Refactored tests into new tests/ folder

Guided by https://docs.pytest.org/en/latest/goodpractices.html

tests/test_helpers.py

@@ -0,0 +1,117 @@
+"""
+Tests for various datasette helper functions.
+"""
+
+from datasette import app
+import pytest
+import json
+
+
+@pytest.mark.parametrize('path,expected', [
+    ('foo', ['foo']),
+    ('foo,bar', ['foo', 'bar']),
+    ('123,433,112', ['123', '433', '112']),
+    ('123%2C433,112', ['123,433', '112']),
+    ('123%2F433%2F112', ['123/433/112']),
+])
+def test_compound_pks_from_path(path, expected):
+    assert expected == app.compound_pks_from_path(path)
+
+
+@pytest.mark.parametrize('row,pks,expected_path', [
+    ({'A': 'foo', 'B': 'bar'}, ['A', 'B'], 'foo,bar'),
+    ({'A': 'f,o', 'B': 'bar'}, ['A', 'B'], 'f%2Co,bar'),
+    ({'A': 123}, ['A'], '123'),
+])
+def test_path_from_row_pks(row, pks, expected_path):
+    actual_path = app.path_from_row_pks(row, pks, False)
+    assert expected_path == actual_path
+
+
+@pytest.mark.parametrize('obj,expected', [
+    ({
+        'Description': 'Soft drinks',
+        'Picture': b"\x15\x1c\x02\xc7\xad\x05\xfe",
+        'CategoryID': 1,
+    }, """
+        {"CategoryID": 1, "Description": "Soft drinks", "Picture": {"$base64": true, "encoded": "FRwCx60F/g=="}}
+    """.strip()),
+])
+def test_custom_json_encoder(obj, expected):
+    actual = json.dumps(
+        obj,
+        cls=app.CustomJSONEncoder,
+        sort_keys=True
+    )
+    assert expected == actual
+
+
+@pytest.mark.parametrize('args,expected_where,expected_params', [
+    (
+        {
+            'name_english__contains': ['foo'],
+        },
+        '"name_english" like :p0',
+        ['%foo%']
+    ),
+    (
+        {
+            'foo': ['bar'],
+            'bar__contains': ['baz'],
+        },
+        '"bar" like :p0 and "foo" = :p1',
+        ['%baz%', 'bar']
+    ),
+    (
+        {
+            'foo__startswith': ['bar'],
+            'bar__endswith': ['baz'],
+        },
+        '"bar" like :p0 and "foo" like :p1',
+        ['%baz', 'bar%']
+    ),
+    (
+        {
+            'foo__lt': ['1'],
+            'bar__gt': ['2'],
+            'baz__gte': ['3'],
+            'bax__lte': ['4'],
+        },
+        '"bar" > :p0 and "bax" <= :p1 and "baz" >= :p2 and "foo" < :p3',
+        [2, 4, 3, 1]
+    ),
+    (
+        {
+            'foo__like': ['2%2'],
+            'zax__glob': ['3*'],
+        },
+        '"foo" like :p0 and "zax" glob :p1',
+        ['2%2', '3*']
+    ),
+])
+def test_build_where(args, expected_where, expected_params):
+    actual_where, actual_params = app.build_where_clause(args)
+    assert expected_where == actual_where
+    assert {
+        'p{}'.format(i): param
+        for i, param in enumerate(expected_params)
+    } == actual_params
+
+
+@pytest.mark.parametrize('bad_sql', [
+    'update blah;',
+    'PRAGMA case_sensitive_like = true'
+    "SELECT * FROM pragma_index_info('idx52')",
+])
+def test_validate_sql_select_bad(bad_sql):
+    with pytest.raises(app.InvalidSql):
+        app.validate_sql_select(bad_sql)
+
+
+@pytest.mark.parametrize('good_sql', [
+    'select count(*) from airports',
+    'select foo from bar',
+    'select 1 + 1',
+])
+def test_validate_sql_select_good(good_sql):
+    app.validate_sql_select(good_sql)