Split MockContext into Standalone and multi-group (#42)

ahsimb · tkilias · web-flow · commit 81abae735e2d · 2023-10-24T14:07:12.000+01:00
* Split MockContext into Standalone and multi-group

* Fixed compatibility issue with the scalar parameters being wrapped in a container.

* Update exasol_udf_mock_python/mock_context.py

Co-authored-by: Torsten Kilias &lt;tkilias@users.noreply.github.com&gt;

* Update exasol_udf_mock_python/mock_context.py

Co-authored-by: Torsten Kilias &lt;tkilias@users.noreply.github.com&gt;

* Update exasol_udf_mock_python/mock_context.py

Co-authored-by: Torsten Kilias &lt;tkilias@users.noreply.github.com&gt;

* Update exasol_udf_mock_python/mock_context.py

Co-authored-by: Torsten Kilias &lt;tkilias@users.noreply.github.com&gt;

* Refactoring following a review

* Making the MockContext tests running under Python 3.8

* Updated MockContext test_scroll test

* validate_emit is taken out of the StandaloneMockContext class

---------

Co-authored-by: Torsten Kilias &lt;tkilias@users.noreply.github.com&gt;
diff --git a/exasol_udf_mock_python/mock_context.py b/exasol_udf_mock_python/mock_context.py
@@ -1,4 +1,5 @@
-from typing import List, Tuple, Iterator
+from typing import List, Tuple, Iterator, Iterable, Any, Optional, Union
+from functools import wraps
 
 import pandas as pd
 
@@ -8,50 +9,190 @@
 from exasol_udf_mock_python.udf_context import UDFContext
 
 
+def check_context(f):
+    """
+    Decorator checking that a MockContext object has valid current group context.
+    Raises a RuntimeError if this is not the case.
+    """
+    @wraps(f)
+    def wrapper(self, *args, **kwargs):
+        if self.no_context:
+            raise RuntimeError('Calling UDFContext interface when the current group context '
+                               'is invalid is disallowed')
+        return f(self, *args, **kwargs)
+
+    return wrapper
+
+
+def validate_emit(row: Tuple, columns: List[Column]):
+    """
+    Validates that a data row to be emitted corresponds to the definition of the output columns.
+    The number of elements in the row should match the number of columns and the type of each
+    element should match the type of the correspondent column. Raises a ValueError if the first
+    condition is false or a TypeError if the second condition is false.
+
+    :param row:         Data row
+    :param columns:     Column definition.
+    """
+    if len(row) != len(columns):
+        raise ValueError(f"row {row} has not the same number of values as columns are defined")
+    for i, column in enumerate(columns):
+        if row[i] is not None and not isinstance(row[i], column.type):
+            raise TypeError(f"Value {row[i]} ({type(row[i])}) at position {i} is not a {column.type}")
+
+
 class MockContext(UDFContext):
+    """
+    Implementation of generic UDF Mock Context interface for a SET UDF with groups.
+    This class allows iterating over groups. The functionality of the UDF Context are applicable
+    for the current input group.
+
+    Call `next_group` to iterate over groups. The `output_groups` property provides the emit
+    output for all groups iterated so far including the output for the current group.
+
+    Calling any function of the UDFContext interface when the group iterator has passed the end
+    or before the first call to the `next_group` is illegal and will cause a RuntimeException.
+    """
 
     def __init__(self, input_groups: Iterator[Group], metadata: MockMetaData):
+        """
+        :param input_groups:    Input groups. Each group object should contain input rows for the group.
+
+        :param metadata:        The mock metadata object.
+        """
+
         self._input_groups = input_groups
-        self._output_groups = []
-        self._input_group = None  # type: Group
-        self._output_group_list = None  # type: List
-        self._output_group = None  # type: Group
-        self._iter = None  # type: Iterator[Tuple]
-        self._len = None  # type: int
         self._metadata = metadata
-        self._name_position_map = \
-            {column.name: position
-             for position, column
-             in enumerate(metadata.input_columns)}
+        """ Mock context for the current group """
+        self._current_context: Optional[StandaloneMockContext] = None
+        """ Output for all groups """
+        self._previous_output: List[Group] = []
+
+    @property
+    def no_context(self) -> bool:
+        """Returns True if the current group context is invalid"""
+        return self._current_context is None
 
