test: which: check assumptions

Author: scivision

+stdlib/which.m

@@ -27,7 +27,7 @@
   return
 end
 
-%  relative directory component, but path was not a file
+%  relative directory component, but path was not an executable file
 if ~strcmp(stdlib.filename(cmd), cmd)
   return
 end

test/TestWhich.m

@@ -39,7 +39,9 @@ function test_which_absolute(tc, mexe)
 end
 
 tc.assumeThat(r, matlab.unittest.constraints.IsFile)
+tc.assumeTrue(stdlib.is_exe(r))
 
+tc.verifyEqual(stdlib.which(r), r)
 tc.verifyEqual(stdlib.which(mexe), r)
 
 end