@Test
    public void testReverseProximity() {
        assertMetrics("unweightedProximity:0.33",  "a b","b a");
        assertMetrics("unweightedProximity:0.62",  "a b c","c a b");
        assertMetrics("unweightedProximity:0.585", "y a b c","c x a b");
        assertMetrics("unweightedProximity:0.33",  "a b c","c b a");
        assertMetrics("unweightedProximity:0.6875","a b c d e","a b d c e");
        assertMetrics("unweightedProximity:0.9275","a b c d e","a b x c d e");
    }
Calculated the same way as weight
searchlib/src/test/java/com/yahoo/searchlib/ranking/features/fieldmatch/test/FieldMatchMetricsTestCase.java