tests: add Units qml test cases

Add tst_qPrefUnits qml file to test C++ qml connection

Signed-off-by: Jan Iversen <jani@apache.org>

tests/tst_qPrefUnits.qml

@@ -0,0 +1,58 @@
+// SPDX-License-Identifier: GPL-2.0
+import QtQuick 2.6
+import QtTest 1.2
+import org.subsurfacedivelog.mobile 1.0
+
+TestCase {
+	name: "qPrefUnits"
+
+	SsrfUnitPrefs {
+		id: tst
+	}
+
+	SsrfPrefs {
+		id: prefs
+	}
+
+	function test_variables() {
+		var x1 = tst.coordinates_traditional
+		tst.coordinates_traditional = true
+		compare(tst.coordinates_traditional, true)
+
+		var x2 = tst.duration_units
+//TBD		tst.duration_units = ??
+//TBD		compare(tst.duration_units,  ??)
+
+		var x3 = tst.length
+//TBD		tst.=length = ??
+//TBD		compare(tst.length,  ??)
+
+		var x4 = tst.pressure
+//TBD		tst.pressure = ??
+//TBD		compare(tst.pressure, ??)
+
+		var x5 = tst.show_units_table
+		tst.show_units_table = true
+		compare(tst.show_units_table, true)
+
+		var x6 = tst.temperature
+//TBD		tst.temperature = ??
+//TBD		compare(tst.temperature, ??)
+
+		var x7 = tst.unit_system
+		tst.unit_system = "metric" 
+		compare(tst.unit_system, "metric")
+
+		var x8 = tst.vertical_speed_time
+//TBD		tst.vertical_speed_time = ??
+//TBD		compare(tst.vertical_speed_time, ??)
+
+		var x9 = tst.volume
+//TBD		tst.volume = ??
+//TBD		compare(tst.volume, ??)
+
+		var x10 = tst.weight
+//TBD		tst.weight = ??
+//TBD		compare(tst.weight, ??)
+	}
+}