Plumbing for next gen measures dummy data

ehrql/measures/measures.py

@@ -295,6 +295,20 @@ def configure_dummy_data(self, *, population_size):
         ```
         """
         self.dummy_data_config.population_size = population_size
+        self.dummy_data_config.next_gen = False
+
+    def configure_next_gen_dummy_data(self, *, population_size):
+        """
+        Configure the dummy data to be generated, using the 'next generation' dummy data.
+
+        Note that this feature is currently experimental and is not fully documented yet.
+
+        ```py
+        measures.configure_next_gen_dummy_data(population_size=10000)
+        ```
+        """
+        self.dummy_data_config.population_size = population_size
+        self.dummy_data_config.next_gen = True
 
     def configure_disclosure_control(self, *, enabled=True):
         """

tests/integration/test_main.py

@@ -114,6 +114,34 @@ def test_generate_measures_dummy_data_generated(tmp_path, disclosure_control_ena
     )
 
 
+@pytest.mark.parametrize("disclosure_control_enabled", [False, True])
+def test_generate_measures_next_gen_dummy_data_generated(
+    tmp_path, disclosure_control_enabled
+):
+    measure_definitions = tmp_path / "measures.py"
+    measure_definitions.write_text(
+        MEASURE_DEFINITIONS
+        + "\nmeasures.configure_next_gen_dummy_data(population_size=10)"
+    )
+    output_file = tmp_path / "output.csv"
+
+    generate_measures(
+        measure_definitions,
+        output_file,
+        # Defaults
+        dsn=None,
+        backend_class=None,
+        query_engine_class=None,
+        dummy_tables_path=None,
+        dummy_data_file=None,
+        environ={},
+        user_args=(),
+    )
+    assert output_file.read_text().startswith(
+        "measure,interval_start,interval_end,ratio,numerator,denominator,sex"
+    )
+
+
 @pytest.mark.parametrize("disclosure_control_enabled", [False, True])
 def test_generate_measures_dummy_data_supplied(tmp_path, disclosure_control_enabled):
     measure_definitions = tmp_path / "measures.py"

tests/unit/measures/test_dummy_data.py

@@ -1,5 +1,7 @@
 from datetime import date
 
+import pytest
+
 from ehrql import years
 from ehrql.measures import INTERVAL, DummyMeasuresDataGenerator, Measures
 from ehrql.tables import Constraint, EventFrame, PatientFrame, Series, table
@@ -87,7 +89,11 @@ def test_population_is_nonzero_when_no_groups():
     assert generator.generator.population_size > 0
 
 
-def test_configured_population_size():
+@pytest.mark.parametrize(
+    "configure_dummy_data_method",
+    ["configure_dummy_data", "configure_next_gen_dummy_data"],
+)
+def test_configured_population_size(configure_dummy_data_method):
     measures = Measures()
     measures.define_measure(
         "had_event",
@@ -96,7 +102,7 @@ def test_configured_population_size():
         intervals=years(1).starting_on("2020-01-01"),
     )
 
-    measures.configure_dummy_data(population_size=10)
+    getattr(measures, configure_dummy_data_method)(population_size=10)
 
     generator = DummyMeasuresDataGenerator(measures, measures.dummy_data_config)
     assert generator.generator.population_size == 10