fill_storage,
     YARN_PARSER_METADATA, json_document_strategy,
     xml_document_strategy,
 )
 
 
 TRANSLATOR_TOOL = {
     'name': 'swh-metadata-translator',
     'version': '0.0.2',
     'configuration': {
         'type': 'local',
         'context': 'NpmMapping'
     }
 }
 
 
 class ContentMetadataTestIndexer(ContentMetadataIndexer):
     """Specific Metadata whose configuration is enough to satisfy the
        indexing tests.
     """
     def parse_config_file(self, *args, **kwargs):
         assert False, 'should not be called; the rev indexer configures it.'
 
 
 REVISION_METADATA_CONFIG = {
     **BASE_TEST_CONFIG,
     'tools': TRANSLATOR_TOOL,
 }
 
 
 class Metadata(unittest.TestCase):
     """
     Tests metadata_mock_tool tool for Metadata detection
     """
     def setUp(self):
         """
         shows the entire diff in the results
         """
         self.maxDiff = None
         self.npm_mapping = MAPPINGS['NpmMapping']()
         self.codemeta_mapping = MAPPINGS['CodemetaMapping']()
         self.maven_mapping = MAPPINGS['MavenMapping']()
         self.pkginfo_mapping = MAPPINGS['PythonPkginfoMapping']()
         self.gemspec_mapping = MAPPINGS['GemspecMapping']()
 
     def test_crosstable(self):
         self.assertEqual(CROSSWALK_TABLE['NodeJS'], {
             'repository': 'http://schema.org/codeRepository',
             'os': 'http://schema.org/operatingSystem',
             'cpu': 'http://schema.org/processorRequirements',
             'engines':
                 'http://schema.org/processorRequirements',
             'author': 'http://schema.org/author',
             'author.email': 'http://schema.org/email',
             'author.name': 'http://schema.org/name',
             'contributor': 'http://schema.org/contributor',
             'keywords': 'http://schema.org/keywords',
             'license': 'http://schema.org/license',
             'version': 'http://schema.org/version',
             'description': 'http://schema.org/description',
             'name': 'http://schema.org/name',
             'bugs': 'https://codemeta.github.io/terms/issueTracker',
             'homepage': 'http://schema.org/url'
         })
 
     def test_merge_values(self):
         self.assertEqual(
             merge_values('a', 'b'),
             ['a', 'b'])
         self.assertEqual(
             merge_values(['a', 'b'], 'c'),
             ['a', 'b', 'c'])
         self.assertEqual(
             merge_values('a', ['b', 'c']),
             ['a', 'b', 'c'])
 
         self.assertEqual(
             merge_values({'@list': ['a']}, {'@list': ['b']}),
             {'@list': ['a', 'b']})
         self.assertEqual(
             merge_values({'@list': ['a', 'b']}, {'@list': ['c']}),
             {'@list': ['a', 'b', 'c']})
 
         with self.assertRaises(ValueError):
             merge_values({'@list': ['a']}, 'b')
         with self.assertRaises(ValueError):
             merge_values('a', {'@list': ['b']})
         with self.assertRaises(ValueError):
             merge_values({'@list': ['a']}, ['b'])
         with self.assertRaises(ValueError):
             merge_values(['a'], {'@list': ['b']})
 
         self.assertEqual(
             merge_values('a', None),
             'a')
         self.assertEqual(
             merge_values(['a', 'b'], None),
             ['a', 'b'])
         self.assertEqual(
             merge_values(None, ['b', 'c']),
             ['b', 'c'])
         self.assertEqual(
             merge_values({'@list': ['a']}, None),
             {'@list': ['a']})
         self.assertEqual(
             merge_values(None, {'@list': ['a']}),
             {'@list': ['a']})
 
     def test_compute_metadata_none(self):
         """
         testing content empty content is empty
         should return None
         """
         # given
         content = b""
 
         # None if no metadata was found or an error occurred
         declared_metadata = None
         # when
         result = self.npm_mapping.translate(content)
         # then
         self.assertEqual(declared_metadata, result)
 
     def test_compute_metadata_npm(self):
         """
         testing only computation of metadata with hard_mapping_npm
         """
         # given
         content = b"""
             {
                 "name": "test_metadata",
                 "version": "0.0.2",
                 "description": "Simple package.json test for indexer",
                   "repository": {
                     "type": "git",
                     "url": "https://github.com/moranegg/metadata_test"
                 },
                 "author": {
                     "email": "moranegg@example.com",
                     "name": "Morane G"
                 }
             }
         """
         declared_metadata = {
             '@context': 'https://doi.org/10.5063/schema/codemeta-2.0',
             'type': 'SoftwareSourceCode',
             'name': 'test_metadata',
             'version': '0.0.2',
             'description': 'Simple package.json test for indexer',
             'codeRepository':
                 'git+https://github.com/moranegg/metadata_test',
             'author': [{
                 'type': 'Person',
                 'name': 'Morane G',
                 'email': 'moranegg@example.com',
             }],
         }
 
