Travis CI: basic Python test suite (#156)

.gitignore

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+__pycache__/
+.cache
+.pytest_cache/

.travis.yml

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+language: python
+python:
+  - "3.6"
+cache: pip
+install:
+  - pip install --requirement=tests/requirements.txt
+script:
+  - pytest --verbose tests

tests/requirements.txt

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+jsonref
+jsonschema

tests/test_json.py

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+import json
+import pathlib
+
+import jsonref
+import jsonschema
+
+import pytest
+
+"""
+The following section defines pytest fixtures, which can be used as arguments
+to tests, causing those tests to be run for all fixture values.
+"""
+
+root = pathlib.Path(__file__).parent.parent
+json_paths = list(root.glob('*.json'))
+
+
+@pytest.fixture(params=json_paths, ids=[x.name for x in json_paths])
+def json_path(request):
+    """
+    Paths that correspond to JSON files.
+    """
+    return root.joinpath(request.param)
+
+
+@pytest.fixture(params=[
+    'csl-citation.json',
+    'csl-data.json',
+])
+def json_schema(request):
+    """
+    JSON objects that correspond to JSON schemas.
+    """
+    path = root.joinpath(request.param)
+    text = path.read_text()
+    # Dereference schemas as workaround for https://github.com/Julian/jsonschema/issues/447
+    schema = jsonref.loads(text, jsonschema=True)
+    return schema
+
+
+@pytest.fixture
+def csl_data_validator():
+    text = root.joinpath('csl-data.json').read_text()
+    schema = jsonref.loads(text, jsonschema=True)
+    Validator = jsonschema.validators.validator_for(schema)
+    return Validator(schema)
+
+
+"""
+The following section contains the tests.
+"""
+
+
+def test_read_json(json_path):
+    """
+    Test that a JSON file can be read into Python.
+    """
+    text = json_path.read_text()
+    json.loads(text)
+
+
+def test_schema_property_specified(json_schema):
+    """
+    Test that JSON schemas set the $schema property.
+    https://json-schema.org/understanding-json-schema/reference/schema.html
+    https://github.com/citation-style-language/schema/pull/153
+    """
+    json_schema['$schema']
+
+
+def test_schema_is_valid(json_schema):
+    """
+    Infer the JSON Schema draft from $schema and then check that the input
+    schema is valid.
+    """
+    Validator = jsonschema.validators.validator_for(json_schema)
+    Validator.check_schema(json_schema)
+
+
+def test_basic_data_schema_validates(csl_data_validator):
+    csl = [{
+        'id': 'example-id',
+        'type': 'report',
+    }]
+    csl_data_validator.validate(csl)
+
+
+def test_data_schema_with_extra_property_fails(csl_data_validator):
+    csl = [{
+        'id': 'example-id',
+        'type': 'report',
+        'not-a-csl-key': None,
+    }]
+    with pytest.raises(jsonschema.exceptions.ValidationError):
+        csl_data_validator.validate(csl)