Report detailed information about invalid requirements

news/12713.feature.rst

@@ -0,0 +1 @@
+Report informative messages about invalid requirements.

src/pip/_internal/req/constructors.py

@@ -206,8 +206,8 @@ def parse_req_from_editable(editable_req: str) -> RequirementParts:
     if name is not None:
         try:
             req: Optional[Requirement] = Requirement(name)
-        except InvalidRequirement:
-            raise InstallationError(f"Invalid requirement: '{name}'")
+        except InvalidRequirement as exc:
+            raise InstallationError(f"Invalid requirement: {name!r}: {exc}")
     else:
         req = None
 
@@ -360,7 +360,7 @@ def with_source(text: str) -> str:
     def _parse_req_string(req_as_string: str) -> Requirement:
         try:
             return get_requirement(req_as_string)
-        except InvalidRequirement:
+        except InvalidRequirement as exc:
             if os.path.sep in req_as_string:
                 add_msg = "It looks like a path."
                 add_msg += deduce_helpful_msg(req_as_string)
@@ -370,7 +370,7 @@ def _parse_req_string(req_as_string: str) -> Requirement:
                 add_msg = "= is not a valid operator. Did you mean == ?"
             else:
                 add_msg = ""
-            msg = with_source(f"Invalid requirement: {req_as_string!r}")
+            msg = with_source(f"Invalid requirement: {req_as_string!r}: {exc}")
             if add_msg:
                 msg += f"\nHint: {add_msg}"
             raise InstallationError(msg)
@@ -429,8 +429,8 @@ def install_req_from_req_string(
 ) -> InstallRequirement:
     try:
         req = get_requirement(req_string)
-    except InvalidRequirement:
-        raise InstallationError(f"Invalid requirement: '{req_string}'")
+    except InvalidRequirement as exc:
+        raise InstallationError(f"Invalid requirement: {req_string!r}: {exc}")
 
     domains_not_allowed = [
         PyPI.file_storage_domain,

tests/unit/test_req.py

@@ -734,7 +734,7 @@ def test_unidentifiable_name(self) -> None:
         with pytest.raises(InstallationError) as e:
             install_req_from_line(test_name)
         err_msg = e.value.args[0]
-        assert f"Invalid requirement: '{test_name}'" == err_msg
+        assert err_msg.startswith(f"Invalid requirement: '{test_name}'")
 
     def test_requirement_file(self) -> None:
         req_file_path = os.path.join(self.tempdir, "test.txt")

tests/unit/test_req_file.py

@@ -269,8 +269,10 @@ def test_error_message(self, line_processor: LineProcessor) -> None:
             )
 
         expected = (
-            "Invalid requirement: 'my-package=1.0' "
-            "(from line 3 of path/requirements.txt)\n"
+            "Invalid requirement: 'my-package=1.0': "
+            "Expected end or semicolon (after name and no valid version specifier)\n"
+            "    my-package=1.0\n"
+            "              ^ (from line 3 of path/requirements.txt)\n"
             "Hint: = is not a valid operator. Did you mean == ?"
         )
         assert str(exc.value) == expected

tests/unit/test_req_install.py

@@ -60,7 +60,12 @@ def test_install_req_from_string_invalid_requirement(self) -> None:
         with pytest.raises(InstallationError) as excinfo:
             install_req_from_req_string("http:/this/is/invalid")
 
-        assert str(excinfo.value) == ("Invalid requirement: 'http:/this/is/invalid'")
+        assert str(excinfo.value) == (
+            "Invalid requirement: 'http:/this/is/invalid': "
+            "Expected end or semicolon (after name and no valid version specifier)\n"
+            "    http:/this/is/invalid\n"
+            "        ^"
+        )
 
     def test_install_req_from_string_without_comes_from(self) -> None:
         """