         # when
         result = self.npm_mapping.translate(content)
         # then
         self.assertEqual(declared_metadata, result)
 
     def test_merge_documents(self):
         """
         Test the creation of a coherent minimal metadata set
         """
         # given
         metadata_list = [{
             '@context': 'https://doi.org/10.5063/schema/codemeta-2.0',
             'name': 'test_1',
             'version': '0.0.2',
             'description': 'Simple package.json test for indexer',
             'codeRepository':
                 'git+https://github.com/moranegg/metadata_test',
         }, {
             '@context': 'https://doi.org/10.5063/schema/codemeta-2.0',
             'name': 'test_0_1',
             'version': '0.0.2',
             'description': 'Simple package.json test for indexer',
             'codeRepository':
                 'git+https://github.com/moranegg/metadata_test'
         }, {
             '@context': 'https://doi.org/10.5063/schema/codemeta-2.0',
             'name': 'test_metadata',
             'version': '0.0.2',
             'author': 'moranegg',
         }]
 
         # when
         results = merge_documents(metadata_list)
 
         # then
         expected_results = {
             '@context': 'https://doi.org/10.5063/schema/codemeta-2.0',
             "version": '0.0.2',
             "description": 'Simple package.json test for indexer',
             "name": ['test_1', 'test_0_1', 'test_metadata'],
             "author": ['moranegg'],
             "codeRepository":
                 'git+https://github.com/moranegg/metadata_test',
         }
         self.assertEqual(expected_results, results)
 
     def test_index_content_metadata_npm(self):
         """
         testing NPM with package.json
         - one sha1 uses a file that can't be translated to metadata and
           should return None in the translated metadata
         """
         # given
         sha1s = [
             hash_to_bytes('26a9f72a7c87cc9205725cfd879f514ff4f3d8d5'),
             hash_to_bytes('d4c647f0fc257591cc9ba1722484229780d1c607'),
             hash_to_bytes('02fb2c89e14f7fab46701478c83779c7beb7b069'),
         ]
         # this metadata indexer computes only metadata for package.json
         # in npm context with a hard mapping
         config = BASE_TEST_CONFIG.copy()
         config['tools'] = [TRANSLATOR_TOOL]
         metadata_indexer = ContentMetadataTestIndexer(config=config)
         fill_obj_storage(metadata_indexer.objstorage)
         fill_storage(metadata_indexer.storage)
 
         # when
         metadata_indexer.run(sha1s, policy_update='ignore-dups')
         results = list(metadata_indexer.idx_storage.content_metadata_get(
             sha1s))
 
         expected_results = [{
             'metadata': {
                 '@context': 'https://doi.org/10.5063/schema/codemeta-2.0',
                 'type': 'SoftwareSourceCode',
                 'codeRepository':
                     'git+https://github.com/moranegg/metadata_test',
                 'description': 'Simple package.json test for indexer',
                 'name': 'test_metadata',
                 'version': '0.0.1'
             },
             'id': hash_to_bytes('26a9f72a7c87cc9205725cfd879f514ff4f3d8d5'),
             }, {
             'metadata': {
                 '@context': 'https://doi.org/10.5063/schema/codemeta-2.0',
                 'type': 'SoftwareSourceCode',
                 'issueTracker':
                     'https://github.com/npm/npm/issues',
                 'author': [{
                     'type': 'Person',
                     'name': 'Isaac Z. Schlueter',
                     'email': 'i@izs.me',
                     'url': 'http://blog.izs.me',
                 }],
                 'codeRepository':
                     'git+https://github.com/npm/npm',
                 'description': 'a package manager for JavaScript',
                 'license': 'https://spdx.org/licenses/Artistic-2.0',
                 'version': '5.0.3',
                 'name': 'npm',
                 'keywords': [
                     'install',
                     'modules',
                     'package manager',
                     'package.json'
                 ],
                 'url': 'https://docs.npmjs.com/'
             },
             'id': hash_to_bytes('d4c647f0fc257591cc9ba1722484229780d1c607')
         }]
 
         for result in results:
             del result['tool']
 
         # The assertion below returns False sometimes because of nested lists
         self.assertEqual(expected_results, results)
 
     def test_npm_bugs_normalization(self):
         # valid dictionary
         package_json = b"""{
             "name": "foo",
             "bugs": {
                 "url": "https://github.com/owner/project/issues",
                 "email": "foo@example.com"
             }
         }"""
         result = self.npm_mapping.translate(package_json)
         self.assertEqual(result, {
             '@context': 'https://doi.org/10.5063/schema/codemeta-2.0',
             'name': 'foo',
             'issueTracker': 'https://github.com/owner/project/issues',
             'type': 'SoftwareSourceCode',
         })
 
         # "invalid" dictionary
         package_json = b"""{
             "name": "foo",
             "bugs": {
                 "email": "foo@example.com"
             }
         }"""
         result = self.npm_mapping.translate(package_json)
         self.assertEqual(result, {
             '@context': 'https://doi.org/10.5063/schema/codemeta-2.0',
             'name': 'foo',
             'type': 'SoftwareSourceCode',
         })
 
