diff --git a/src/KIM/kim_init.cpp b/src/KIM/kim_init.cpp
index 511024c7f8..3253c09af7 100644
--- a/src/KIM/kim_init.cpp
+++ b/src/KIM/kim_init.cpp
@@ -365,16 +365,16 @@ void KimInit::do_init(char *model_name, char *user_units, char *model_units, KIM
     KIM_Model_GetNumberOfParameters(pkim, &numberOfParameters);
 
     std::string mesg = "\nThis model has ";
-    if (numberOfParameters)
-    {
+    if (numberOfParameters) {
       KIM_DataType kim_DataType;
       int extent;
       char const *str_name = NULL;
       char const *str_desc = NULL;
 
-      mesg += std::to_string(numberOfParameters);
-      mesg += " mutable parameters. \n";
+      mesg += std::to_string(numberOfParameters) + " mutable parameters. \n";
 
+      // TODO: aligned output is easy to do with fmtlib
+      // https://fmt.dev/latest/syntax.html
       int max_len(0);
       for (int i = 0; i < numberOfParameters; ++i) {
         KIM_Model_GetParameterMetadata(pkim, i, &kim_DataType,
diff --git a/unittest/commands/CMakeLists.txt b/unittest/commands/CMakeLists.txt
index 275e4b973f..f54b10dcb5 100644
--- a/unittest/commands/CMakeLists.txt
+++ b/unittest/commands/CMakeLists.txt
@@ -3,6 +3,10 @@ add_executable(test_simple_commands test_simple_commands.cpp)
 target_link_libraries(test_simple_commands PRIVATE lammps GTest::GMock GTest::GTest)
 add_test(NAME SimpleCommands COMMAND test_simple_commands WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR})
 
+add_executable(test_kim_commands test_kim_commands.cpp)
+target_link_libraries(test_kim_commands PRIVATE lammps GTest::GMock GTest::GTest)
+add_test(NAME KimCommands COMMAND test_kim_commands WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR})
+
 add_executable(test_reset_ids test_reset_ids.cpp)
 target_compile_definitions(test_reset_ids PRIVATE -DTEST_INPUT_FOLDER=${CMAKE_CURRENT_SOURCE_DIR})
 target_link_libraries(test_reset_ids PRIVATE lammps GTest::GMock GTest::GTest)
diff --git a/unittest/commands/test_kim_commands.cpp b/unittest/commands/test_kim_commands.cpp
new file mode 100644
index 0000000000..b261672cbc
--- /dev/null
+++ b/unittest/commands/test_kim_commands.cpp
@@ -0,0 +1,127 @@
+/* ----------------------------------------------------------------------
+   LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
+   http://lammps.sandia.gov, Sandia National Laboratories
+   Steve Plimpton, sjplimp@sandia.gov
+
+   Copyright (2003) Sandia Corporation.  Under the terms of Contract
+   DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government retains
+   certain rights in this software.  This software is distributed under
+   the GNU General Public License.
+
+   See the README file in the top-level LAMMPS directory.
+------------------------------------------------------------------------- */
+
+#include "fmt/format.h"
+#include "info.h"
+#include "input.h"
+#include "lammps.h"
+#include "modify.h"
+#include "utils.h"
+#include "gmock/gmock.h"
+#include "gtest/gtest.h"
+
+#include <cstdlib>
+#include <mpi.h>
+
+// whether to print verbose output (i.e. not capturing LAMMPS screen output).
+bool verbose = false;
+
+using LAMMPS_NS::utils::split_words;
+
+namespace LAMMPS_NS {
+using ::testing::ExitedWithCode;
+using ::testing::MatchesRegex;
+using ::testing::StrEq;
+
+#define TEST_FAILURE(...)                \
+    if (Info::has_exceptions()) {        \
+        ASSERT_ANY_THROW({__VA_ARGS__}); \
+    } else {                             \
+        ASSERT_DEATH({__VA_ARGS__}, ""); \
+    }
+
+class KimCommandsTest : public ::testing::Test {
+protected:
+    LAMMPS *lmp;
+
+    void SetUp() override
+    {
+        const char *args[] = {"KimCommandsTest", "-log", "none", "-echo", "screen", "-nocite"};
+        char **argv        = (char **)args;
+        int argc           = sizeof(args) / sizeof(char *);
+        if (!verbose) ::testing::internal::CaptureStdout();
+        lmp = new LAMMPS(argc, argv, MPI_COMM_WORLD);
+        if (!verbose) ::testing::internal::GetCapturedStdout();
+    }
+
+    void TearDown() override
+    {
+        if (!verbose) ::testing::internal::CaptureStdout();
+        delete lmp;
+        if (!verbose) ::testing::internal::GetCapturedStdout();
+    }
+};
+
+TEST_F(KimCommandsTest, kim_init)
+{
+    if (!LAMMPS::is_installed_pkg("KIM")) GTEST_SKIP();
+
+    ::testing::internal::CaptureStdout();
+    lmp->input->one("kim_init LennardJones_Ar real");
+    ::testing::internal::GetCapturedStdout();
+
+    int ifix = lmp->modify->find_fix("KIM_MODEL_STORE");
+    ASSERT_GE(ifix, 0);
+
+    ::testing::internal::CaptureStdout();
+    TEST_FAILURE(lmp->input->one("kim_init"););
+    auto mesg = ::testing::internal::GetCapturedStdout();
+    ASSERT_THAT(mesg, MatchesRegex(".*ERROR: Illegal kim_init command.*"));
+
+    ::testing::internal::CaptureStdout();
+    TEST_FAILURE(lmp->input->one("kim_init Unknown_Model real"););
+    mesg = ::testing::internal::GetCapturedStdout();
+    ASSERT_THAT(mesg, MatchesRegex(".*ERROR: KIM Model name not found.*"));
+}
+
+TEST_F(KimCommandsTest, kim_interactions_ar)
+{
+    if (!LAMMPS::is_installed_pkg("KIM")) GTEST_SKIP();
+
+    ::testing::internal::CaptureStdout();
+    lmp->input->one("kim_init LennardJones_Ar real");
+    lmp->input->one("lattice fcc 4.4300");
+    lmp->input->one("region box block 0 10 0 10 0 10");
+    lmp->input->one("create_box 1 box");
+    lmp->input->one("create_atoms 1 box");
+    lmp->input->one("kim_interactions Ar");
+    lmp->input->one("mass 1 39.95");
+    ::testing::internal::GetCapturedStdout();
+
+    int ifix = lmp->modify->find_fix("KIM_MODEL_STORE");
+    ASSERT_GE(ifix, 0);
+}
+
+} // namespace LAMMPS_NS
+
+int main(int argc, char **argv)
+{
+    MPI_Init(&argc, &argv);
+    ::testing::InitGoogleMock(&argc, argv);
+
+    // handle arguments passed via environment variable
+    if (const char *var = getenv("TEST_ARGS")) {
+        std::vector<std::string> env = split_words(var);
+        for (auto arg : env) {
+            if (arg == "-v") {
+                verbose = true;
+            }
+        }
+    }
+
+    if ((argc > 1) && (strcmp(argv[1], "-v") == 0)) verbose = true;
+
+    int rv = RUN_ALL_TESTS();
+    MPI_Finalize();
+    return rv;
+}