Turn some test outputs into actual tests

lib/pure/collections/critbits.nim

@@ -286,6 +286,8 @@ proc `$`*[T](c: CritBitTree[T]): string =
     result.add("}")
 
 when isMainModule:
+  import sequtils
+
   var r: CritBitTree[void]
   r.incl "abc"
   r.incl "xyz"
@@ -295,12 +297,8 @@ when isMainModule:
 
   doAssert r.contains"def"
 
-  when not defined(testing):
-    #r.del "def"
+  r.excl "def"
 
-    for w in r.items:
-      echo w
-
-    for w in r.itemsWithPrefix("de"):
-      echo w
+  assert toSeq(r.items) == @["abc", "definition", "prefix", "xyz"]
 
+  assert toSeq(r.itemsWithPrefix("de")) == @["definition"]

lib/pure/collections/intsets.nim

@@ -197,15 +197,22 @@ proc empty*(s: IntSet): bool {.inline, deprecated.} =
   ## worked reliably and so is deprecated.
   result = s.counter == 0
 
-when not defined(testing) and isMainModule:
+when isMainModule:
+  import sequtils, algorithm
+
   var x = initIntSet()
   x.incl(1)
   x.incl(2)
   x.incl(7)
   x.incl(1056)
-  for e in items(x): echo e
 
-  var y: TIntSet
+  var xs = toSeq(items(x))
+  xs.sort(cmp[int])
+  assert xs == @[1, 2, 7, 1056]
+
+  var y: IntSet
   assign(y, x)
-  for e in items(y): echo e
+  var ys = toSeq(items(y))
+  ys.sort(cmp[int])
+  assert ys == @[1, 2, 7, 1056]
 

lib/pure/collections/sequtils.nim

@@ -492,10 +492,8 @@ when isMainModule:
 
   block: # filter iterator test
     let numbers = @[1, 4, 5, 8, 9, 7, 4]
-    for n in filter(numbers, proc (x: int): bool = x mod 2 == 0):
-      when not defined(testing):
-        echo($n)
-    # echoes 4, 8, 4 in separate lines
+    assert toSeq(filter(numbers, proc (x: int): bool = x mod 2 == 0)) ==
+      @[4, 8, 4]
 
   block: # keepIf test
     var floats = @[13.0, 12.5, 5.8, 2.0, 6.1, 9.9, 10.1]