Support other unique constraint error format (#115)

Unique constraints sometimes fail with the following error format:

    UNIQUE constraint failed: index '<index_name>'

I believe this happens when the index name doesn't match
the names of the columns involved.

Example of an index for which this happens:

    CREATE UNIQUE INDEX test_user_id_number_year_index
    ON invoices (user_id, number, strftime('%Y', created_at));

Author: reisub

lib/ecto/adapters/sqlite3/connection.ex

@@ -130,6 +130,13 @@ defmodule Ecto.Adapters.SQLite3.Connection do
   end
 
   @impl true
+  def to_constraints(
+        %Exqlite.Error{message: "UNIQUE constraint failed: index " <> constraint},
+        _opts
+      ) do
+    [unique: String.trim(constraint, ~s('))]
+  end
+
   def to_constraints(
         %Exqlite.Error{message: "UNIQUE constraint failed: " <> constraint},
         _opts

test/ecto/adapters/sqlite3/connection_test.exs

@@ -2414,6 +2414,40 @@ defmodule Ecto.Adapters.SQLite3.ConnectionTest do
     assert execute_ddl(integer) == [~s/CREATE TABLE "posts" ("id" INTEGER PRIMARY KEY)/]
   end
 
+  describe "to_constraints/2" do
+    alias Ecto.Adapters.SQLite3.Connection
+
+    test "unique index" do
+      # created with:
+      # CREATE UNIQUE INDEX users_email_name_index ON users (email);
+
+      error = %Exqlite.Error{message: "UNIQUE constraint failed: users.email"}
+      assert Connection.to_constraints(error, []) == [unique: "users_email_index"]
+    end
+
+    test "multi-column unique index" do
+      # created with:
+      # CREATE UNIQUE INDEX users_email_name_index ON users (email, name);
+
+      error = %Exqlite.Error{
+        message: "UNIQUE constraint failed: users.email, users.name"
+      }
+
+      assert Connection.to_constraints(error, []) == [unique: "users_email_name_index"]
+    end
+
+    test "complex unique index" do
+      # created with:
+      # CREATE UNIQUE INDEX users_email_year_index ON users (email, strftime('%Y', inserted_at));
+
+      error = %Exqlite.Error{
+        message: "UNIQUE constraint failed: index 'users_email_year_index'"
+      }
+
+      assert Connection.to_constraints(error, []) == [unique: "users_email_year_index"]
+    end
+  end
+
   defp remove_newlines(string) do
     string |> String.trim() |> String.replace("\n", " ")
   end