         # string
         package_json = b"""{
             "name": "foo",
             "bugs": "https://github.com/owner/project/issues"
         }"""
         result = self.npm_mapping.translate(package_json)
         self.assertEqual(result, {
             '@context': 'https://doi.org/10.5063/schema/codemeta-2.0',
             'name': 'foo',
             'issueTracker': 'https://github.com/owner/project/issues',
             'type': 'SoftwareSourceCode',
         })
 
     def test_npm_repository_normalization(self):
         # normal
         package_json = b"""{
             "name": "foo",
             "repository": {
                 "type" : "git",
                 "url" : "https://github.com/npm/cli.git"
             }
         }"""
         result = self.npm_mapping.translate(package_json)
         self.assertEqual(result, {
             '@context': 'https://doi.org/10.5063/schema/codemeta-2.0',
             'name': 'foo',
             'codeRepository': 'git+https://github.com/npm/cli.git',
             'type': 'SoftwareSourceCode',
         })
 
         # missing url
         package_json = b"""{
             "name": "foo",
             "repository": {
                 "type" : "git"
             }
         }"""
         result = self.npm_mapping.translate(package_json)
         self.assertEqual(result, {
             '@context': 'https://doi.org/10.5063/schema/codemeta-2.0',
             'name': 'foo',
             'type': 'SoftwareSourceCode',
         })
 
         # github shortcut
         package_json = b"""{
             "name": "foo",
             "repository": "github:npm/cli"
         }"""
         result = self.npm_mapping.translate(package_json)
         expected_result = {
             '@context': 'https://doi.org/10.5063/schema/codemeta-2.0',
             'name': 'foo',
             'codeRepository': 'git+https://github.com/npm/cli.git',
             'type': 'SoftwareSourceCode',
         }
         self.assertEqual(result, expected_result)
 
         # github shortshortcut
         package_json = b"""{
             "name": "foo",
             "repository": "npm/cli"
         }"""
         result = self.npm_mapping.translate(package_json)
         self.assertEqual(result, expected_result)
 
         # gitlab shortcut
         package_json = b"""{
             "name": "foo",
             "repository": "gitlab:user/repo"
         }"""
         result = self.npm_mapping.translate(package_json)
         self.assertEqual(result, {
             '@context': 'https://doi.org/10.5063/schema/codemeta-2.0',
             'name': 'foo',
             'codeRepository': 'git+https://gitlab.com/user/repo.git',
             'type': 'SoftwareSourceCode',
         })
 
     def test_detect_metadata_package_json(self):
         # given
         df = [{
                 'sha1_git': b'abc',
                 'name': b'index.js',
                 'target': b'abc',
                 'length': 897,
                 'status': 'visible',
                 'type': 'file',
                 'perms': 33188,
                 'dir_id': b'dir_a',
                 'sha1': b'bcd'
             },
             {
                 'sha1_git': b'aab',
                 'name': b'package.json',
                 'target': b'aab',
                 'length': 712,
                 'status': 'visible',
                 'type': 'file',
                 'perms': 33188,
                 'dir_id': b'dir_a',
                 'sha1': b'cde'
         }]
         # when
         results = detect_metadata(df)
 
         expected_results = {
             'NpmMapping': [
                 b'cde'
             ]
         }
         # then
         self.assertEqual(expected_results, results)
 
     def test_compute_metadata_valid_codemeta(self):
         raw_content = (
             b"""{
             "@context": "https://doi.org/10.5063/schema/codemeta-2.0",
             "@type": "SoftwareSourceCode",
             "identifier": "CodeMeta",
             "description": "CodeMeta is a concept vocabulary that can be used to standardize the exchange of software metadata across repositories and organizations.",
             "name": "CodeMeta: Minimal metadata schemas for science software and code, in JSON-LD",
             "codeRepository": "https://github.com/codemeta/codemeta",
             "issueTracker": "https://github.com/codemeta/codemeta/issues",
             "license": "https://spdx.org/licenses/Apache-2.0",
             "version": "2.0",
             "author": [
               {
                 "@type": "Person",
                 "givenName": "Carl",
                 "familyName": "Boettiger",
                 "email": "cboettig@gmail.com",
                 "@id": "http://orcid.org/0000-0002-1642-628X"
               },
               {
                 "@type": "Person",
                 "givenName": "Matthew B.",
                 "familyName": "Jones",
                 "email": "jones@nceas.ucsb.edu",
                 "@id": "http://orcid.org/0000-0003-0077-4738"
               }
             ],
             "maintainer": {
               "@type": "Person",
               "givenName": "Carl",
               "familyName": "Boettiger",
               "email": "cboettig@gmail.com",
               "@id": "http://orcid.org/0000-0002-1642-628X"
             },
             "contIntegration": "https://travis-ci.org/codemeta/codemeta",
             "developmentStatus": "active",
             "downloadUrl": "https://github.com/codemeta/codemeta/archive/2.0.zip",
             "funder": {
                 "@id": "https://doi.org/10.13039/100000001",
                 "@type": "Organization",
                 "name": "National Science Foundation"
             },
             "funding":"1549758; Codemeta: A Rosetta Stone for Metadata in Scientific Software",
             "keywords": [
               "metadata",
               "software"
             ],
             "version":"2.0",
             "dateCreated":"2017-06-05",
             "datePublished":"2017-06-05",
             "programmingLanguage": "JSON-LD"
           }""") # noqa
         expected_result = {
             "@context": "https://doi.org/10.5063/schema/codemeta-2.0",
             "type": "SoftwareSourceCode",
             "identifier": "CodeMeta",
             "description":
                 "CodeMeta is a concept vocabulary that can "
                 "be used to standardize the exchange of software metadata "
                 "across repositories and organizations.",
             "name":
                 "CodeMeta: Minimal metadata schemas for science "
                 "software and code, in JSON-LD",
             "codeRepository": "https://github.com/codemeta/codemeta",
             "issueTracker": "https://github.com/codemeta/codemeta/issues",
             "license": "https://spdx.org/licenses/Apache-2.0",
             "version": "2.0",
             "author": [
               {
                 "type": "Person",
                 "givenName": "Carl",
                 "familyName": "Boettiger",
                 "email": "cboettig@gmail.com",
                 "id": "http://orcid.org/0000-0002-1642-628X"
               },
               {
                 "type": "Person",
                 "givenName": "Matthew B.",
                 "familyName": "Jones",
                 "email": "jones@nceas.ucsb.edu",
                 "id": "http://orcid.org/0000-0003-0077-4738"
               }
             ],
             "maintainer": {
               "type": "Person",
               "givenName": "Carl",
               "familyName": "Boettiger",
               "email": "cboettig@gmail.com",
               "id": "http://orcid.org/0000-0002-1642-628X"
             },
             "contIntegration": "https://travis-ci.org/codemeta/codemeta",
             "developmentStatus": "active",
             "downloadUrl":
                 "https://github.com/codemeta/codemeta/archive/2.0.zip",
             "funder": {
                 "id": "https://doi.org/10.13039/100000001",
                 "type": "Organization",
                 "name": "National Science Foundation"
             },
             "funding": "1549758; Codemeta: A Rosetta Stone for Metadata "
                 "in Scientific Software",
             "keywords": [
               "metadata",
               "software"
             ],
             "version": "2.0",
             "dateCreated": "2017-06-05",
             "datePublished": "2017-06-05",
             "programmingLanguage": "JSON-LD"
           }
         result = self.codemeta_mapping.translate(raw_content)
         self.assertEqual(result, expected_result)
 
