add tests

test/CDB_DistinctMeasureTest.sql

@@ -0,0 +1,20 @@
+-- a - j add up to 89%, k-m add up to 11%
+WITH a As (
+	SELECT (
+		repeat('a',12) || 
+		repeat('b',11) || 
+		repeat('c',11) || 
+		repeat('d',10) || 
+		repeat('e',10) || 
+		repeat('f',9) || 
+		repeat('g',8) || 
+		repeat('h',7) || 
+		repeat('i',6) || 
+		repeat('j',5) || 
+		repeat('k',4) || 
+		repeat('l',4) || 
+		repeat('m',3)
+		)::text AS x 
+	) 
+
+SELECT CDB_DistinctMeasure(string_to_array(x,null),0.90) from a ;

test/CDB_DistinctMeasureTest_expect

@@ -0,0 +1 @@
+f