chore: import upstream snapshot with attribution

testing/postgres-client-tests/elixir/lib/postgrex_test.ex

@@ -0,0 +1,47 @@
+defmodule PostgrexTest do
+  def main(args) do
+    [user, port_str] = args
+    port = String.to_integer(port_str)
+
+    {:ok, _} = Application.ensure_all_started(:postgrex)
+
+    {:ok, conn} = Postgrex.start_link(
+      hostname: "localhost",
+      port: port,
+      database: "postgres",
+      username: user,
+      password: "password",
+      ssl: false
+    )
+
+    {:ok, %{rows: [[pk]]}} = Postgrex.query(conn, "SELECT pk FROM test_table LIMIT 1", [])
+    if pk != 1, do: raise("expected pk=1, got #{pk}")
+
+    {:ok, _} = Postgrex.query(conn, "INSERT INTO test_table VALUES (2)", [])
+
+    {:ok, %{rows: [[count]]}} = Postgrex.query(conn, "SELECT COUNT(*) FROM test_table", [])
+    if count != 2, do: raise("expected count=2, got #{count}")
+
+    # Dolt workflow: create table, insert, commit, branch, insert, commit, merge
+    Enum.each([
+      "DROP TABLE IF EXISTS test",
+      "CREATE TABLE test (pk int, value int, PRIMARY KEY(pk))",
+      "INSERT INTO test (pk, value) VALUES (0, 0)",
+      "SELECT dolt_add('-A')",
+      "SELECT dolt_commit('-m', 'added table test')",
+      "SELECT dolt_checkout('-b', 'mybranch')",
+      "INSERT INTO test VALUES (1, 1)",
+      "SELECT dolt_commit('-a', '-m', 'updated test')",
+      "SELECT dolt_checkout('main')",
+      "SELECT dolt_merge('mybranch')"
+    ], fn q -> {:ok, _} = Postgrex.query(conn, q, []) end)
+
+    {:ok, %{rows: [[log_count]]}} = Postgrex.query(conn, "SELECT COUNT(*) FROM dolt_log", [])
+    if log_count != 4, do: raise("expected 4 dolt_log entries, got #{log_count}")
+
+    {:ok, %{rows: [[test_count]]}} = Postgrex.query(conn, "SELECT COUNT(*) FROM test", [])
+    if test_count != 2, do: raise("expected 2 rows in test, got #{test_count}")
+
+    IO.puts("Postgrex test passed")
+  end
+end

testing/postgres-client-tests/elixir/mix.exs

@@ -0,0 +1,21 @@
+defmodule PostgrexTest.MixProject do
+  use Mix.Project
+
+  def project do
+    [
+      app: :postgrex_test,
+      version: "0.1.0",
+      elixir: "~> 1.14",
+      escript: [main_module: PostgrexTest, name: "postgrex-test"],
+      deps: deps()
+    ]
+  end
+
+  def application do
+    [extra_applications: [:logger]]
+  end
+
+  defp deps do
+    [{:postgrex, "~> 0.18"}]
+  end
+end