     def test_compute_metadata_codemeta_alternate_context(self):
         raw_content = (
             b"""{
             "@context": "https://raw.githubusercontent.com/codemeta/codemeta/master/codemeta.jsonld",
             "@type": "SoftwareSourceCode",
             "identifier": "CodeMeta"
         }""")  # noqa
         expected_result = {
             "@context": "https://doi.org/10.5063/schema/codemeta-2.0",
             "type": "SoftwareSourceCode",
             "identifier": "CodeMeta",
         }
         result = self.codemeta_mapping.translate(raw_content)
         self.assertEqual(result, expected_result)
 
     def test_compute_metadata_maven(self):
         raw_content = b"""
         <project>
           <name>Maven Default Project</name>
           <modelVersion>4.0.0</modelVersion>
           <groupId>com.mycompany.app</groupId>
           <artifactId>my-app</artifactId>
           <version>1.2.3</version>
           <repositories>
             <repository>
               <id>central</id>
               <name>Maven Repository Switchboard</name>
               <layout>default</layout>
               <url>http://repo1.maven.org/maven2</url>
               <snapshots>
                 <enabled>false</enabled>
               </snapshots>
             </repository>
           </repositories>
           <licenses>
             <license>
               <name>Apache License, Version 2.0</name>
               <url>https://www.apache.org/licenses/LICENSE-2.0.txt</url>
               <distribution>repo</distribution>
               <comments>A business-friendly OSS license</comments>
             </license>
           </licenses>
         </project>"""
         result = self.maven_mapping.translate(raw_content)
         self.assertEqual(result, {
             '@context': 'https://doi.org/10.5063/schema/codemeta-2.0',
             'type': 'SoftwareSourceCode',
             'name': 'Maven Default Project',
             'identifier': 'com.mycompany.app',
             'version': '1.2.3',
             'license': 'https://www.apache.org/licenses/LICENSE-2.0.txt',
             'codeRepository':
                 'http://repo1.maven.org/maven2/com/mycompany/app/my-app',
         })
 
     def test_compute_metadata_maven_empty(self):
         raw_content = b"""
         <project>
         </project>"""
         result = self.maven_mapping.translate(raw_content)
         self.assertEqual(result, {
             '@context': 'https://doi.org/10.5063/schema/codemeta-2.0',
             'type': 'SoftwareSourceCode',
         })
 
     def test_compute_metadata_maven_almost_empty(self):
         raw_content = b"""
         <project>
           <foo/>
         </project>"""
         result = self.maven_mapping.translate(raw_content)
         self.assertEqual(result, {
             '@context': 'https://doi.org/10.5063/schema/codemeta-2.0',
             'type': 'SoftwareSourceCode',
         })
 
     def test_compute_metadata_maven_invalid_xml(self):
         expected_warning = (
             'WARNING:swh.indexer.metadata_dictionary.maven.MavenMapping:'
             'Error parsing XML from foo')
 
         raw_content = b"""
         <project>"""
         with self.assertLogs('swh.indexer.metadata_dictionary',
                              level='WARNING') as cm:
             result = MAPPINGS["MavenMapping"]('foo').translate(raw_content)
             self.assertEqual(cm.output, [expected_warning])
         self.assertEqual(result, None)
 
