tables/sharedtables/intsets/etc: fix #13496, #13504, #13505; add lots of tests (#13498) [backport]

* fix #13496 handle tombstones
* add test
* more tests
* fix #13504; add SharedTable tests
* fix #https://github.com/nim-lang/Nim/issues/13505 intsets.missingOrExcl silently gave wrong results sometimes
* add test for tintsets

tests/stdlib/tsharedtable.nim

@@ -6,10 +6,84 @@ output: '''
 
 import sharedtables
 
-var table: SharedTable[int, int]
+block:
+  var table: SharedTable[int, int]
 
-init(table)
-table[1] = 10
-assert table.mget(1) == 10
-assert table.mgetOrPut(3, 7) == 7
-assert table.mgetOrPut(3, 99) == 7
+  init(table)
+  table[1] = 10
+  assert table.mget(1) == 10
+  assert table.mgetOrPut(3, 7) == 7
+  assert table.mgetOrPut(3, 99) == 7
+  deinitSharedTable(table)
+
+import sequtils, algorithm
+proc sortedPairs[T](t: T): auto = toSeq(t.pairs).sorted
+template sortedItems(t: untyped): untyped = sorted(toSeq(t))
+
+import tables # refs issue #13504
+
+block: # we use Table as groundtruth, it's well tested elsewhere
+  template testDel(t, t0) =
+    template put2(i) =
+      t[i] = i
+      t0[i] = i
+
+    template add2(i, val) =
+      t.add(i, val)
+      t0.add(i, val)
+
+    template del2(i) =
+      t.del(i)
+      t0.del(i)
+
+    template checkEquals() =
+      doAssert t.len == t0.len
+      for k,v in t0:
+        doAssert t.mgetOrPut(k, -1) == v # sanity check
+        doAssert t.mget(k) == v
+
+    let n = 100
+    let n2 = n*2
+    let n3 = n*3
+    let n4 = n*4
+    let n5 = n*5
+
+    for i in 0..<n:
+      put2(i)
+    for i in 0..<n:
+      if i mod 3 == 0:
+        del2(i)
+    for i in n..<n2:
+      put2(i)
+    for i in 0..<n2:
+      if i mod 7 == 0:
+        del2(i)
+
+    checkEquals()
+
+    for i in n2..<n3:
+      t0[i] = -2
+      doAssert t.mgetOrPut(i, -2) == -2
+      doAssert t.mget(i) == -2
+
+    for i in 0..<n4:
+      let ok = i in t0
+      if not ok: t0[i] = -i
+      doAssert t.hasKeyOrPut(i, -i) == ok
+
+    checkEquals()
+
+    for i in n4..<n5:
+      add2(i, i*10)
+      add2(i, i*11)
+      add2(i, i*12)
+      del2(i)
+      del2(i)
+
+    checkEquals()
+
+  var t: SharedTable[int, int]
+  init(t) # ideally should be auto-init
+  var t0: Table[int, int]
+  testDel(t, t0)
+  deinitSharedTable(t)