[feat]: Adding handlers structure

minushalf/handlers/__init__.py

@@ -0,0 +1,4 @@
+"""
+handlers to process the data passed by the user in the CLI
+"""
+from .base_handler import BaseHandler

minushalf/handlers/base_handler.py

@@ -0,0 +1,24 @@
+"""
+Base class to all Handlers
+"""
+from minushalf.interfaces import Handler
+
+
+class BaseHandler(Handler):
+    """
+    The default chaining behavior can be implemented inside a base handler
+    class.
+    """
+
+    _next_handler: Handler = None
+
+    def set_next(self, handler: Handler) -> Handler:
+        self._next_handler = handler
+        # Returning a handler from here will let us link handlers in a useful way
+        return handler
+
+    def handle(self, request: any) -> str:
+        if self._next_handler:
+            return self._next_handler.handle(request)
+
+        return ''

minushalf/interfaces/__init__.py

@@ -6,3 +6,4 @@
 from .band_projection_file import BandProjectionFile
 from .runner import Runner
 from .correction import Correction
+from .handler import Handler

minushalf/interfaces/handler.py

@@ -0,0 +1,19 @@
+"""
+Interface for the handler class
+"""
+from abc import ABC, abstractmethod
+from typing import Optional
+
+
+class Handler(ABC):
+    """
+    The Handler interface declares a method for building the chain of handlers.
+    It also declares a method for executing a request.
+    """
+    @abstractmethod
+    def set_next(self, handler: any) -> any:
+        pass
+
+    @abstractmethod
+    def handle(self, request) -> Optional[str]:
+        pass

tests/unit/handlers/test_base_handler.py

@@ -0,0 +1,49 @@
+"""
+Test base handler class
+"""
+from minushalf.handlers import BaseHandler
+from pytest_mock import MockerFixture
+
+
+def text_set_next():
+    """
+    Test function that sets the next handler
+    """
+    base_handler = BaseHandler()
+    next_handler = BaseHandler()
+
+    res = base_handler.set_next(next_handler)
+
+    assert base_handler._next_handler == next_handler
+    assert res == next_handler
+
+
+def test_handle_when_next_handler_not_defined():
+    """
+    Test function that activates the next handler when
+    next handler isn't defined
+    """
+    base_handler = BaseHandler()
+
+    assert base_handler.handle({}) == ''
+
+
+def test_handle_when_next_handler_is_defined(mocker: MockerFixture):
+    """
+    Test function that activates the next handler when
+    next handler is defined
+    """
+    base_handler = BaseHandler()
+    next_handler = BaseHandler()
+
+    ## mock and spy next handler
+    mocker.patch.object(next_handler,
+                        'handle',
+                        return_value='Test',
+                        autospec=True)
+    spy = mocker.spy(next_handler, 'handle')
+
+    base_handler.set_next(next_handler)
+
+    assert base_handler.handle({}) == 'Test'
+    assert spy.assert_called_once_with({})