         raw_content = b"""
         """
         with self.assertLogs('swh.indexer.metadata_dictionary',
                              level='WARNING') as cm:
             result = MAPPINGS["MavenMapping"]('foo').translate(raw_content)
             self.assertEqual(cm.output, [expected_warning])
         self.assertEqual(result, None)
 
     def test_compute_metadata_maven_unknown_encoding(self):
         expected_warning = (
             'WARNING:swh.indexer.metadata_dictionary.maven.MavenMapping:'
             'Error detecting XML encoding from foo')
 
         raw_content = b"""<?xml version="1.0" encoding="foo"?>
         <project>
         </project>"""
         with self.assertLogs('swh.indexer.metadata_dictionary',
                              level='WARNING') as cm:
             result = MAPPINGS["MavenMapping"]('foo').translate(raw_content)
             self.assertEqual(cm.output, [expected_warning])
         self.assertEqual(result, None)
 
         raw_content = b"""<?xml version="1.0" encoding="UTF-7"?>
         <project>
         </project>"""
         with self.assertLogs('swh.indexer.metadata_dictionary',
                              level='WARNING') as cm:
             result = MAPPINGS["MavenMapping"]('foo').translate(raw_content)
             self.assertEqual(cm.output, [expected_warning])
         self.assertEqual(result, None)
 
     def test_compute_metadata_maven_invalid_encoding(self):
         expected_warning = (
             'WARNING:swh.indexer.metadata_dictionary.maven.MavenMapping:'
             'Error unidecoding XML from foo')
 
         raw_content = b"""<?xml version="1.0" encoding="UTF-8"?>
         <foo\xe5ct>
         </foo>"""
         with self.assertLogs('swh.indexer.metadata_dictionary',
                              level='WARNING') as cm:
             result = MAPPINGS["MavenMapping"]('foo').translate(raw_content)
             self.assertEqual(cm.output, [expected_warning])
         self.assertEqual(result, None)
 
     def test_compute_metadata_maven_minimal(self):
         raw_content = b"""
         <project>
           <name>Maven Default Project</name>
           <modelVersion>4.0.0</modelVersion>
           <groupId>com.mycompany.app</groupId>
           <artifactId>my-app</artifactId>
           <version>1.2.3</version>
         </project>"""
         result = self.maven_mapping.translate(raw_content)
         self.assertEqual(result, {
             '@context': 'https://doi.org/10.5063/schema/codemeta-2.0',
             'type': 'SoftwareSourceCode',
             'name': 'Maven Default Project',
             'identifier': 'com.mycompany.app',
             'version': '1.2.3',
             'codeRepository':
             'https://repo.maven.apache.org/maven2/com/mycompany/app/my-app',
         })
 
     def test_compute_metadata_maven_empty_nodes(self):
         raw_content = b"""
         <project>
           <name>Maven Default Project</name>
           <modelVersion>4.0.0</modelVersion>
           <groupId>com.mycompany.app</groupId>
           <artifactId>my-app</artifactId>
           <version>1.2.3</version>
           <repositories>
           </repositories>
         </project>"""
         result = self.maven_mapping.translate(raw_content)
         self.assertEqual(result, {
             '@context': 'https://doi.org/10.5063/schema/codemeta-2.0',
             'type': 'SoftwareSourceCode',
             'name': 'Maven Default Project',
             'identifier': 'com.mycompany.app',
             'version': '1.2.3',
             'codeRepository':
             'https://repo.maven.apache.org/maven2/com/mycompany/app/my-app',
         })
 
         raw_content = b"""
         <project>
           <name>Maven Default Project</name>
           <modelVersion>4.0.0</modelVersion>
           <groupId>com.mycompany.app</groupId>
           <artifactId>my-app</artifactId>
           <version></version>
         </project>"""
         result = self.maven_mapping.translate(raw_content)
         self.assertEqual(result, {
             '@context': 'https://doi.org/10.5063/schema/codemeta-2.0',
             'type': 'SoftwareSourceCode',
             'name': 'Maven Default Project',
             'identifier': 'com.mycompany.app',
             'codeRepository':
             'https://repo.maven.apache.org/maven2/com/mycompany/app/my-app',
         })
 
         raw_content = b"""
         <project>
           <name></name>
           <modelVersion>4.0.0</modelVersion>
           <groupId>com.mycompany.app</groupId>
           <artifactId>my-app</artifactId>
           <version>1.2.3</version>
         </project>"""
         result = self.maven_mapping.translate(raw_content)
         self.assertEqual(result, {
             '@context': 'https://doi.org/10.5063/schema/codemeta-2.0',
             'type': 'SoftwareSourceCode',
             'identifier': 'com.mycompany.app',
             'version': '1.2.3',
             'codeRepository':
             'https://repo.maven.apache.org/maven2/com/mycompany/app/my-app',
         })
 
         raw_content = b"""
         <project>
           <name>Maven Default Project</name>
           <modelVersion>4.0.0</modelVersion>
           <groupId>com.mycompany.app</groupId>
           <artifactId>my-app</artifactId>
           <version>1.2.3</version>
           <licenses>
           </licenses>
         </project>"""
         result = self.maven_mapping.translate(raw_content)
         self.assertEqual(result, {
             '@context': 'https://doi.org/10.5063/schema/codemeta-2.0',
             'type': 'SoftwareSourceCode',
             'name': 'Maven Default Project',
             'identifier': 'com.mycompany.app',
             'version': '1.2.3',
             'codeRepository':
             'https://repo.maven.apache.org/maven2/com/mycompany/app/my-app',
         })
 
