frontend: Introduce `test_frontend` to easily test model related code

Signed-off-by: Alexandre Terrasa <alexandre@moz-code.org>

diff --git a/src/frontend/test_frontend.nit b/src/frontend/test_frontend.nit
new file mode 100644 (file)
index 0000000..2503e1e
--- /dev/null
+++ b/src/frontend/test_frontend.nit
@@ -0,0 +1,76 @@
+# This file is part of NIT ( http://www.nitlanguage.org ).
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Testing Model with `nitunit`
+#
+# This module introduce useful tools if you want to test Model with nitunit.
+# It provides an abstract test suite `TestModel` that can load a `Model` from
+# Nit files.
+#
+# See `TestModel::test_src`.
+module test_frontend is test
+
+import frontend
+import frontend::parse_examples
+
+# An abstract NitUnit that loads a `Model` from Nit files.
+#
+# To define a custom test using `TestModel`:
+#
+# ~~~
+# class MyTest
+#      super TestModel
+#      test
+#
+#      redef var test_src = "path/to/files"
+#
+#      fun my_test is test do
+#              assert test_model.mmodules.length == 10
+#      end
+# end
+# ~~~
+abstract class TestModel
+
+       # Path this unit test is executed in
+       var test_path: String = "NIT_TESTING_PATH".environ.dirname is lazy
+
+       # Test program to compile
+       #
+       # Change this source in your test suite.
+       # Default is `$NIT_DIR/tests/test_prog`.
+       #
+       # You can use either a file or a directory.
+       var test_src: String = "NIT_DIR".environ / "tests/test_prog" is lazy
+
+       # ToolContext used for the ModelBuilder
+       var test_context = new ToolContext
+
+       # Model used for tests
+       var test_model = new Model
+
+       # ModelBuilder used for tests
+       var test_builder = new ModelBuilder(test_model, test_context)
+
+       # Mainmodule used for tests
+       var test_main: MModule is noinit
+
+       # Build the test environment
+       fun build_test_env is before do
+               var mmodules = test_builder.parse_full([test_src])
+               test_builder.run_phases
+               test_context.run_global_phases(mmodules)
+               var mainmodule = test_context.make_main_module(mmodules)
+               test_main = mainmodule
+       end
+end