diff --git a/unittest/commands/test_variables.cpp b/unittest/commands/test_variables.cpp
index 6748867b4e..4a0abd1856 100644
--- a/unittest/commands/test_variables.cpp
+++ b/unittest/commands/test_variables.cpp
@@ -337,6 +337,10 @@ TEST_F(VariableTest, Expressions)
     command("variable vec1   vector    \"[-2, 0, 1,2 ,3, 5 ,	7\n]\"");
     command("variable vec2   vector    v_vec1*0.5");
     command("variable vec3   equal     v_vec2[3]");
+    command("variable vec4   vector    '[1, 5, 2.5, -10, -5, 20, 120, 4, 3, 3]'");
+    command("variable sort   vector    sort(v_vec4)");
+    command("variable rsrt   vector    rsort(v_vec4)");
+    command("variable isrt   vector    sort(v_one)");
     variable->set("dummy  index     1 2");
     END_HIDE_OUTPUT();
 
@@ -366,6 +370,8 @@ TEST_F(VariableTest, Expressions)
     EXPECT_THAT(variable->retrieve("vec1"), StrEq("[-2,0,1,2,3,5,7]"));
     EXPECT_THAT(variable->retrieve("vec2"), StrEq("[-1,0,0.5,1,1.5,2.5,3.5]"));
     ASSERT_DOUBLE_EQ(variable->compute_equal("v_vec3"), 0.5);
+    EXPECT_THAT(variable->retrieve("sort"), StrEq("[-10,-5,1,2.5,3,3,4,5,20,120]"));
+    EXPECT_THAT(variable->retrieve("rsrt"), StrEq("[120,20,5,4,3,3,2.5,1,-5,-10]"));
 
     TEST_FAILURE(".*ERROR: Variable six: Invalid thermo keyword 'XXX' in variable formula.*",
                  command("print \"${six}\""););
@@ -377,6 +383,8 @@ TEST_F(VariableTest, Expressions)
                  command("print \"${err2}\""););
     TEST_FAILURE(".*ERROR on proc 0: Variable err3: Invalid power expression in variable formula.*",
                  command("print \"${err3}\""););
+    TEST_FAILURE(".*ERROR: Variable one: Mis-matched special function variable in variable formula.*",
+                 command("print \"${isrt}\""););
 }
 
 TEST_F(VariableTest, Functions)