move rest of tests to testament (#16140)

* move rest of tests to testament
* Update tests/stdlib/tsums.nim

tests/stdlib/tsums.nim

@@ -0,0 +1,22 @@
+import std/sums
+from math import pow
+
+var epsilon = 1.0
+while 1.0 + epsilon != 1.0:
+  epsilon /= 2.0
+let data = @[1.0, epsilon, -epsilon]
+assert sumKbn(data) == 1.0
+# assert sumPairs(data) != 1.0 # known to fail in 64 bits
+assert (1.0 + epsilon) - epsilon != 1.0
+
+var tc1: seq[float]
+for n in 1 .. 1000:
+  tc1.add 1.0 / n.float
+assert sumKbn(tc1) == 7.485470860550345
+assert sumPairs(tc1) == 7.485470860550345
+
+var tc2: seq[float]
+for n in 1 .. 1000:
+  tc2.add pow(-1.0, n.float) / n.float
+assert sumKbn(tc2) == -0.6926474305598203
+assert sumPairs(tc2) == -0.6926474305598204