diff --git a/unittest/commands/test_delete_atoms.cpp b/unittest/commands/test_delete_atoms.cpp
index d7c37d7311..3812163a7a 100644
--- a/unittest/commands/test_delete_atoms.cpp
+++ b/unittest/commands/test_delete_atoms.cpp
@@ -70,8 +70,10 @@ protected:
         command("region left block -2.0 -1.0 INF INF INF INF");
         command("region right block 0.5  2.0 INF INF INF INF");
         command("region top block INF INF -2.0 -1.0 INF INF");
+        command("region bottom block INF INF 0.0 4.0 INF INF");
         command("set region left type 2");
         command("set region right type 3");
+        command("group bottom region bottom");
         command("group top region top");
         END_HIDE_OUTPUT();
     }
@@ -109,19 +111,51 @@ TEST_F(DeleteAtomsTest, Simple)
     ASSERT_EQ(atom->natoms, 392);
 
     HIDE_OUTPUT([&] {
-        command("delete_atoms porosity all right 0.5 43252");
+        command("delete_atoms partial fraction 0.5 yes all right 43252");
     });
-    ASSERT_EQ(atom->natoms, 362);
+    ASSERT_EQ(atom->natoms, 364);
 
     HIDE_OUTPUT([&] {
         command("variable checker atom sin(4*PI*x/lx)*sin(4*PI*y/ly)*sin(4*PI*z/lz)>0");
         command("delete_atoms variable checker");
     });
-    ASSERT_EQ(atom->natoms, 177);
+    ASSERT_EQ(atom->natoms, 178);
+
+    HIDE_OUTPUT([&] {
+        command("delete_atoms partial count 3 no bottom right 443252");
+    });
+    ASSERT_EQ(atom->natoms, 175);
+
+    HIDE_OUTPUT([&] {
+        command("delete_atoms partial count 50 no all NULL 434325");
+    });
+    ASSERT_EQ(atom->natoms, 125);
+
+    HIDE_OUTPUT([&] {
+        command("delete_atoms partial fraction 0.2 no all NULL 34325");
+    });
+    ASSERT_EQ(atom->natoms, 104);
+
+    HIDE_OUTPUT([&] {
+        command("delete_atoms partial count 50 no bottom right 77325");
+    });
+    ASSERT_EQ(atom->natoms, 102);
 
     TEST_FAILURE(".*ERROR: Illegal delete_atoms command: missing argument.*",
                  command("delete_atoms"););
     TEST_FAILURE(".*ERROR: Unknown delete_atoms sub-command: xxx.*", command("delete_atoms xxx"););
+    TEST_FAILURE(".*ERROR: The delete_atoms 'porosity' keyword has been removed.*",
+                 command("delete_atoms porosity 0.5 all right 4325234"););
+    TEST_FAILURE(".*ERROR: Illegal delete_atoms partial command: missing argument.*",
+                 command("delete_atoms partial count 50 bottom right 77325"););
+    TEST_FAILURE(".*ERROR: Illegal delete_atoms partial command: missing argument.*",
+                 command("delete_atoms partial fraction 0.4 bottom right 77325"););
+    TEST_FAILURE(".*ERROR: Delete_atoms partial count has invalid value: -5.*",
+                 command("delete_atoms partial count -5 no bottom right 77325"););
+    TEST_FAILURE(".*ERROR: Delete_atoms count of 5 exceeds number of eligible atoms 0.*",
+                 command("delete_atoms partial count 5 yes bottom right 77325"););
+    TEST_FAILURE(".*ERROR: Delete_atoms partial fraction has invalid value: -0.4.*",
+                 command("delete_atoms partial fraction -0.4 no bottom right 77325"););
 }
 } // namespace LAMMPS_NS