Add ssh integration test

Author: richard-ash

test/examples/ssh_usage_test.exs

@@ -0,0 +1,81 @@
+defmodule MyApp.SSH do
+  @moduledoc false
+
+  # A minimal SSH client — the kind of module a library consumer would write
+  # and want to test against TestServer.SSH.
+  def run(host, port, command, opts \\ []) do
+    user = Keyword.get(opts, :user, "deploy")
+    password = Keyword.get(opts, :password)
+
+    connect_opts =
+      [
+        user: String.to_charlist(user),
+        silently_accept_hosts: true,
+        user_interaction: false,
+        save_accepted_host: false
+      ]
+      |> then(fn o ->
+        if password, do: Keyword.put(o, :password, String.to_charlist(password)), else: o
+      end)
+
+    with {:ok, conn} <- :ssh.connect(String.to_charlist(host), port, connect_opts) do
+      {:ok, ch} = :ssh_connection.session_channel(conn, :infinity)
+      :success = :ssh_connection.exec(conn, ch, String.to_charlist(command), :infinity)
+      result = collect(ch, {0, "", ""})
+      :ssh.close(conn)
+      result
+    end
+  end
+
+  defp collect(ch, {code, out, err}) do
+    receive do
+      {:ssh_cm, _, {:data, ^ch, 0, data}} -> collect(ch, {code, out <> data, err})
+      {:ssh_cm, _, {:data, ^ch, 1, data}} -> collect(ch, {code, out, err <> data})
+      {:ssh_cm, _, {:exit_status, ^ch, c}} -> collect(ch, {c, out, err})
+      {:ssh_cm, _, {:closed, ^ch}} -> {:ok, code, out, err}
+    after
+      5_000 -> {:error, :timeout}
+    end
+  end
+end
+
+defmodule MyApp.SSHUsageTest do
+  use ExUnit.Case
+
+  # Demonstrates the intended public API of TestServer.SSH from a consumer's perspective.
+
+  test "runs a remote command and returns output" do
+    TestServer.SSH.exec(to: fn "deploy", state -> {:reply, {0, "deployed v1.0\n", ""}, state} end)
+    {host, port} = TestServer.SSH.address()
+    assert {:ok, 0, "deployed v1.0\n", ""} = MyApp.SSH.run(host, port, "deploy")
+  end
+
+  test "propagates non-zero exit codes" do
+    TestServer.SSH.exec(to: fn _, state -> {:reply, {1, "", "permission denied\n"}, state} end)
+    {host, port} = TestServer.SSH.address()
+    assert {:ok, 1, "", "permission denied\n"} = MyApp.SSH.run(host, port, "restricted")
+  end
+
+  test "sequential deploys consume handlers in FIFO order" do
+    TestServer.SSH.exec(to: fn _, state -> {:reply, {0, "deploy 1\n", ""}, state} end)
+    TestServer.SSH.exec(to: fn _, state -> {:reply, {0, "deploy 2\n", ""}, state} end)
+    {host, port} = TestServer.SSH.address()
+    assert {:ok, 0, "deploy 1\n", ""} = MyApp.SSH.run(host, port, "deploy")
+    assert {:ok, 0, "deploy 2\n", ""} = MyApp.SSH.run(host, port, "deploy")
+  end
+
+  test "accepts client with correct password" do
+    {:ok, instance} = TestServer.SSH.start(credentials: [{"deploy", "hunter2"}])
+    TestServer.SSH.exec(instance, to: fn _, state -> {:reply, {0, "ok\n", ""}, state} end)
+    {host, port} = TestServer.SSH.address(instance)
+
+    assert {:ok, 0, "ok\n", ""} =
+             MyApp.SSH.run(host, port, "deploy", user: "deploy", password: "hunter2")
+  end
+
+  test "rejects client with wrong password" do
+    {:ok, _instance} = TestServer.SSH.start(credentials: [{"deploy", "hunter2"}])
+    {host, port} = TestServer.SSH.address()
+    assert {:error, _} = MyApp.SSH.run(host, port, "anything", user: "deploy", password: "wrong")
+  end
+end