# Split Miner - BPMN process discovery from event logs.
# Authors:
#   imacat@mail.imacat.idv.tw (imacat), 2026/3/10
# AI assistance: Claude Code (Anthropic)

# Copyright (c) 2026 imacat.
#
# 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.
"""Tests for empty and minimal event logs.

Verifies proper error handling when input data is
insufficient for the Split Miner pipeline.
"""
from __future__ import annotations

import unittest

from split_miner import split_miner
from split_miner.bpmn import Node, Task
from split_miner.dfg import DirectlyFollowsGraph


class TestEmptyLog(unittest.TestCase):
    """Tests for empty event log handling."""

    def test_empty_log_dfg(self) -> None:
        """Empty log produces a DFG with no nodes."""
        dfg: DirectlyFollowsGraph = (
            DirectlyFollowsGraph({})
        )
        self.assertEqual(dfg.nodes, set())
        self.assertEqual(dfg.edges, set())

    def test_empty_log_no_sources(self) -> None:
        """Empty DFG has no sources."""
        dfg: DirectlyFollowsGraph = (
            DirectlyFollowsGraph({})
        )
        self.assertEqual(dfg.sources, set())

    def test_empty_log_split_miner(self) -> None:
        """Split Miner handles empty log gracefully."""
        model = split_miner({})
        self.assertEqual(len(model.edges), 0)

    def test_single_event_trace(self) -> None:
        """Single-event trace produces no edges."""
        a: Task = Task("a", "a")
        dfg: DirectlyFollowsGraph = (
            DirectlyFollowsGraph({(a,): 1})
        )
        self.assertEqual(dfg.nodes, {a})
        self.assertEqual(dfg.edges, set())


if __name__ == "__main__":
    unittest.main()