Unit tests for vecreg

Primarily testing the new --premat / --postmat options (see fdt!23 (merged))

unit_tests/fdt/vecreg/feedsRun

@@ -34,7 +34,7 @@ def main():
     # create a copy of the diff2std warp
     # which does not encode the diff2std
     # affine
-    diff2std_warp_no_premat = outdir/'diff2std_no_pm_warp.nii.gz'
+    diff2std_warp_no_premat = outdir/'diff2std_warp_no_premat.nii.gz'
     convertwarp(diff2std_warp_no_premat, std,
                 warp1=diff2std_warp,
                 premat=std2diff,
@@ -56,10 +56,35 @@ def main():
            warpfield=diff2std_warp_no_premat,
            premat=diff2std)
 
+    # compare the result
     dyads1 = Image(dyads_std).data
     dyads2 = Image(dyads_std_with_premat).data
-    diff = cmpVectorArrays(dyads1, dyads2)
-    assert np.isclose(diff, 0), diff
+    diff   = cmpVectorArrays(dyads1, dyads2)
+    assert np.isclose(diff, 0, atol=1e-4), diff
+
+    # Create a nonsense warp field with a postmat
+    diff2std_warp_postmat = outdir/'diff2std_warp_postmat.nii.gz'
+    convertwarp(diff2std_warp_postmat, std,
+                warp1=diff2std_warp_no_premat,
+                premat=diff2std,
+                postmat=std2diff)
+
+    # Warp dyads with the nonsense warp
+    dyads_postmat1 = outdir/'dyads_postmat1.nii.gz'
+    vecreg(dyads, dyads_postmat1, std,
+           warpfield=diff2std_warp_postmat)
+
+    # And with the original warp+premat+postmat
+    dyads_postmat2 = outdir/'dyads_postmat2.nii.gz'
+    vecreg(dyads, dyads_postmat2, std,
+           warpfield=diff2std_warp_no_premat,
+           premat=diff2std, postmat=std2diff)
+
+    # And check that the results are equivalent
+    dyads1 = Image(dyads_postmat1).data
+    dyads2 = Image(dyads_postmat2).data
+    diff   = cmpVectorArrays(dyads1, dyads2)
+    assert np.isclose(diff, 0, atol=1e-4), diff
 
 
 if __name__ == '__main__':