remove no kernels passing in LayerPotentialBase and fix tests

sumpy/qbx.py

@@ -75,16 +75,6 @@ class LayerPotentialBase(KernelComputation, KernelCacheWrapper):
         from pytools import single_valued
         sdr = SourceDerivativeRemover()
         tdr = TargetDerivativeRemover()
-        if source_kernels is None and target_kernels is None:
-            from warnings import warn
-            warn("A list for the second argument of the constructor is deprecated."
-                "Use a single expansion and pass source_kernels and target_kernels",
-                DeprecationWarning, stacklevel=2)
-            source_kernel = single_valued(tdr(exp.kernel) for exp in expansion)
-            base_kernel = sdr(source_kernel)
-            target_kernels = tuple(sdr(exp.kernel) for exp in expansion)
-            source_kernels = (source_kernel,)
-            expansion = expansion[0].copy(kernel=base_kernel)
 
         KernelComputation.__init__(self, ctx=ctx, target_kernels=target_kernels,
                 strength_usage=strength_usage, source_kernels=source_kernels,

test/test_matrixgen.py

@@ -109,24 +109,28 @@ def test_qbx_direct(ctx_factory, factor, lpot_id):
 
     from sumpy.kernel import LaplaceKernel, DirectionalSourceDerivative
     if lpot_id == 1:
-        knl = LaplaceKernel(ndim)
+        base_knl = LaplaceKernel(ndim)
+        knl = base_knl
     elif lpot_id == 2:
-        knl = LaplaceKernel(ndim)
-        knl = DirectionalSourceDerivative(knl, dir_vec_name="dsource_vec")
+        base_knl = LaplaceKernel(ndim)
+        knl = DirectionalSourceDerivative(base_knl, dir_vec_name="dsource_vec")
     else:
         raise ValueError("unknow lpot_id")
 
     from sumpy.expansion.local import LineTaylorLocalExpansion
-    lknl = LineTaylorLocalExpansion(knl, order)
+    expn = LineTaylorLocalExpansion(knl, order)
 
     from sumpy.qbx import LayerPotential
-    lpot = LayerPotential(ctx, [lknl])
+    lpot = LayerPotential(ctx, expansion=expn, source_kernels=(knl,),
+            target_kernels=(base_knl,))
 
     from sumpy.qbx import LayerPotentialMatrixGenerator
-    mat_gen = LayerPotentialMatrixGenerator(ctx, [lknl])
+    mat_gen = LayerPotentialMatrixGenerator(ctx, expansion=expn,
+            source_kernels=(knl,), target_kernels=(base_knl,))
 
     from sumpy.qbx import LayerPotentialMatrixBlockGenerator
-    blk_gen = LayerPotentialMatrixBlockGenerator(ctx, [lknl])
+    blk_gen = LayerPotentialMatrixBlockGenerator(ctx, expansion=expn,
+            source_kernels=(knl,), target_kernels=(base_knl,))
 
     for n in [200, 300, 400]:
         targets, sources, centers, expansion_radii, sigma = \