Fix initiating duration arrays with numpy array (#39)

* Fix initiating duration arrays with numpy array

* Fix test

Author: anuragm

oqpy/classical_types.py

@@ -374,7 +374,7 @@ def __init__(
             array_base_type = base_type_instance.type_cls()
 
         # Automatically handle Duration array.
-        if base_type is DurationVar and kwargs["init_expression"]:
+        if base_type is DurationVar and kwargs["init_expression"] is not None:
             kwargs["init_expression"] = (make_duration(i) for i in kwargs["init_expression"])
 
         super().__init__(

tests/test_directives.py

@@ -163,8 +163,14 @@ def test_array_declaration():
     multidim = ArrayVar[FloatVar[32], 3, 2](
         name="multiDim", init_expression=[[1.1, 1.2], [2.1, 2.2], [3.1, 3.2]]
     )
+    npinit = ArrayVar(
+        name="npinit",
+        init_expression=np.array([0, 1, 2, 4]) * 1e-9,
+        dimensions=[11],
+        base_type=DurationVar,
+    )
 
-    vars = [b, i, i55, u, x, y, ang, comp, comp55, ang_partial, simple, multidim]
+    vars = [b, i, i55, u, x, y, ang, comp, comp55, ang_partial, simple, multidim, npinit]
 
     prog = oqpy.Program(version=None)
     prog.declare(vars)
@@ -189,6 +195,7 @@ def test_array_declaration():
         array[angle[32], 2] ang_part = {pi, pi / 2};
         array[float[64], 5] no_init;
         array[float[32], 3, 2] multiDim = {{1.1, 1.2}, {2.1, 2.2}, {3.1, 3.2}};
+        array[duration, 11] npinit = {0.0ns, 1.0ns, 2.0ns, 4.0ns};
         i[1] = 0;
         i[idx] = val;
         """