Add linearity check to consistency_check

nifty5/extra.py

@@ -19,6 +19,7 @@ import numpy as np
 
 from .field import Field
 from .linearization import Linearization
+from .operators.linear_operator import LinearOperator
 from .sugar import from_random
 
 __all__ = ["consistency_check", "check_value_gradient_consistency",
@@ -62,8 +63,20 @@ def _full_implementation(op, domain_dtype, target_dtype, atol, rtol):
     _inverse_implementation(op, domain_dtype, target_dtype, atol, rtol)
 
 
+def _check_linearity(op, domain_dtype, atol, rtol):
+    fld1 = from_random("normal", op.domain, dtype=domain_dtype)
+    fld2 = from_random("normal", op.domain, dtype=domain_dtype)
+    alpha = np.random.random()
+    val1 = op(alpha*fld1+fld2)
+    val2 = alpha*op(fld1)+op(fld2)
+    _assert_allclose(val1, val2, atol=atol, rtol=rtol)
+
+
 def consistency_check(op, domain_dtype=np.float64, target_dtype=np.float64,
                       atol=0, rtol=1e-7):
+    if not isinstance(op, LinearOperator):
+        raise TypeError('This test tests only linear operators.')
+    _check_linearity(op, domain_dtype, atol, rtol)
     _full_implementation(op, domain_dtype, target_dtype, atol, rtol)
     _full_implementation(op.adjoint, target_dtype, domain_dtype, atol, rtol)
     _full_implementation(op.inverse, target_dtype, domain_dtype, atol, rtol)