         raw_content = b"""
         <project>
           <groupId></groupId>
           <version>1.2.3</version>
         </project>"""
         result = self.maven_mapping.translate(raw_content)
         self.assertEqual(result, {
             '@context': 'https://doi.org/10.5063/schema/codemeta-2.0',
             'type': 'SoftwareSourceCode',
             'version': '1.2.3',
         })
 
     def test_compute_metadata_maven_invalid_licenses(self):
         raw_content = b"""
         <project>
           <name>Maven Default Project</name>
           <modelVersion>4.0.0</modelVersion>
           <groupId>com.mycompany.app</groupId>
           <artifactId>my-app</artifactId>
           <version>1.2.3</version>
           <licenses>
             foo
           </licenses>
         </project>"""
         result = self.maven_mapping.translate(raw_content)
         self.assertEqual(result, {
             '@context': 'https://doi.org/10.5063/schema/codemeta-2.0',
             'type': 'SoftwareSourceCode',
             'name': 'Maven Default Project',
             'identifier': 'com.mycompany.app',
             'version': '1.2.3',
             'codeRepository':
             'https://repo.maven.apache.org/maven2/com/mycompany/app/my-app',
         })
 
     def test_compute_metadata_maven_multiple(self):
         '''Tests when there are multiple code repos and licenses.'''
         raw_content = b"""
         <project>
           <name>Maven Default Project</name>
           <modelVersion>4.0.0</modelVersion>
           <groupId>com.mycompany.app</groupId>
           <artifactId>my-app</artifactId>
           <version>1.2.3</version>
           <repositories>
             <repository>
               <id>central</id>
               <name>Maven Repository Switchboard</name>
               <layout>default</layout>
               <url>http://repo1.maven.org/maven2</url>
               <snapshots>
                 <enabled>false</enabled>
               </snapshots>
             </repository>
             <repository>
               <id>example</id>
               <name>Example Maven Repo</name>
               <layout>default</layout>
               <url>http://example.org/maven2</url>
             </repository>
           </repositories>
           <licenses>
             <license>
               <name>Apache License, Version 2.0</name>
               <url>https://www.apache.org/licenses/LICENSE-2.0.txt</url>
               <distribution>repo</distribution>
               <comments>A business-friendly OSS license</comments>
             </license>
             <license>
               <name>MIT license</name>
               <url>https://opensource.org/licenses/MIT</url>
             </license>
           </licenses>
         </project>"""
         result = self.maven_mapping.translate(raw_content)
         self.assertEqual(result, {
             '@context': 'https://doi.org/10.5063/schema/codemeta-2.0',
             'type': 'SoftwareSourceCode',
             'name': 'Maven Default Project',
             'identifier': 'com.mycompany.app',
             'version': '1.2.3',
             'license': [
                 'https://www.apache.org/licenses/LICENSE-2.0.txt',
                 'https://opensource.org/licenses/MIT',
             ],
             'codeRepository': [
                 'http://repo1.maven.org/maven2/com/mycompany/app/my-app',
                 'http://example.org/maven2/com/mycompany/app/my-app',
             ]
         })
 
     def test_compute_metadata_pkginfo(self):
         raw_content = (b"""\
 Metadata-Version: 2.1
 Name: swh.core
 Version: 0.0.49
 Summary: Software Heritage core utilities
 Home-page: https://forge.softwareheritage.org/diffusion/DCORE/
 Author: Software Heritage developers
 Author-email: swh-devel@inria.fr
 License: UNKNOWN
 Project-URL: Bug Reports, https://forge.softwareheritage.org/maniphest
 Project-URL: Funding, https://www.softwareheritage.org/donate
 Project-URL: Source, https://forge.softwareheritage.org/source/swh-core
 Description: swh-core
         ========
        \x20
         core library for swh's modules:
         - config parser
         - hash computations
         - serialization
         - logging mechanism
        \x20
 Platform: UNKNOWN
 Classifier: Programming Language :: Python :: 3
 Classifier: Intended Audience :: Developers
 Classifier: License :: OSI Approved :: GNU General Public License v3 (GPLv3)
 Classifier: Operating System :: OS Independent
 Classifier: Development Status :: 5 - Production/Stable
 Description-Content-Type: text/markdown
 Provides-Extra: testing
 """) # noqa
         result = self.pkginfo_mapping.translate(raw_content)
         self.assertCountEqual(result['description'], [
             'Software Heritage core utilities',  # note the comma here
             'swh-core\n'
             '========\n'
             '\n'
             "core library for swh's modules:\n"
             '- config parser\n'
             '- hash computations\n'
             '- serialization\n'
             '- logging mechanism\n'
             ''],
             result)
         del result['description']
         self.assertEqual(result, {
             '@context': 'https://doi.org/10.5063/schema/codemeta-2.0',
             'type': 'SoftwareSourceCode',
             'url': 'https://forge.softwareheritage.org/diffusion/DCORE/',
             'name': 'swh.core',
             'author': [{
                 'type': 'Person',
                 'name': 'Software Heritage developers',
                 'email': 'swh-devel@inria.fr',
             }],
             'version': '0.0.49',
         })
 
