add 4 new predicates

README.md

@@ -102,18 +102,22 @@ If the above example, we only want to expose our Prometheus metrics if the reque
 
 Unplug provides the following predicates out of the box:
 
-| Predicate                                  | Description                                                                                                |
-| ------------------------------------------ | ---------------------------------------------------------------------------------------------------------- |
-| `Unplug.Predicates.AppConfigEquals`        | Given an application and a key, execute the plug if the configured value matches the expected value        |
-| `Unplug.Predicates.AppConfigNotEquals`     | Given an application and a key, do not execute the plug if the configured value matches the expected value |
-| `Unplug.Predicates.EnvVarEquals`           | Given an environment variable, execute the plug if the configured value matches the expected value         |
-| `Unplug.Predicates.EnvVarNotEquals`        | Given an environment variable, do not execute the plug if the configured value matches the expected value  |
-| `Unplug.Predicates.RequestHeaderEquals`    | Given a request header, execute the plug if the request value matches the expected value                   |
-| `Unplug.Predicates.RequestHeaderNotEquals` | Given a request header, do not execute the plug if the request value matches the expected value            |
-| `Unplug.Predicates.RequestPathEquals`      | Given a request path, execute the plug if the request value matches the expected value                     |
-| `Unplug.Predicates.RequestPathNotEquals`   | Given a request path, do not execute the plug if the request value matches the expected value              |
-| `Unplug.Predicates.RequestPathIn`          | Given a request path, execute the plug if the request value is in the the provided list of values          |
-| `Unplug.Predicates.RequestPathNotIn`       | Given a request path, do not execute the plug if the request value is in the the provided list of values   |
+| Predicate                                  | Description                                                                                                                   |
+| ------------------------------------------ | ----------------------------------------------------------------------------------------------------------------------------- |
+| `Unplug.Predicates.AppConfigEquals`        | Given an application and a key, execute the plug if the configured value matches the expected value                           |
+| `Unplug.Predicates.AppConfigNotEquals`     | Given an application and a key, do not execute the plug if the configured value matches the expected value                    |
+| `Unplug.Predicates.AppConfigIn`            | Given an application and a key, execute the plug if the configured value is in the provided enumerable of values              |
+| `Unplug.Predicates.AppConfigNotIn`         | Given an application and a key, execute the plug if the configured value is not in the provided enumerable of values          |
+| `Unplug.Predicates.EnvVarEquals`           | Given an environment variable, execute the plug if the configured value matches the expected value                            |
+| `Unplug.Predicates.EnvVarNotEquals`        | Given an environment variable, do not execute the plug if the configured value matches the expected value                     |
+| `Unplug.Predicates.EnvVarIn`               | Given an environment variable, execute the plug if the environment variable value is in the provided enumerable of values     |
+| `Unplug.Predicates.EnvVarNotIn`            | Given an environment variable, execute the plug if the environment variable value is not in the provided enumerable of values |
+| `Unplug.Predicates.RequestHeaderEquals`    | Given a request header, execute the plug if the request value matches the expected value                                      |
+| `Unplug.Predicates.RequestHeaderNotEquals` | Given a request header, do not execute the plug if the request value matches the expected value                               |
+| `Unplug.Predicates.RequestPathEquals`      | Given a request path, execute the plug if the request value matches the expected value                                        |
+| `Unplug.Predicates.RequestPathNotEquals`   | Given a request path, do not execute the plug if the request value matches the expected value                                 |
+| `Unplug.Predicates.RequestPathIn`          | Given a request path, execute the plug if the request value is in the the provided enumerable of values                       |
+| `Unplug.Predicates.RequestPathNotIn`       | Given a request path, do not execute the plug if the request value is in the the provided enumerable of values                |
 
 ## Writing Your Own Predicates
 

lib/unplug/predicates/app_config_in.ex

@@ -0,0 +1,20 @@
+defmodule Unplug.Predicates.AppConfigIn do
+  @moduledoc """
+  Given an application and a key, execute the plug if the configured value
+  is in the provided enumerable of values.
+
+  Usage:
+  ```elixir
+  plug Unplug,
+    if: {Unplug.Predicates.AppConfigIn, {:my_app, :some_config, [:enabled, :enabled_again]}},
+    do: MyApp.Plug
+  ```
+  """
+
+  @behaviour Unplug.Predicate
+
+  @impl true
+  def call(_conn, {app, key, expected_values}) do
+    Application.get_env(app, key) in expected_values
+  end
+end

lib/unplug/predicates/app_config_not_in.ex

@@ -0,0 +1,20 @@
+defmodule Unplug.Predicates.AppConfigNotIn do
+  @moduledoc """
+  Given an application and a key, execute the plug if the configured value
+  is not in the provided enumerable of values.
+
+  Usage:
+  ```elixir
+  plug Unplug,
+    if: {Unplug.Predicates.AppConfigNotIn, {:my_app, :some_config, [:enabled, :enabled_again]}},
+    do: MyApp.Plug
+  ```
+  """
+
+  @behaviour Unplug.Predicate
+
+  @impl true
+  def call(conn, opts) do
+    not Unplug.Predicates.AppConfigIn.call(conn, opts)
+  end
+end

lib/unplug/predicates/env_var_in.ex

@@ -0,0 +1,20 @@
+defmodule Unplug.Predicates.EnvVarIn do
+  @moduledoc """
+  Given an environment variable, execute the plug if the environment
+  variable value is in the provided enumerable of values.
+
+  Usage:
+  ```elixir
+  plug Unplug,
+    if: {Unplug.Predicates.EnvVarIn, {"ENABLE_DEBUG", ["true", "1"]}},
+    do: MyApp.Plug
+  ```
+  """
+
+  @behaviour Unplug.Predicate
+
+  @impl true
+  def call(_conn, {env_var, expected_values}) do
+    System.get_env(env_var) in expected_values
+  end
+end

