diff --git a/src/fixate/ui_cmdline/cmd_line.py b/src/fixate/ui_cmdline/cmd_line.py
index fa6e89df..9a57d426 100644
--- a/src/fixate/ui_cmdline/cmd_line.py
+++ b/src/fixate/ui_cmdline/cmd_line.py
@@ -2,6 +2,7 @@
 import sys
 import time
 import textwrap
+from math import isclose
 from queue import Empty
 from pubsub import pub
 from fixate.ui_cmdline.kbhit import KBHit
@@ -300,7 +301,13 @@ def round_to_3_sig_figures(chk):
     for element in ["_min", "_max", "test_val", "nominal", "tol"]:
         ret_dict[element] = getattr(chk, element, None)
         try:
-            ret_dict[element] = "{:.3g}".format(ret_dict[element])
+            new = "{:.3g}".format(ret_dict[element])
+            if isinstance(ret_dict[element], int):
+                new_check = int(new)
+            elif isinstance(ret_dict[element], float):
+                new_check = float(new)
+            assert isclose(ret_dict[element], new_check, abs_tol=1e-2)
+            ret_dict[element] = new
         except:
             pass
     return ret_dict
diff --git a/test/core/test_checks.py b/test/core/test_checks.py
new file mode 100644
index 00000000..5533a676
--- /dev/null
+++ b/test/core/test_checks.py
@@ -0,0 +1,118 @@
+import pytest
+import time
+from fixate.core.checks import chk_smaller
+from fixate.core.exceptions import CheckFail
+from datetime import datetime, timedelta
+from fixate.core.checks import CheckClass, chk_in_range, _in_range
+from fixate.ui_cmdline.cmd_line import _print_comparisons
+
+
+def test_time_struct_check_true():
+    t = time.localtime(1545925765)
+    chk = chk_in_range(t, time.localtime(1545925760), time.localtime(1545925777), "Time is in range")
+    assert chk
+
+
+def test_time_struct_check_false():
+    with pytest.raises(CheckFail):
+        t = time.localtime(1554452763)
+        chk = chk_in_range(t, time.localtime(1545925760), time.localtime(1545925777), "Time is NOT in range")
+
+
+def test_datetime_struct_check_true():
+    t_min = datetime.now()
+    time.sleep(1)
+    t = datetime.now()
+    time.sleep(1)
+    t_max = datetime.now()
+    chk = chk_in_range(t, t_min, t_max, "DateTime is in range")
+    assert chk
+
+
+def test_datetime_struct_check_false():
+    with pytest.raises(CheckFail):
+        t_min = datetime.now()
+        time.sleep(1)
+        t_max = datetime.now()
+        time.sleep(1)
+        t = datetime.now()
+        chk = chk_in_range(t, t_min, t_max, "DateTime is not in range")
+        assert chk
+
+
+def test_check_formatting(capsys):
+    '''
+    Check output of checks for ints, datetime objects and floats
+    :param capsys:
+    :return:
+    '''
+    chk1 = CheckClass(_min=2, _max=4, test_val=3, target=_in_range)
+    date_obj = datetime(2019, 1, 1, 0, 0)
+    chk2 = CheckClass(_min=date_obj - timedelta(seconds=2), _max=date_obj + timedelta(seconds=2), test_val=date_obj, target=_in_range)
+    chk3 = CheckClass(_min=2.12345, _max=3.12345, test_val=2.9876543210, target=_in_range)
+
+    _print_comparisons(True, chk1, 1, None)
+    captured = capsys.readouterr()
+    assert captured.out.strip('\n') == "Check 1: PASS when comparing 3 in range 2 - 4 :"
+    _print_comparisons(True, chk2, 2, None)
+    captured = capsys.readouterr()
+    output = "Check 2: PASS when comparing 2019-01-01 00:00:00 in range {} - {} :".format(date_obj - timedelta(seconds=2),
+                                                                                 date_obj + timedelta(seconds=2))
+    expected = captured.out.strip('\n').replace('\n', ' ')
+    assert output == expected
+    _print_comparisons(True, chk3, 3, None)
+    captured = capsys.readouterr()
+    assert captured.out.strip('\n') == "Check 3: PASS when comparing 2.99 in range 2.12 - 3.12 :"
+
+
+def test_check_smaller():
+    assert chk_smaller(1, 2)
+    with pytest.raises(CheckFail):
+        chk_smaller(2, 1)
+
+
+def test_check_smaller_datetime_now():
+    now = datetime.now()
+    time.sleep(0.1)
+    now_plus = datetime.now()
+    assert chk_smaller(now, now_plus)
+    with pytest.raises(CheckFail):
+        chk_smaller(now_plus, now)
+
+
+def test_check_smaller_datetime_time():
+    now = datetime.now()
+    now = datetime.time(now)
+    time.sleep(0.001)
+    now_plus = datetime.now()
+    now_plus = datetime.time(now_plus)
+    assert chk_smaller(now, now_plus)
+    with pytest.raises(CheckFail):
+        chk_smaller(now_plus, now)
+
+
+def test_check_smaller_datetime_milli():
+    now = datetime(2000, 1, 1, 1, 1, 1, 1)
+    now_minus = datetime(2000, 1, 1, 1, 1, 1, 0)
+    assert chk_smaller(now_minus, now)
+    with pytest.raises(CheckFail):
+        chk_smaller(now, now_minus)
+
+
+def test_check_smaller_time():
+    now = time.time()
+    time.sleep(1)
+    now_plus = time.time()
+    assert chk_smaller(now, now_plus)
+    with pytest.raises(CheckFail):
+        chk_smaller(now_plus, now)
+
+
+def test_check_smaller_localtime():
+    now = time.localtime()
+    time.sleep(1)
+    now_plus = time.localtime()
+    assert chk_smaller(now, now_plus)
+    with pytest.raises(CheckFail):
+        chk_smaller(now_plus, now)
+