-    def _next_group(self):
+    def next_group(self) -> bool:
+        """
+        Moves group iterator to the next group.
+        Returns False if the iterator gets beyond the last group. Returns True otherwise.
+        """
+
+        # Save output of the current group
+        if self._current_context is not None:
+            self._previous_output.append(Group(self._current_context.output))
+            self._current_context = None
+
+        # Try get to the next input group
         try:
-            self._input_group = next(self._input_groups)
+            input_group = next(self._input_groups)
         except StopIteration as e:
-            self._data = None
-            self._output_group_list = None
-            self._output_group = None
-            self._input_group = None
-            self._iter = None
-            self._len = None
             return False
-        self._len = len(self._input_group)
-        if self._len == 0:
-            self._data = None
-            self._output_group_list = None
-            self._output_group = None
-            self._input_group = None
-            self._iter = None
-            self._len = None
-            raise RuntimeError("Empty input groups are not allowd")
-        self._output_group_list = []
-        self._output_group = Group(self._output_group_list)
-        self._output_groups.append(self._output_group)
-        self._iter = iter(self._input_group)
-        self.next()
+        if len(input_group) == 0:
+            raise RuntimeError("Empty input groups are not allowed")
+
+        # Create Mock Context for the new input group
+        self._current_context = StandaloneMockContext(input_group, self._metadata)
         return True
 
-    def _is_positive_integer(self, value):
+    @property
+    def output_groups(self):
+        """
+        Output of all groups including the current one.
+        """
+        if self._current_context is None:
+            return self._previous_output
+        else:
+            groups = list(self._previous_output)
+            groups.append(Group(self._current_context.output))
+            return groups
+
+    @check_context
+    def __getattr__(self, name):
+        return getattr(self._current_context, name)
+
+    @check_context
+    def get_dataframe(self, num_rows: Union[str, int], start_col: int = 0) -> Optional[pd.DataFrame]:
+        return self._current_context.get_dataframe(num_rows, start_col)
+
+    @check_context
+    def next(self, reset: bool = False) -> bool:
+        return self._current_context.next(reset)
+
+    @check_context
+    def size(self) -> int:
+        return self._current_context.size()
+
+    @check_context
+    def reset(self) -> None:
+        self._current_context.reset()
+
+    @check_context
+    def emit(self, *args) -> None:
+        self._current_context.emit(*args)
+
+
+def get_scalar_input(inp: Any) -> Iterable[Tuple[Any, ...]]:
+    """
+    Figures out if the SCALAR parameters are provided as a scalar value or a tuple
+    and also if there is a wrapping container around.
+    Unless the parameters are already in a wrapping container returns parameters as a tuple wrapped
+    into a one-item list, e.g [(param1[, param2, ...)]. Otherwise, returns the original input.
+
+    :param  inp:        Input parameters.
+    """
+
+    if isinstance(inp, Iterable) and not isinstance(inp, str):
+        row1 = next(iter(inp))
+        if isinstance(row1, Iterable) and not isinstance(row1, str):
+            return inp
+        else:
+            return [inp]
+    else:
+        return [(inp,)]
+
+
+class StandaloneMockContext(UDFContext):
+    """
+    Implementation of generic UDF Mock Context interface a SCALAR UDF or a SET UDF with no groups.
+
+    For Emit UDFs the output in the form of the list of tuples can be
+    accessed by reading the `output` property.
+    """
+
+    def __init__(self, inp: Any, metadata: MockMetaData):
+        """
+        :param  inp:        Input rows for a SET UDF or parameters for a SCALAR one.
+                            In the former case the input object must be an iterable of rows. This, for example,
+                            can be a Group object. It must implement the __len__ method. Each data row must be
+                            an indexable container, e.g. a tuple.
+                            In the SCALAR case the input can be a scalar value, or tuple. This can also be wrapped
+                            in an iterable container, similar to the SET case.
+
+        :param metadata:    The mock metadata object.
+        """
+        if metadata.input_type.upper() == 'SCALAR':
+            self._input = get_scalar_input(inp)
+        else:
+            self._input = inp
+        self._metadata = metadata
+        self._data: Optional[Any] = None
+        self._iter: Optional[Iterator[Tuple[Any, ...]]] = None
+        self._name_position_map = \
+            {column.name: position
+             for position, column
+             in enumerate(metadata.input_columns)}
+        self._output = []
+        self.next(reset=True)
+
+    @property
+    def output(self) -> List[Tuple[Any, ...]]:
+        """Emitted output so far"""
+        return self._output
+
+    @staticmethod
+    def _is_positive_integer(value):
         return value is not None and isinstance(value, int) and value > 0
 
     def get_dataframe(self, num_rows='all', start_col=0):
@@ -80,26 +221,26 @@ def get_dataframe(self, num_rows='all', start_col=0):
         return df
 
     def __getattr__(self, name):
-        return self._data[self._name_position_map[name]]
+        return None if self._data is None else self._data[self._name_position_map[name]]
 
     def next(self, reset: bool = False):
-        if reset:
+        if self._iter is None or reset:
             self.reset()
         else:
             try:
                 new_data = next(self._iter)
                 self._data = new_data
-                self._validate_tuples(self._data, self._metadata.input_columns)
+                validate_emit(self._data, self._metadata.input_columns)
                 return True
             except StopIteration as e:
                 self._data = None
                 return False
 
