align_sequence_test.py

Here’s a detailed explanation of the align_sequence_test.py file:

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High-level description

This file contains unit tests for the sequence alignment functionality in the Cassiopeia preprocessing pipeline. It tests various aspects of the align_sequences function, including the structure of the output, the behavior with different alignment parameters, and the correctness of alignments for specific input sequences.

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Code Structure

The main class TestAlignSequence inherits from unittest.TestCase and contains several test methods. Each method tests a different aspect of the sequence alignment functionality.

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Symbols

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TestAlignSequence

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Description

This class contains all the unit tests for the sequence alignment functionality.

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Internal Logic

1. Sets up test data in the setUp method.
2. Defines several test methods, each focusing on a specific aspect of the alignment function.

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setUp

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Description

Initializes the test data used across all test methods.

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Internal Logic

1. Creates a DataFrame self.queries with sample sequence data.
2. Sets a reference sequence self.reference.

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test_alignment_dataframe_structure

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Description

Tests the structure of the output DataFrame from the align_sequences function.

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Internal Logic

1. Calls align_sequences with test data.
2. Checks if the output DataFrame has the correct number of rows and expected columns.
3. Verifies that all cell barcodes from the input are present in the output.

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test_extremely_large_gap_open_penalty

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Description

Tests the alignment behavior when using an extremely large gap open penalty.

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Internal Logic

1. Calls align_sequences with a very high gap open penalty (255).
2. Checks that no gaps (insertions or deletions) are present in the resulting alignments.

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test_default_alignment_works

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Description

Tests the correctness of alignments using default parameters.

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Internal Logic

1. Calls align_sequences with default parameters.
2. Compares the resulting CIGAR strings and alignment scores with expected values for each input sequence.

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test_global_alignment

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Description

Tests the global alignment mode of the align_sequences function.

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Internal Logic

1. Calls align_sequences with the method parameter set to “global”.
2. Compares the resulting CIGAR strings and alignment scores with expected values for global alignment.

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Dependencies

The test file depends on the following modules:

• unittest: For creating and running unit tests.
• numpy: For numerical operations.
• pandas: For handling DataFrames.
• cassiopeia: The main package being tested.

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Error Handling

The tests use assertions to check for expected outcomes. If any assertion fails, the test will raise an AssertionError.

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Performance Considerations

These tests are not specifically designed to test performance, but rather the correctness of the alignment function. However, the use of different parameters (like gap penalties and alignment methods) can affect the performance of the alignment algorithm.

In conclusion, this test file provides comprehensive coverage of the sequence alignment functionality in the Cassiopeia preprocessing pipeline, ensuring that the alignment function works correctly under various conditions and with different input parameters.