     def test_compute_metadata_pkginfo_utf8(self):
         raw_content = (b'''\
 Metadata-Version: 1.1
 Name: snowpyt
 Description-Content-Type: UNKNOWN
 Description: foo
         Hydrology N\xc2\xb083
 ''') # noqa
         result = self.pkginfo_mapping.translate(raw_content)
         self.assertEqual(result, {
             '@context': 'https://doi.org/10.5063/schema/codemeta-2.0',
             'type': 'SoftwareSourceCode',
             'name': 'snowpyt',
             'description': 'foo\nHydrology N°83',
         })
 
     def test_compute_metadata_pkginfo_keywords(self):
         raw_content = (b"""\
 Metadata-Version: 2.1
 Name: foo
 Keywords: foo bar baz
 """) # noqa
         result = self.pkginfo_mapping.translate(raw_content)
         self.assertEqual(result, {
             '@context': 'https://doi.org/10.5063/schema/codemeta-2.0',
             'type': 'SoftwareSourceCode',
             'name': 'foo',
             'keywords': ['foo', 'bar', 'baz'],
         })
 
     def test_compute_metadata_pkginfo_license(self):
         raw_content = (b"""\
 Metadata-Version: 2.1
 Name: foo
 License: MIT
 """) # noqa
         result = self.pkginfo_mapping.translate(raw_content)
         self.assertEqual(result, {
             '@context': 'https://doi.org/10.5063/schema/codemeta-2.0',
             'type': 'SoftwareSourceCode',
             'name': 'foo',
             'license': 'MIT',
         })
 
     def test_gemspec_base(self):
         raw_content = b"""
 Gem::Specification.new do |s|
   s.name        = 'example'
   s.version     = '0.1.0'
   s.licenses    = ['MIT']
   s.summary     = "This is an example!"
   s.description = "Much longer explanation of the example!"
   s.authors     = ["Ruby Coder"]
   s.email       = 'rubycoder@example.com'
   s.files       = ["lib/example.rb"]
   s.homepage    = 'https://rubygems.org/gems/example'
   s.metadata    = { "source_code_uri" => "https://github.com/example/example" }
 end"""
         result = self.gemspec_mapping.translate(raw_content)
         self.assertCountEqual(result.pop('description'), [
             "This is an example!",
             "Much longer explanation of the example!"
         ])
         self.assertEqual(result, {
             '@context': 'https://doi.org/10.5063/schema/codemeta-2.0',
             'type': 'SoftwareSourceCode',
             'author': ['Ruby Coder'],
             'name': 'example',
             'license': 'https://spdx.org/licenses/MIT',
             'codeRepository': 'https://rubygems.org/gems/example',
             'email': 'rubycoder@example.com',
             'version': '0.1.0',
         })
 
     def test_gemspec_two_author_fields(self):
         raw_content = b"""
 Gem::Specification.new do |s|
   s.authors     = ["Ruby Coder1"]
   s.author      = "Ruby Coder2"
 end"""
         result = self.gemspec_mapping.translate(raw_content)
         self.assertCountEqual(result.pop('author'), [
             'Ruby Coder1', 'Ruby Coder2'])
         self.assertEqual(result, {
             '@context': 'https://doi.org/10.5063/schema/codemeta-2.0',
             'type': 'SoftwareSourceCode',
         })
 
     def test_gemspec_invalid_author(self):
         raw_content = b"""
 Gem::Specification.new do |s|
   s.author      = ["Ruby Coder"]
 end"""
         result = self.gemspec_mapping.translate(raw_content)
         self.assertEqual(result, {
             '@context': 'https://doi.org/10.5063/schema/codemeta-2.0',
             'type': 'SoftwareSourceCode',
         })
         raw_content = b"""
 Gem::Specification.new do |s|
   s.author      = "Ruby Coder1",
 end"""
         result = self.gemspec_mapping.translate(raw_content)
         self.assertEqual(result, {
             '@context': 'https://doi.org/10.5063/schema/codemeta-2.0',
             'type': 'SoftwareSourceCode',
         })
         raw_content = b"""
 Gem::Specification.new do |s|
   s.authors     = ["Ruby Coder1", ["Ruby Coder2"]]
 end"""
         result = self.gemspec_mapping.translate(raw_content)
         self.assertEqual(result, {
             '@context': 'https://doi.org/10.5063/schema/codemeta-2.0',
             'type': 'SoftwareSourceCode',
             'author': ['Ruby Coder1'],
         })
 
     def test_gemspec_alternative_header(self):
         raw_content = b"""
 require './lib/version'
 
 Gem::Specification.new { |s|
   s.name = 'rb-system-with-aliases'
   s.summary = 'execute system commands with aliases'
 }
 """
         result = self.gemspec_mapping.translate(raw_content)
         self.assertEqual(result, {
             '@context': 'https://doi.org/10.5063/schema/codemeta-2.0',
             'type': 'SoftwareSourceCode',
             'name': 'rb-system-with-aliases',
             'description': 'execute system commands with aliases',
         })
 