lib/unplug/predicates/env_var_not_in.ex

@@ -0,0 +1,20 @@
+defmodule Unplug.Predicates.EnvVarNotIn do
+  @moduledoc """
+  Given an environment variable, execute the plug if the environment
+  variable value is not in the provided enumerable of values.
+
+  Usage:
+  ```elixir
+  plug Unplug,
+    if: {Unplug.Predicates.EnvVarNotIn, {"ENABLE_DEBUG", ["true", "1"]}},
+    do: MyApp.Plug
+  ```
+  """
+
+  @behaviour Unplug.Predicate
+
+  @impl true
+  def call(conn, opts) do
+    not Unplug.Predicates.EnvVarIn.call(conn, opts)
+  end
+end

lib/unplug/predicates/request_path_in.ex

@@ -1,7 +1,7 @@
 defmodule Unplug.Predicates.RequestPathIn do
   @moduledoc """
   Given a request path, execute the plug if the request value is in
-  the the provided list of values.
+  the the provided enumerable of values.
 
   Usage:
   ```elixir

lib/unplug/predicates/request_path_not_in.ex

@@ -1,7 +1,7 @@
 defmodule Unplug.Predicates.RequestPathNotIn do
   @moduledoc """
   Given a request path, do not execute the plug if the request value is
-  in the the provided list of values.
+  in the the provided enumerable of values.
 
   Usage:
   ```elixir

test/predicates/app_config_in_test.exs

@@ -0,0 +1,27 @@
+defmodule Unplug.Predicates.AppConfigInTest do
+  use ExUnit.Case, async: false
+  use Plug.Test
+
+  test "should return true if the application config key is in the list" do
+    Application.put_env(:unplug, :app_config_test, "some_config_string")
+    Application.put_env(:unplug, :app_config_test_two, "some_other_config_string")
+    conn = conn(:get, "/")
+
+    assert Unplug.Predicates.AppConfigIn.call(
+             conn,
+             {:unplug, :app_config_test, ["some_config_string", "some_other_string"]}
+           )
+
+    assert Unplug.Predicates.AppConfigIn.call(
+             conn,
+             {:unplug, :app_config_test_two, ["some_config_string", "some_other_config_string"]}
+           )
+  end
+
+  test "should return false if the application config key is NOT in the list" do
+    Application.put_env(:unplug, :app_config_test, "some_config_string")
+    conn = conn(:get, "/")
+
+    refute Unplug.Predicates.AppConfigIn.call(conn, {:unplug, :app_config_test, ["invalid"]})
+  end
+end

test/predicates/app_config_not_in_test.exs

@@ -0,0 +1,27 @@
+defmodule Unplug.Predicates.AppConfigNotInTest do
+  use ExUnit.Case, async: false
+  use Plug.Test
+
+  test "should return true if the application config key is NOT in the list" do
+    Application.put_env(:unplug, :app_config_test, "some_config_string")
+    Application.put_env(:unplug, :app_config_test_two, "some_other_config_string")
+    conn = conn(:get, "/")
+
+    refute Unplug.Predicates.AppConfigNotIn.call(
+             conn,
+             {:unplug, :app_config_test, ["some_config_string", "some_other_string"]}
+           )
+
+    refute Unplug.Predicates.AppConfigNotIn.call(
+             conn,
+             {:unplug, :app_config_test_two, ["some_config_string", "some_other_config_string"]}
+           )
+  end
+
+  test "should return false if the application config key is in the list" do
+    Application.put_env(:unplug, :app_config_test, "some_config_string")
+    conn = conn(:get, "/")
+
+    assert Unplug.Predicates.AppConfigNotIn.call(conn, {:unplug, :app_config_test, ["invalid"]})
+  end
+end

test/predicates/env_var_in_test.exs

@@ -0,0 +1,18 @@
+defmodule Unplug.Predicates.EnvVarInTest do
+  use ExUnit.Case, async: false
+  use Plug.Test
+
+  test "should return true if the env var is in the list of acceptable keys" do
+    System.put_env("UNPLUG_ENV_VAR", "some_config_string")
+    conn = conn(:get, "/")
+
+    assert Unplug.Predicates.EnvVarIn.call(conn, {"UNPLUG_ENV_VAR", ["some_config_string", "some_other_config_string"]})
+  end
+
+  test "should return false if the env var is not in the list of acceptable keys" do
+    System.put_env("UNPLUG_ENV_VAR", "some_config_string")
+    conn = conn(:get, "/")
+
+    refute Unplug.Predicates.EnvVarIn.call(conn, {"UNPLUG_ENV_VAR", ["invalid", "still_invalid"]})
+  end
+end

test/predicates/env_var_not_in_test.exs

@@ -0,0 +1,21 @@
+defmodule Unplug.Predicates.EnvVarNotInTest do
+  use ExUnit.Case, async: false
+  use Plug.Test
+
+  test "should return false if the env var is in the list of acceptable keys" do
+    System.put_env("UNPLUG_ENV_VAR", "some_config_string")
+    conn = conn(:get, "/")
+
+    refute Unplug.Predicates.EnvVarNotIn.call(
+             conn,
+             {"UNPLUG_ENV_VAR", ["some_config_string", "some_other_config_string"]}
+           )
+  end
+
+  test "should return true if the env var is not in the list of acceptable keys" do
+    System.put_env("UNPLUG_ENV_VAR", "some_config_string")
+    conn = conn(:get, "/")
+
+    assert Unplug.Predicates.EnvVarNotIn.call(conn, {"UNPLUG_ENV_VAR", ["invalid", "still_invalid"]})
+  end
+end