Add support for License-Expression parsing (PEP 639)

CHANGELOG.md

@@ -1,5 +1,11 @@
 ## CHANGELOG
 
+### 6.0.0
+
+* Added support for `License-Expression` metadata field, see [PEP 639](https://peps.python.org/pep-0639/)
+* Added `--from=expression` option
+* Breaking change: The `--from=all` output now includes the `License-Expression` value
+
 ### 5.0.0
 
 * Dropped support Python 3.8

piplicenses.py

@@ -162,6 +162,9 @@ def normalize_pkg_name(pkg_name: str) -> str:
         lambda metadata: metadata.get("maintainer-email"),
     ],
     "license": [lambda metadata: metadata.get("license")],
+    "license_expression": [
+        lambda metadata: metadata.get("license-expression")
+    ],
     "summary": [lambda metadata: metadata.get("summary")],
 }
 
@@ -171,6 +174,7 @@ def normalize_pkg_name(pkg_name: str) -> str:
     "Description": "summary",
     "License-Metadata": "license",
     "License-Classifier": "license_classifier",
+    "License-Expression": "license_expression",
 }
 
 
@@ -312,6 +316,7 @@ def get_python_sys_path(executable: str) -> list[str]:
             args.from_,
             cast(List[str], pkg_info["license_classifier"]),
             cast(str, pkg_info["license"]),
+            cast(str, pkg_info["license_expression"]),
         )
 
         if fail_on_licenses:
@@ -374,6 +379,7 @@ def create_licenses_table(
                     args.from_,
                     cast(List[str], pkg["license_classifier"]),
                     cast(str, pkg["license"]),
+                    cast(str, pkg["license_expression"]),
                 )
                 license_str = "; ".join(sorted(license_set))
                 row.append(license_str)
@@ -399,6 +405,7 @@ def create_summary_table(args: CustomNamespace) -> PrettyTable:
                     args.from_,
                     cast(List[str], pkg["license_classifier"]),
                     cast(str, pkg["license"]),
+                    cast(str, pkg["license_expression"]),
                 )
             )
         )
@@ -613,8 +620,14 @@ def find_license_from_classifier(classifiers: list[str]) -> list[str]:
 
 
 def select_license_by_source(
-    from_source: FromArg, license_classifier: list[str], license_meta: str
+    from_source: FromArg,
+    license_classifier: list[str],
+    license_meta: str,
+    license_expression: str,
 ) -> set[str]:
+    if license_expression != LICENSE_UNKNOWN:
+        return {license_expression}
+
     license_classifier_set = set(license_classifier) or {LICENSE_UNKNOWN}
     if (
         from_source == FromArg.CLASSIFIER
@@ -635,6 +648,7 @@ def get_output_fields(args: CustomNamespace) -> list[str]:
     if args.from_ == FromArg.ALL:
         output_fields.append("License-Metadata")
         output_fields.append("License-Classifier")
+        output_fields.append("License-Expression")
     else:
         output_fields.append("License")
 
@@ -839,6 +853,7 @@ class FromArg(NoValueEnum):
     META = M = auto()
     CLASSIFIER = C = auto()
     MIXED = MIX = auto()
+    EXPRESSION = EXPR = auto()
     ALL = auto()
 
 

test_piplicenses.py

@@ -212,6 +212,20 @@ def test_from_mixed(self) -> None:
         license_notation_as_classifier = "MIT License"
         self.assertIn(license_notation_as_classifier, license_columns)
 
+    def test_from_expression(self) -> None:
+        from_args = ["--from=expression"]
+        args = self.parser.parse_args(from_args)
+        output_fields = get_output_fields(args)
+        table = create_licenses_table(args, output_fields)
+
+        self.assertIn("License", output_fields)
+
+        license_columns = self._create_license_columns(table, output_fields)
+        license_notation_as_expression = "MIT"
+        # TODO enable assert once a dependency uses 'License-Expression'
+        # TODO (maybe black)
+        # self.assertIn(license_notation_as_expression, license_columns)
+
     def test_from_all(self) -> None:
         from_args = ["--from=all"]
         args = self.parser.parse_args(from_args)
@@ -220,6 +234,7 @@ def test_from_all(self) -> None:
 
         self.assertIn("License-Metadata", output_fields)
         self.assertIn("License-Classifier", output_fields)
+        self.assertIn("License-Expression", output_fields)
 
         index_license_meta = output_fields.index("License-Metadata")
         license_meta = []
@@ -231,6 +246,11 @@ def test_from_all(self) -> None:
         for row in table.rows:
             license_classifier.append(row[index_license_classifier])
 
+        index_license_expression = output_fields.index("License-Expression")
+        license_expression = [
+            row[index_license_expression] for row in table.rows
+        ]
+
         for license_name in ("BSD", "MIT", "Apache 2.0"):
             self.assertIn(license_name, license_meta)
         for license_name in (
@@ -239,6 +259,10 @@ def test_from_all(self) -> None:
             "Apache Software License",
         ):
             self.assertIn(license_name, license_classifier)
+        # TODO enable assert once a dependency uses 'License-Expression'
+        # TODO (maybe black)
+        # for license_name in ("MIT",):
+        #     self.assertIn(license_name, license_expression)
 
     def test_find_license_from_classifier(self) -> None:
         classifiers = ["License :: OSI Approved :: MIT License"]
@@ -270,27 +294,62 @@ def test_select_license_by_source(self) -> None:
         self.assertEqual(
             {"MIT License"},
             select_license_by_source(
-                FromArg.CLASSIFIER, ["MIT License"], "MIT"
+                FromArg.CLASSIFIER, ["MIT License"], "MIT", LICENSE_UNKNOWN
             ),
         )
 
         self.assertEqual(
             {LICENSE_UNKNOWN},
-            select_license_by_source(FromArg.CLASSIFIER, [], "MIT"),
+            select_license_by_source(
+                FromArg.CLASSIFIER, [], "MIT", LICENSE_UNKNOWN
+            ),
         )
 
         self.assertEqual(
             {"MIT License"},
-            select_license_by_source(FromArg.MIXED, ["MIT License"], "MIT"),
+            select_license_by_source(
+                FromArg.MIXED, ["MIT License"], "MIT", LICENSE_UNKNOWN
+            ),
         )
 
         self.assertEqual(
-            {"MIT"}, select_license_by_source(FromArg.MIXED, [], "MIT")
+            {"MIT"},
+            select_license_by_source(
+                FromArg.MIXED, [], "MIT", LICENSE_UNKNOWN
+            ),
         )
         self.assertEqual(
             {"Apache License 2.0"},
             select_license_by_source(
-                FromArg.MIXED, ["Apache License 2.0"], "Apache-2.0"
+                FromArg.MIXED,
+                ["Apache License 2.0"],
+                "Apache-2.0",
+                LICENSE_UNKNOWN,
+            ),
+        )
+
+        self.assertEqual(
+            {"MIT"},
+            select_license_by_source(
+                FromArg.MIXED, [], LICENSE_UNKNOWN, "MIT"
+            ),
+        )
+        self.assertEqual(
+            {"Apache-2.0"},
+            select_license_by_source(
+                FromArg.MIXED,
+                ["Apache License 2.0"],
+                "Apache",
+                "Apache-2.0",
+            ),
+        )
+        self.assertEqual(
+            {"Apache-2.0"},
+            select_license_by_source(
+                FromArg.EXPRESSION,
+                ["Apache License 2.0"],
+                "Apache",
+                "Apache-2.0",
             ),
         )