fix null and partial tests

[dehann]

No description provided.

[codecov]

Codecov Report

Merging #1307 (71dbcce) into master (dd390c1) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #1307   +/-   ##
=======================================
  Coverage   10.85%   10.85%           
=======================================
  Files          58       58           
  Lines        4865     4865           
=======================================
  Hits          528      528           
  Misses       4337     4337           

Impacted Files	Coverage Δ
src/ApproxConv.jl	53.42% <100.00%> (ø)

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[dehann]

okay, for the first time in a couple of days the IIF tests are passing again. (cc @Affie )