     @settings(suppress_health_check=[HealthCheck.too_slow])
-    @given(json_document_strategy(
-        keys=list(cast(NpmMapping, MAPPINGS['NpmMapping']).mapping)))
+    @given(json_document_strategy(keys=list(NpmMapping.mapping)))
     def test_npm_adversarial(self, doc):
         raw = json.dumps(doc).encode()
         self.npm_mapping.translate(raw)
 
     @settings(suppress_health_check=[HealthCheck.too_slow])
     @given(json_document_strategy(keys=CODEMETA_TERMS))
     def test_codemeta_adversarial(self, doc):
         raw = json.dumps(doc).encode()
         self.codemeta_mapping.translate(raw)
 
     @settings(suppress_health_check=[HealthCheck.too_slow])
     @given(xml_document_strategy(
-        keys=list(cast(MavenMapping, MAPPINGS['MavenMapping']).mapping),
+        keys=list(MavenMapping.mapping),
         root='project',
         xmlns='http://maven.apache.org/POM/4.0.0'))
     def test_maven_adversarial(self, doc):
         self.maven_mapping.translate(doc)
 
     @settings(suppress_health_check=[HealthCheck.too_slow])
     @given(strategies.dictionaries(
         # keys
         strategies.one_of(
             strategies.text(),
-            *map(strategies.just,
-                 cast(GemspecMapping, MAPPINGS['GemspecMapping']).mapping)
+            *map(strategies.just, GemspecMapping.mapping)
         ),
         # values
         strategies.recursive(
             strategies.characters(),
             lambda children: strategies.lists(children, 1)
         )
     ))
     def test_gemspec_adversarial(self, doc):
         parts = [b'Gem::Specification.new do |s|\n']
         for (k, v) in doc.items():
             parts.append('  s.{} = {}\n'.format(k, repr(v)).encode())
         parts.append(b'end\n')
         self.gemspec_mapping.translate(b''.join(parts))
 
     def test_revision_metadata_indexer(self):
         metadata_indexer = RevisionMetadataIndexer(
             config=REVISION_METADATA_CONFIG)
         fill_obj_storage(metadata_indexer.objstorage)
         fill_storage(metadata_indexer.storage)
 
         tool = metadata_indexer.idx_storage.indexer_configuration_get(
             {'tool_'+k: v for (k, v) in TRANSLATOR_TOOL.items()})
         assert tool is not None
 
         metadata_indexer.idx_storage.content_metadata_add([{
             'indexer_configuration_id': tool['id'],
             'id': b'cde',
             'metadata': YARN_PARSER_METADATA,
         }])
 
         sha1_gits = [
             hash_to_bytes('8dbb6aeb036e7fd80664eb8bfd1507881af1ba9f'),
         ]
         metadata_indexer.run(sha1_gits, 'update-dups')
 
         results = list(
             metadata_indexer.idx_storage.
             revision_intrinsic_metadata_get(sha1_gits))
 
         expected_results = [{
             'id': hash_to_bytes('8dbb6aeb036e7fd80664eb8bfd1507881af1ba9f'),
             'tool': TRANSLATOR_TOOL,
             'metadata': YARN_PARSER_METADATA,
             'mappings': ['npm'],
         }]
 
         for result in results:
             del result['tool']['id']
 
         # then
         self.assertEqual(expected_results, results)
 
     def test_revision_metadata_indexer_single_root_dir(self):
         metadata_indexer = RevisionMetadataIndexer(
             config=REVISION_METADATA_CONFIG)
         fill_obj_storage(metadata_indexer.objstorage)
         fill_storage(metadata_indexer.storage)
 
         # Add a parent directory, that is the only directory at the root
         # of the revision
         rev_id = hash_to_bytes('8dbb6aeb036e7fd80664eb8bfd1507881af1ba9f')
         rev = metadata_indexer.storage._revisions[rev_id]
         subdir_id = rev.directory
         rev.directory = b'123456'
         metadata_indexer.storage.directory_add([{
             'id': b'123456',
             'entries': [{
                 'name': b'foobar-1.0.0',
                 'type': 'dir',
                 'target': subdir_id,
                 'perms': 16384,
             }],
         }])
 
         tool = metadata_indexer.idx_storage.indexer_configuration_get(
             {'tool_'+k: v for (k, v) in TRANSLATOR_TOOL.items()})
         assert tool is not None
 
         metadata_indexer.idx_storage.content_metadata_add([{
             'indexer_configuration_id': tool['id'],
             'id': b'cde',
             'metadata': YARN_PARSER_METADATA,
         }])
 
         sha1_gits = [
             hash_to_bytes('8dbb6aeb036e7fd80664eb8bfd1507881af1ba9f'),
         ]
         metadata_indexer.run(sha1_gits, 'update-dups')
 
         results = list(
             metadata_indexer.idx_storage.
             revision_intrinsic_metadata_get(sha1_gits))
 
         expected_results = [{
             'id': hash_to_bytes('8dbb6aeb036e7fd80664eb8bfd1507881af1ba9f'),
             'tool': TRANSLATOR_TOOL,
             'metadata': YARN_PARSER_METADATA,
             'mappings': ['npm'],
         }]
 
         for result in results:
             del result['tool']['id']
 
         # then
         self.assertEqual(expected_results, results)