add test for parse_requirements function

tests/_data/imports.txt

@@ -0,0 +1,3 @@
+pandas==2.0.0
+numpy>=1.2.3
+torch<4.0.0

tests/_data/imports_any_version.txt

@@ -0,0 +1,4 @@
+numpy
+pandas==2.0.0
+tensorflow
+torch<4.0.0

tests/_data/imports_no_version.txt

@@ -0,0 +1,3 @@
+pandas
+tensorflow
+torch

tests/test_pipreqs.py

@@ -39,14 +39,35 @@ def setUp(self):
         self.modules2 = ["beautifulsoup4"]
         self.local = ["docopt", "requests", "nose", "pyflakes"]
         self.project = os.path.join(os.path.dirname(__file__), "_data")
+        self.empty_filepath = os.path.join(self.project, "empty.txt")
+        self.imports_filepath = os.path.join(self.project, "imports.txt")
+        self.imports_no_version_filepath = os.path.join(self.project, "imports_no_version.txt")
+        self.imports_any_version_filepath = os.path.join(self.project, "imports_any_version.txt")
+        self.non_existent_filepath = os.path.join(self.project, "non_existent_file.txt")
+
+        self.parsed_packages = [
+            {"name": "pandas", "version": "2.0.0"},
+            {"name": "numpy", "version": "1.2.3"},
+            {"name": "torch", "version": "4.0.0"},
+        ]
+
+        self.parsed_packages_no_version = [
+            {"name": "pandas", "version": None},
+            {"name": "tensorflow", "version": None},
+            {"name": "torch", "version": None},
+        ]
+
+        self.parsed_packages_any_version = [
+            {"name": "numpy", "version": None},
+            {"name": "pandas", "version": "2.0.0"},
+            {"name": "tensorflow", "version": None},
+            {"name": "torch", "version": "4.0.0"},
+        ]
+
         self.project_clean = os.path.join(os.path.dirname(__file__), "_data_clean")
         self.project_invalid = os.path.join(os.path.dirname(__file__), "_invalid_data")
-        self.project_with_ignore_directory = os.path.join(
-            os.path.dirname(__file__), "_data_ignore"
-        )
-        self.project_with_duplicated_deps = os.path.join(
-            os.path.dirname(__file__), "_data_duplicated_deps"
-        )
+        self.project_with_ignore_directory = os.path.join(os.path.dirname(__file__), "_data_ignore")
+        self.project_with_duplicated_deps = os.path.join(os.path.dirname(__file__), "_data_duplicated_deps")
         self.requirements_path = os.path.join(self.project, "requirements.txt")
         self.alt_requirement_path = os.path.join(self.project, "requirements2.txt")
 
@@ -223,12 +244,8 @@ def test_get_import_name_without_alias(self):
         """
         import_name_with_alias = "requests as R"
         expected_import_name_without_alias = "requests"
-        import_name_without_aliases = pipreqs.get_name_without_alias(
-            import_name_with_alias
-        )
-        self.assertEqual(
-            import_name_without_aliases, expected_import_name_without_alias
-        )
+        import_name_without_aliases = pipreqs.get_name_without_alias(import_name_with_alias)
+        self.assertEqual(import_name_without_aliases, expected_import_name_without_alias)
 
     def test_custom_pypi_server(self):
         """
@@ -267,9 +284,7 @@ def test_ignored_directory(self):
                 "--mode": None,
             }
         )
-        with open(
-            os.path.join(self.project_with_ignore_directory, "requirements.txt"), "r"
-        ) as f:
+        with open(os.path.join(self.project_with_ignore_directory, "requirements.txt"), "r") as f:
             data = f.read().lower()
             for item in ["click", "getpass"]:
                 self.assertFalse(item.lower() in data)
@@ -292,9 +307,7 @@ def test_dynamic_version_no_pin_scheme(self):
                 "--mode": "no-pin",
             }
         )
-        with open(
-            os.path.join(self.project_with_ignore_directory, "requirements.txt"), "r"
-        ) as f:
+        with open(os.path.join(self.project_with_ignore_directory, "requirements.txt"), "r") as f:
             data = f.read().lower()
             for item in ["beautifulsoup4", "boto"]:
                 self.assertTrue(item.lower() in data)
@@ -317,9 +330,7 @@ def test_dynamic_version_gt_scheme(self):
                 "--mode": "gt",
             }
         )
-        with open(
-            os.path.join(self.project_with_ignore_directory, "requirements.txt"), "r"
-        ) as f:
+        with open(os.path.join(self.project_with_ignore_directory, "requirements.txt"), "r") as f:
             data = f.readlines()
             for item in data:
                 symbol = ">="
@@ -344,9 +355,7 @@ def test_dynamic_version_compat_scheme(self):
                 "--mode": "compat",
             }
         )
-        with open(
-            os.path.join(self.project_with_ignore_directory, "requirements.txt"), "r"
-        ) as f:
+        with open(os.path.join(self.project_with_ignore_directory, "requirements.txt"), "r") as f:
             data = f.readlines()
             for item in data:
                 symbol = "~="
@@ -472,6 +481,31 @@ def test_output_requirements(self):
             stdout_content = capturedOutput.getvalue().lower()
             self.assertTrue(file_content == stdout_content)
 
+    def test_parse_requirements(self):
+        """
+        Test parse_requirements function
+        """
+        test_cases = [
+            (self.empty_filepath, []),  # empty file
+            (self.imports_filepath, self.parsed_packages),  # imports with versions
+            (
+                self.imports_no_version_filepath,
+                self.parsed_packages_no_version,
+            ),  # imports without versions
+            (
+                self.imports_any_version_filepath,
+                self.parsed_packages_any_version,
+            ),  # imports with and without versions
+        ]
+
+        for test in test_cases:
+            with self.subTest(test):
+                filename, expected_parsed_requirements = test
+
+                parsed_requirements = pipreqs.parse_requirements(filename)
+
+                self.assertListEqual(parsed_requirements, expected_parsed_requirements)
+
     def tearDown(self):
         """
         Remove requiremnts.txt files that were written