From 9b0e086bd4c24e0d8fa410171d36e6557b3e82b7 Mon Sep 17 00:00:00 2001
From: Simon Humpohl <simon.humpohl@rwth-aachen.de>
Date: Thu, 1 Dec 2022 15:34:03 +0100
Subject: [PATCH 1/3] Add regression tests

---
 tests/_program/waveforms_tests.py | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/tests/_program/waveforms_tests.py b/tests/_program/waveforms_tests.py
index e4930372b..d84b2c763 100644
--- a/tests/_program/waveforms_tests.py
+++ b/tests/_program/waveforms_tests.py
@@ -555,6 +555,31 @@ def test_validate_input_errors(self):
                                            TableWaveformEntry(-0.2, 0.2, HoldInterpolationStrategy()),
                                            TableWaveformEntry(0.1, 0.2, HoldInterpolationStrategy())])
 
+    def test_validate_input_const_detection(self):
+        constant_table = [TableWaveformEntry(0.0, 2.5, HoldInterpolationStrategy()),
+                          (1.4, 2.5, LinearInterpolationStrategy())]
+        linear_table = [TableWaveformEntry(0.0, 0.0, HoldInterpolationStrategy()),
+                        TableWaveformEntry(1.4, 2.5, LinearInterpolationStrategy())]
+
+        self.assertEqual((1.4, 2.5), TableWaveform._validate_input(constant_table))
+        self.assertEqual(linear_table,
+                         TableWaveform._validate_input(linear_table))
+
+    def test_const_detection_regression(self):
+        # regression test 707
+        from qupulse.pulses import PointPT
+        second_point_pt = PointPT([(0, 'v_0+v_1'),
+                                   ('t_2', 'v_0', 'linear')],
+                                  channel_names=('A',),
+                                  measurements=[('M', 0, 1)])
+        parameters = dict(t=3,
+                          t_2=2,
+                          v_0=1,
+                          v_1=1.4)
+        channel_mapping = {'A': 'A'}
+        wf = second_point_pt.build_waveform(parameters=parameters, channel_mapping=channel_mapping)
+        self.assertIsInstance(wf, TableWaveform)
+
     def test_validate_input_duplicate_removal(self):
         validated = TableWaveform._validate_input([TableWaveformEntry(0.0, 0.2, HoldInterpolationStrategy()),
                                                    TableWaveformEntry(0.1, 0.2, LinearInterpolationStrategy()),

From 578cee9e14db6ff6c95f367a6f6b9733dd49e568 Mon Sep 17 00:00:00 2001
From: Simon Humpohl <simon.humpohl@rwth-aachen.de>
Date: Thu, 1 Dec 2022 15:35:26 +0100
Subject: [PATCH 2/3] Fix wrong interpolation in const detection

---
 qupulse/_program/waveforms.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/qupulse/_program/waveforms.py b/qupulse/_program/waveforms.py
index e9ce8f6f0..a173f3bf3 100644
--- a/qupulse/_program/waveforms.py
+++ b/qupulse/_program/waveforms.py
@@ -298,7 +298,7 @@ def _validate_input(input_waveform_table: Sequence[EntryInInit]) -> Union[Tuple[
             raise ValueError('Negative time values are not allowed.')
 
         # constant_v is None <=> the waveform is constant until up to the current entry
-        constant_v = first_interp.constant_value((previous_t, previous_v), (t, v))
+        constant_v = interp.constant_value((previous_t, previous_v), (t, v))
 
         for next_t, next_v, next_interp in input_iter:
             if next_t < t:

From e117c3a1e612a4206aa2e75ae786d44150b4a6a6 Mon Sep 17 00:00:00 2001
From: Simon Humpohl <simon.humpohl@rwth-aachen.de>
Date: Thu, 1 Dec 2022 15:37:21 +0100
Subject: [PATCH 3/3] Add newspiece

---
 changes.d/707.fix | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 changes.d/707.fix

diff --git a/changes.d/707.fix b/changes.d/707.fix
new file mode 100644
index 000000000..33e9e9f8e
--- /dev/null
+++ b/changes.d/707.fix
@@ -0,0 +1 @@
+Fixed that single segment tables where always interpreted to be constant.