From 0fc564bdc9ae6db768f2e3b5522e98b61e50280f Mon Sep 17 00:00:00 2001
From: Ian Hincks <ian.hincks@ibm.com>
Date: Fri, 26 Jan 2024 01:36:55 -0500
Subject: [PATCH] Add BindingsArray as allowed input type to
 BindingsArray.coerce() (#11645)

---
 qiskit/primitives/containers/bindings_array.py  |  2 ++
 .../containers/test_bindings_array.py           | 17 +++++++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/qiskit/primitives/containers/bindings_array.py b/qiskit/primitives/containers/bindings_array.py
index 05d35e75be60..036465369ba0 100644
--- a/qiskit/primitives/containers/bindings_array.py
+++ b/qiskit/primitives/containers/bindings_array.py
@@ -270,6 +270,8 @@ def coerce(cls, bindings_array: BindingsArrayLike) -> BindingsArray:
             bindings_array = cls(bindings_array)
         elif isinstance(bindings_array, Mapping):
             bindings_array = cls(kwvals=bindings_array)
+        elif isinstance(bindings_array, BindingsArray):
+            return bindings_array
         else:
             raise TypeError(f"Unsupported type {type(bindings_array)} is given.")
         return bindings_array
diff --git a/test/python/primitives/containers/test_bindings_array.py b/test/python/primitives/containers/test_bindings_array.py
index dabe4b45a712..4affdcd41102 100644
--- a/test/python/primitives/containers/test_bindings_array.py
+++ b/test/python/primitives/containers/test_bindings_array.py
@@ -431,3 +431,20 @@ def test_simple_vals(self):
             self.assertEqual(ba.shape, (1,))
             self.assertEqual(len(ba.vals), 1)
             np.testing.assert_allclose(ba.vals[0], [[1, 2, 3]])
+
+    def test_coerce(self):
+        """Test the coerce() method."""
+        # BindingsArray passthrough
+        arg = BindingsArray({"a": np.linspace(0, 1, 5)})
+        ba = BindingsArray.coerce(arg)
+        self.assertEqual(ba, arg)
+
+        # dict-valued input
+        arg = {"a": np.linspace(0, 1, 5)}
+        ba = BindingsArray.coerce(arg)
+        self.assertEqual(ba.num_parameters, 1)
+
+        # None-valued input
+        arg = None
+        ba = BindingsArray.coerce(None)
+        self.assertEqual(ba.num_parameters, 0)