Use ranges to specify call count

src/spectator/matchers/receive_matcher.cr

@@ -3,7 +3,9 @@ require "./standard_matcher"
 
 module Spectator::Matchers
   struct ReceiveMatcher < StandardMatcher
-    def initialize(@expected : TestExpression(Symbol), @count : Int32? = nil)
+    alias Range = ::Range(Int32, Int32) | ::Range(Nil, Int32) | ::Range(Int32, Nil)
+
+    def initialize(@expected : TestExpression(Symbol), @range : Range? = nil)
     end
 
     def description : String
@@ -13,8 +15,8 @@ module Spectator::Matchers
     def match?(actual : TestExpression(T)) : Bool forall T
       double = actual.value.as(Mocks::Double)
       calls = double.spectator_stub_calls(@expected.value)
-      if (count = @count)
-        count == calls.size
+      if (range = @range)
+        range.includes?(calls.size)
       else
         !calls.empty?
       end
@@ -27,10 +29,39 @@ module Spectator::Matchers
     def values(actual : TestExpression(T)) forall T
       double = actual.value.as(Mocks::Double)
       calls = double.spectator_stub_calls(@expected.value)
+      range = @range
       {
-        expected: "#{@count ? "#{@count} time(s)" : "At least once"} with any arguments",
+        expected: "#{range ? "#{humanize_range(range)} time(s)" : "At least once"} with any arguments",
         received: "#{calls.size} time(s) with any arguments",
       }
     end
+
+    def once
+      ReceiveMatcher.new(@expected, (1..1))
+    end
+
+    def twice
+      ReceiveMatcher.new(@expected, (2..2))
+    end
+
+    def humanize_range(range : Range)
+      if (min = range.begin)
+        if (max = range.end)
+          if min == max
+            min
+          else
+            "#{min} to #{max}"
+          end
+        else
+          "At least #{min}"
+        end
+      else
+        if (max = range.end)
+          "At most #{max}"
+        else
+          raise "Unexpected endless range"
+        end
+      end
+    end
   end
 end