Fix: es_ES doi() to use standard DOI format

faker/providers/doi/__init__.py

@@ -0,0 +1,20 @@
+from faker.providers import BaseProvider
+
+
+class Provider(BaseProvider):
+    """
+    Provider for Digital Object Identifier (DOI)
+    Source of info: https://en.wikipedia.org/wiki/Digital_object_identifier (English)
+    """
+
+    def doi(self) -> str:
+        """
+        Generate a valid Digital Object Identifier (DOI).
+        Format: 10.{4-9 digits}/{alphanumeric string}
+        Eg: 10.1000/xyz123
+        """
+        prefix = "10"
+        registrant = str(self.generator.random.randint(1000, 99999999))
+        suffix = self.generator.bothify("?#?#?##").lower()
+
+        return f"{prefix}.{registrant}/{suffix}"

tests/providers/test_doi.py

@@ -0,0 +1,26 @@
+import re
+
+from faker import Faker
+
+
+def test_doi():
+    fake = Faker()
+
+    # Test standard DOI
+    doi = fake.doi()
+    assert doi.startswith("10.")
+    # DOI format: 10.{registrant}/{suffix}
+    assert re.match(r"^10\.\d{4,9}/[a-z0-9]+$", doi)
+
+
+def test_doi_es_ES():
+    # Test Spanish locale no longer returns Spanish IDs
+    fake = Faker("es_ES")
+    doi = fake.doi()
+
+    # Should follow DOI format, not Spanish ID format
+    assert doi.startswith("10.")
+    assert re.match(r"^10\.\d{4,9}/[a-z0-9]+$", doi)
+    # Make sure it's not returning Spanish IDs
+    assert not re.match(r"^[XYZ]\d{7}[A-Z]$", doi)  # NIE format
+    assert not re.match(r"^\d{8}[A-Z]$", doi)  # NIF format