diff --git a/tests/test_adif.py b/tests/test_adif.py
index e007ac9..f7501e3 100644
--- a/tests/test_adif.py
+++ b/tests/test_adif.py
@@ -130,7 +130,8 @@ class TestADIF(unittest.TestCase):
         """ Check that records can be written to an ADIF file correctly. """
         records = [{"CALL": "TEST123", "QSO_DATE": "20120402", "TIME_ON": "1234", "FREQ": "145.500", "BAND": "2m", "MODE": "FM", "RST_SENT": "59", "RST_RCVD": "59"},
                    {"CALL": "TEST123", "QSO_DATE": "20130312", "TIME_ON": "0101", "FREQ": "145.750", "BAND": "2m", "MODE": "FM"}]
-        self.adif.write(records, "ADIF.test_write.adi")
+        success = self.adif.write(records, "ADIF.test_write.adi")
+        assert(success)
 
         f = open("ADIF.test_write.adi", 'r')
         text = f.read()
@@ -172,7 +173,8 @@ class TestADIF(unittest.TestCase):
         records = c.fetchall()
         print(records)
 
-        self.adif.write(records, "ADIF.test_write_sqlite3_Row.adi")
+        success = self.adif.write(records, "ADIF.test_write_sqlite3_Row.adi")
+        assert(success)
 
         f = open("ADIF.test_write_sqlite3_Row.adi", 'r')
         text = f.read()
diff --git a/tests/test_cabrillo.py b/tests/test_cabrillo.py
index c632709..9a1ba44 100644
--- a/tests/test_cabrillo.py
+++ b/tests/test_cabrillo.py
@@ -47,7 +47,8 @@ END-OF-LOG:"""
         mycall = "MYCALL"
         mycontest = "MYCONTEST"
         path = "Cabrillo.test_write.log"
-        self.cabrillo.write(records, path, contest=mycontest, mycall=mycall)
+        success = self.cabrillo.write(records, path, contest=mycontest, mycall=mycall)
+        assert(success)
 
         actual = ""
         f = open(path, "r")
diff --git a/tests/test_record_dialog.py b/tests/test_record_dialog.py
index 57e8f6a..8913398 100644
--- a/tests/test_record_dialog.py
+++ b/tests/test_record_dialog.py
@@ -75,6 +75,26 @@ class TestRecordDialog(unittest.TestCase):
         converted = self.record_dialog.convert_frequency(converted, from_unit="kHz", to_unit="MHz")  # Convert from kHz back to MHz. This should give the original frequency.
         assert(float(converted) == float(frequency))
 
+        # Floating-point data type.
+        frequency = 7.140  # In MHz
+        converted = self.record_dialog.convert_frequency(frequency, from_unit="MHz", to_unit="kHz")
+        assert(converted == frequency*1e3)
+
+        # Floating-point data type.
+        frequency = 7.140  # In MHz
+        converted = self.record_dialog.convert_frequency(frequency, from_unit="MHz", to_unit="MHz")
+        assert(converted == frequency)
+
+        # Empty string.
+        frequency = ""
+        converted = self.record_dialog.convert_frequency(frequency, from_unit="MHz", to_unit="kHz")
+        assert(converted == frequency)
+
+        # Not a valid frequency.
+        frequency = "HelloWorld"
+        converted = self.record_dialog.convert_frequency(frequency, from_unit="MHz", to_unit="kHz")
+        assert(converted == frequency)
+
     def test_hamlib_autofill(self):
         """ Check that FREQ, MODE and SUBMODE information can be retrieved from Hamlib's dummy rig (if the Hamlib module exists). """
         if(have_hamlib):