add_foreign_key can now detect table and pk, refs #25

tests/test_cli.py

@@ -220,7 +220,18 @@ def test_add_column_not_null_default(db_path):
     )
 
 
-def test_add_foreign_key(db_path):
+@pytest.mark.parametrize(
+    "args,assert_message",
+    (
+        (
+            ["books", "author_id", "authors", "id"],
+            "Explicit other_table and other_column",
+        ),
+        (["books", "author_id", "authors"], "Explicit other_table, guess other_column"),
+        (["books", "author_id"], "Automatically guess other_table and other_column"),
+    ),
+)
+def test_add_foreign_key(db_path, args, assert_message):
     db = Database(db_path)
     db["authors"].insert_all(
         [{"id": 1, "name": "Sally"}, {"id": 2, "name": "Asheesh"}], pk="id"
@@ -232,13 +243,8 @@ def test_add_foreign_key(db_path):
         ]
     )
     assert (
-        0
-        == CliRunner()
-        .invoke(
-            cli.cli, ["add-foreign-key", db_path, "books", "author_id", "authors", "id"]
-        )
-        .exit_code
-    )
+        0 == CliRunner().invoke(cli.cli, ["add-foreign-key", db_path] + args).exit_code
+    ), assert_message
     assert [
         ForeignKey(
             table="books", column="author_id", other_table="authors", other_column="id"

tests/test_create.py

@@ -228,6 +228,17 @@ def test_add_column_foreign_key(fresh_db):
     )
 
 
+def test_add_foreign_key_guess_table(fresh_db):
+    fresh_db.create_table("dogs", {"name": str})
+    fresh_db.create_table("breeds", {"name": str, "id": int}, pk="id")
+    fresh_db["dogs"].add_column("breed_id", int)
+    fresh_db["dogs"].add_foreign_key("breed_id")
+    assert (
+        "CREATE TABLE [dogs] ( [name] TEXT , [breed_id] INTEGER, FOREIGN KEY(breed_id) REFERENCES breeds(id) )"
+        == collapse_whitespace(fresh_db["dogs"].schema)
+    )
+
+
 @pytest.mark.parametrize(
     "extra_data,expected_new_columns",
     [

tests/test_introspect.py

@@ -1,4 +1,5 @@
 from sqlite_utils.db import Index
+import pytest
 
 
 def test_table_names(existing_db):
@@ -79,3 +80,19 @@ def test_indexes(fresh_db):
         ),
         Index(seq=1, name="Gosh_c1", unique=0, origin="c", partial=0, columns=["c1"]),
     ] == fresh_db["Gosh"].indexes
+
+
+@pytest.mark.parametrize(
+    "column,expected_table_guess",
+    (
+        ("author", "authors"),
+        ("author_id", "authors"),
+        ("authors", "authors"),
+        ("genre", "genre"),
+        ("genre_id", "genre"),
+    ),
+)
+def test_guess_foreign_table(fresh_db, column, expected_table_guess):
+    fresh_db.create_table("authors", {"name": str})
+    fresh_db.create_table("genre", {"name": str})
+    assert expected_table_guess == fresh_db["books"].guess_foreign_table(column)