     def size(self):
-        return self._len
+        return len(self._input)
 
     def reset(self):
-        self._iter = iter(self._input_group)
+        self._iter = iter(self._input)
         self.next()
 
     def emit(self, *args):
@@ -108,13 +249,5 @@ def emit(self, *args):
         else:
             tuples = [args]
         for row in tuples:
-            self._validate_tuples(row, self._metadata.output_columns)
-        self._output_group_list.extend(tuples)
-        return
-
-    def _validate_tuples(self, row: Tuple, columns: List[Column]):
-        if len(row) != len(columns):
-            raise Exception(f"row {row} has not the same number of values as columns are defined")
-        for i, column in enumerate(columns):
-            if row[i] is not None and not isinstance(row[i], column.type):
-                raise TypeError(f"Value {row[i]} ({type(row[i])}) at position {i} is not a {column.type}")
+            validate_emit(row, self._metadata.output_columns)
+        self._output.extend(tuples)
diff --git a/exasol_udf_mock_python/udf_mock_executor.py b/exasol_udf_mock_python/udf_mock_executor.py
@@ -7,7 +7,7 @@
 
 
 def _loop_groups(ctx:MockContext, exa:MockExaEnvironment, runfunc:Callable):
-    while ctx._next_group():
+    while ctx.next_group():
         _wrapped_run(ctx, exa, runfunc)
 
 
@@ -77,4 +77,4 @@ def run(self,
             finally:
                 if "cleanup" in exec_globals:
                     self._exec_cleanup(exec_globals)
-            return ctx._output_groups
+            return ctx.output_groups
diff --git a/tests/test_mock_context.py b/tests/test_mock_context.py
@@ -0,0 +1,69 @@
+import pytest
+import pandas as pd
+
+from exasol_udf_mock_python.group import Group
+from exasol_udf_mock_python.mock_context import MockContext
+from tests.test_mock_context_standalone import meta_set_emits
+
+
+@pytest.fixture
+def context_set_emits(meta_set_emits):
+    pets = Group([(1, 'cat'), (2, 'dog')])
+    bugs = Group([(3, 'ant'), (4, 'bee'), (5, 'beetle')])
+    groups = [pets, bugs]
+    return MockContext(iter(groups), meta_set_emits)
+
+
+def test_scroll(context_set_emits):
+    groups = []
+    while context_set_emits.next_group():
+        group = [context_set_emits.t2]
+        while context_set_emits.next():
+            group.append(context_set_emits.t2)
+        groups.append(group)
+    assert groups == [['cat', 'dog'], ['ant', 'bee', 'beetle']]
+
+
+def test_output_groups(context_set_emits):
+    context_set_emits.next_group()
+    context_set_emits.emit(1, 'cat')
+    context_set_emits.emit(2, 'dog')
+    context_set_emits.next_group()
+    context_set_emits.emit(3, 'ant')
+    context_set_emits.emit(4, 'bee')
+    context_set_emits.emit(5, 'beetle')
+    context_set_emits.next_group()
+    assert len(context_set_emits.output_groups) == 2
+    assert context_set_emits.output_groups[0] == Group([(1, 'cat'), (2, 'dog')])
+    assert context_set_emits.output_groups[1] == Group([(3, 'ant'), (4, 'bee'), (5, 'beetle')])
+
+
+def test_output_groups_partial(context_set_emits):
+    context_set_emits.next_group()
+    context_set_emits.emit(1, 'cat')
+    context_set_emits.emit(2, 'dog')
+    context_set_emits.next_group()
+    context_set_emits.emit(3, 'ant')
+    context_set_emits.emit(4, 'bee')
+    assert len(context_set_emits.output_groups) == 2
+    assert context_set_emits.output_groups[0] == Group([(1, 'cat'), (2, 'dog')])
+    assert context_set_emits.output_groups[1] == Group([(3, 'ant'), (4, 'bee')])
+
+
+def test_no_context_exception(context_set_emits):
+
+    for _ in range(3):
+        context_set_emits.next_group()
+
+    with pytest.raises(RuntimeError):
+        _ = context_set_emits.t2
+    with pytest.raises(RuntimeError):
+        _ = context_set_emits.get_dataframe()
+    with pytest.raises(RuntimeError):
+        context_set_emits.next()
+    with pytest.raises(RuntimeError):
+        _ = context_set_emits.size()
+    with pytest.raises(RuntimeError):
+        context_set_emits.reset()
+    with pytest.raises(RuntimeError):
+        context_set_emits.emit(1, 'cat')
diff --git a/tests/test_mock_context_standalone.py b/tests/test_mock_context_standalone.py
