XDIWriter now includes the mono d-spacing as metadata.

Note: it uses the energy_positioner's ``d_spacing`` component. This
doesn't necessariy save the real mono; future work will need to be
done to make sure the energy device's ``d_spacing`` component is
actually the d-spacing of the mono.

src/conftest.py

@@ -32,6 +32,7 @@
 from haven.instrument.dxp import DxpDetector
 from haven.instrument.dxp import add_mcas as add_dxp_mcas
 from haven.instrument.ion_chamber import IonChamber
+from haven.instrument.monochromator import Monochromator
 from haven.instrument.robot import Robot
 from haven.instrument.shutter import Shutter
 from haven.instrument.slits import ApertureSlits, BladeSlits
@@ -274,6 +275,13 @@ def aerotech_flyer(aerotech):
     yield flyer
 
 
+@pytest.fixture()
+def mono(sim_registry):
+    mono = instantiate_fake_device(Monochromator, name="monochromator")
+    sim_registry.register(mono)
+    yield mono
+
+
 @pytest.fixture()
 def aps(sim_registry):
     aps = instantiate_fake_device(ApsMachine, name="APS")

src/haven/plans/energy_scan.py

@@ -130,12 +130,21 @@ def energy_scan(
     scan_args = [(motor, energies) for motor in energy_positioners]
     scan_args += [(motor, exposure) for motor in time_positioners]
     scan_args = [item for items in scan_args for item in items]
-    # Do the actual scan
+    # Add some extra metadata
     config = load_config()
+    md_ = {"edge": E0_str, "E0": E0}
+    for positioner in energy_positioners:
+        try:
+            md_["d_spacing"] = positioner.d_spacing.get()
+        except AttributeError:
+            continue
+        else:
+            break
+    # Do the actual scan
     yield from bp.list_scan(
         real_detectors,
         *scan_args,
-        md=ChainMap(md, {"edge": E0_str, "E0": E0}, config),
+        md=ChainMap(md, md_, config),
     )
 
 

src/haven/tests/test_energy_xafs_scan.py

@@ -96,6 +96,22 @@ def test_raises_on_empty_positioners(RE, energies):
         RE(energy_scan(energies, energy_positioners=[]))
 
 
+def test_saves_dspacing(mono, energies, I0, It):
+    """Does the mono's d-spacing get added to metadata."""
+    # Prepare the messages from the plan
+    mono.d_spacing._readback = 1.5418
+    msgs = list(energy_scan(energies, detectors=[It], energy_positioners = [mono], time_positioners=[It.exposure_time]))
+    # Find the metadata written by the plan
+    for msg in msgs:
+        if msg.command == "open_run":
+            md = msg.kwargs
+            break
+    else:
+        raise RuntimeError("No open run message found")
+    # Check for the dspacing of the mono in the metadata
+    assert md['d_spacing'] == 1.5418
+
+
 def test_single_range(mono_motor, exposure_motor, I0):
     E0 = 10000
     expected_energies = np.arange(9990, 10001, step=1)

src/haven/tests/test_xdi_writer.py

@@ -111,6 +111,7 @@
 start_doc = {
     "versions": {"bluesky": "1.8.3", "ophyd": "1.6.4"},
     "detectors": ["I0", "It"],
+    "d_spacing": 3.,
     "motors": ["energy", "exposure"],
     "edge": "Ni_K",
     "facility": {
@@ -202,7 +203,7 @@ def test_required_headers(writer):
     assert "# Column.1: energy" in xdi_output
     assert "# Element.symbol: Ni" in xdi_output
     assert "# Element.edge: K" in xdi_output
-    # assert "# Mono.d_spacing: 3" in xdi_output  # Not implemented yet
+    assert "# Mono.d_spacing: 3" in xdi_output  # Not implemented yet
     assert "# -------------" in xdi_output
 
 

src/haven/xdi_writer.py

@@ -232,6 +232,14 @@ def write_header(self, doc):
         else:
             fd.write(f"# Element.symbol: {elem}\n")
             fd.write(f"# Element.edge: {edge}\n")
+        # Monochromator information
+        try:
+            d_spacing = doc['d_spacing']
+        except KeyError:
+            pass
+        else:
+            fd.write(f"# Mono.d_spacing: {d_spacing}\n")
+        # Facility information
         now = self.start_time
         fd.write(f"# Scan.start_time: {now.strftime('%Y-%m-%d %H:%M:%S%z')}\n")
         md_paths = [