Added unit tests for inspect() foreign key detection

Used them to fix a bug with it.

Refs #85

datasette/utils.py

@@ -215,7 +215,7 @@ def get_all_foreign_keys(conn):
     for table in tables:
         infos = conn.execute(
             'PRAGMA foreign_key_list([{}])'.format(table)
-        ).fetchmany()
+        ).fetchall()
         for info in infos:
             if info is not None:
                 id, seq, table_name, from_, to_, on_update, on_delete, match = info

tests/test_inspect.py

@@ -0,0 +1,76 @@
+from datasette.app import Datasette
+import os
+import pytest
+import sqlite3
+import tempfile
+
+
+TABLES = '''
+CREATE TABLE "election_results" (
+  "county" INTEGER,
+  "party" INTEGER,
+  "office" INTEGER,
+  "votes" INTEGER,
+  FOREIGN KEY (county) REFERENCES county(id),
+  FOREIGN KEY (party) REFERENCES party(id),
+  FOREIGN KEY (office) REFERENCES office(id)
+ );
+
+CREATE TABLE "county" (
+  "id" INTEGER PRIMARY KEY ,
+  "name" TEXT
+);
+
+CREATE TABLE "party" (
+  "id" INTEGER PRIMARY KEY ,
+  "name" TEXT
+);
+
+CREATE TABLE "office" (
+  "id" INTEGER PRIMARY KEY ,
+  "name" TEXT
+);
+'''
+
+
+@pytest.fixture(scope='module')
+def ds_instance():
+    with tempfile.TemporaryDirectory() as tmpdir:
+        filepath = os.path.join(tmpdir, 'test_tables.db')
+        conn = sqlite3.connect(filepath)
+        conn.executescript(TABLES)
+        yield Datasette([filepath])
+
+
+def test_inspect(ds_instance):
+    info = ds_instance.inspect()
+    tables = info['test_tables']['tables']
+    for table_name in ('county', 'party', 'office'):
+        assert 0 == tables[table_name]['count']
+        foreign_keys = tables[table_name]['foreign_keys']
+        assert [] == foreign_keys['outgoing']
+        assert [{
+            'column': 'id',
+            'other_column': table_name,
+            'other_table': 'election_results'
+        }] == foreign_keys['incoming']
+
+    election_results = tables['election_results']
+    assert 0 == election_results['count']
+    assert sorted([{
+        'column': 'county',
+        'other_column': 'id',
+        'other_table': 'county'
+    }, {
+        'column': 'party',
+        'other_column': 'id',
+        'other_table': 'party'
+    }, {
+        'column': 'office',
+        'other_column': 'id',
+        'other_table': 'office'
+    }], key=lambda d: d['column']) == sorted(
+        election_results['foreign_keys']['outgoing'],
+        key=lambda d: d['column']
+    )
+    assert [] == election_results['foreign_keys']['incoming']