diff --git a/tests/test_minimap2.py b/tests/test_minimap2.py
new file mode 100644
index 0000000..eae54da
--- /dev/null
+++ b/tests/test_minimap2.py
@@ -0,0 +1,152 @@
+import unittest
+from unittest.mock import patch, mock_open
+
+from scripts.minimap2 import *
+
+class TestCutadapt(unittest.TestCase):
+    def test_cutadapt(self):
+        # Using mocks to ensure that the cutadapt function is
+        # being called correctly without actually running external shell commands
+        with patch('subprocess.check_call') as mock_check_call:
+            mock_check_call.return_value = 0
+
+            with tempfile.NamedTemporaryFile() as fq1, tempfile.NamedTemporaryFile() as fq2:
+                of1_name, of2_name = cutadapt(fq1.name, fq2.name)
+
+            # Check that the mock was called with the correct arguments
+            mock_check_call.assert_called_once_with([
+                'cutadapt', '-a', 'AGATCGGAAGAGC', '-A', 'AGATCGGAAGAGC',
+                '-o', of1_name, '-p', of2_name, '-j', '1', '-m', '10',
+                '--quiet', fq1.name, fq2.name
+            ])
+
+
+class TestMakeFilename(unittest.TestCase):
+    prefix = "test"
+    suffix = "txt"
+    def test_make_filename_doesnt_exist(self):
+        with tempfile.TemporaryDirectory() as temp_dir:
+            filename = make_filename(temp_dir, self.prefix, self.suffix)
+
+            expected_filename = os.path.join(temp_dir, f"{self.prefix}.{self.suffix}")
+            self.assertEqual(filename, expected_filename)
+
+    def test_make_filename_without_replace(self):
+        with tempfile.TemporaryDirectory() as temp_dir:
+            existing_filename = os.path.join(temp_dir, f"{self.prefix}.{self.suffix}")
+            with open(existing_filename, 'w') as temp_file:
+                temp_file.write("Sample data")
+
+            # Call the function with replace=False
+            with patch('sys.exit') as mock_exit, patch('builtins.print') as mock_print:
+                filename = make_filename(temp_dir, self.prefix, self.suffix, replace=False)
+
+            expected_filename = os.path.join(temp_dir, f"{self.prefix}.{self.suffix}")
+            self.assertEqual(filename, expected_filename)
+
+            # Assert that the function prints the expected message and exits
+            mock_print.assert_called_once_with(
+                f"Output file {expected_filename} already exists, use --replace to overwrite"
+            )
+            mock_exit.assert_called_once()
+
+    def test_make_filename_with_replace(self):
+        with tempfile.TemporaryDirectory() as temp_dir:
+            existing_filename = os.path.join(temp_dir, f"{self.prefix}.{self.suffix}")
+            with open(existing_filename, 'w') as temp_file:
+                temp_file.write("Sample data")
+
+            # Call the function with replace=True
+            with patch('sys.exit') as mock_exit:
+                filename = make_filename(temp_dir, self.prefix, self.suffix, replace=True)
+
+            expected_filename = os.path.join(temp_dir, f"{self.prefix}.{self.suffix}")
+            self.assertEqual(filename, expected_filename)
+
+            # Assert that the function doesnt exit when replace=True
+            mock_exit.assert_not_called()
+
+
+class TestProcess(unittest.TestCase):
+    def setUp(self):
+        self.expected_counts = {26272: {'~26273T': {'label': 'aa:E:G10V', 'count': 0.5}},
+                                25923: {'~25924T': {'label': 'aa:orf3a:P178S', 'count': 0.5}}}
+
+    def test_process(self):
+        counts, coverage = process(fq1="data/unit-tests/minimap2_mutations-coverage_1.fastq",
+                         fq2="data/unit-tests/minimap2_mutations-coverage_2.fastq",
+                         ref="data/NC_045512.fa", nthread=3, binpath='minimap2', limit=None)
+        self.assertEqual(self.expected_counts, counts)
+
+    def test_get_frequencies(self):
+        # Zero denominator
+        res = [
+            {'diff': [('-', 100, 'A')], 'mutations': ['Mutation1']},
+            {'diff': [('+', 200, 'C')], 'mutations': ['Mutation2']}
+        ]
+        coverage = {100: 0, 200: 0}
+
+        result = get_frequencies(res, coverage)
+        self.assertEqual(result, {})
+
+        # Non-zero denominator
+        res = [
+            {'diff': [('-', 100, 'A')], 'mutations': ['Mutation1']},
+            {'diff': [('+', 200, 'C')], 'mutations': ['Mutation2']}
+        ]
+        coverage = {100: 10, 200: 6}
+
+        result = get_frequencies(res, coverage)
+        expected_result = {100: {'-101.A': {'count': 0.1, 'label': 'Mutation1'}},
+                           200: {'+201.C': {'count': 0.16666666666666666, 'label': 'Mutation2'}}}
+
+        self.assertEqual(result, expected_result)
+
+    def test_write_frequencies(self):
+        coverage = {i:0 for i in range(29903)}
+
+        expected_output = 'position,label,mutation,frequency,coverage\n' \
+                          '26272,~26273T,aa:E:G10V,0.5,0\n' \
+                          '25923,~25924T,aa:orf3a:P178S,0.5,0\n'
+
+        # Mock the open function
+        with patch('builtins.open', mock_open()) as mock_file:
+            outfile = 'test_output.csv'
+            write_frequencies(self.expected_counts, coverage, outfile)
+
+            mock_file.assert_called_once_with(outfile, 'w')
+
+            handle = mock_file()
+            calls = handle.write.call_args_list
+            written_content = ''.join(call[0][0] for call in calls)
+
+            self.assertEqual(written_content, expected_output)
+
+    def test_write_coverage(self):
+        coverage = {
+            0: 10,
+            1: 6,
+            2: 15
+        }
+
+        expected_output = 'position,coverage\n' \
+                          '0,10\n' \
+                          '1,6\n' \
+                          '2,15\n'
+
+        # Mock the open function
+        with patch('builtins.open', mock_open()) as mock_file:
+            outfile = 'test_coverage_output.csv'
+            write_coverage(coverage, outfile)
+
+            mock_file.assert_called_once_with(outfile, 'w')
+
+            handle = mock_file()
+            calls = handle.write.call_args_list
+            written_content = ''.join(call[0][0] for call in calls)
+
+            self.assertEqual(written_content, expected_output)
+
+
+if __name__ == '__main__':
+    unittest.main()
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