Add less-than-equal-to matcher

src/spectator/matchers/be_comparison.cr

@@ -19,8 +19,8 @@ module Spectator::Matchers
     # ```
     # expect(0).to be <= 1
     # ```
-    def <=(other : ExpectedType) forall ExpectedType
-      raise NotImplementedError.new("be <=")
+    def <=(expected : ExpectedType) forall ExpectedType
+      LessThanEqualMatcher.new(expected)
     end
 
     # Creates a matcher that checks if a value is greater than an expected value.

src/spectator/matchers/less_than_equal_matcher.cr

@@ -0,0 +1,25 @@
+require "./value_matcher"
+
+module Spectator::Matchers
+  # Matcher that tests whether one value is less than or equal to another.
+  # The values are compared with the `<=` operator.
+  struct LessThanEqualMatcher(ExpectedType) < ValueMatcher(ExpectedType)
+    # Determines whether the matcher is satisfied with the value given to it.
+    # True is returned if the match was successful, false otherwise.
+    def match?(partial : Expectations::ValueExpectationPartial(ActualType)) : Bool forall ActualType
+      partial.actual <= expected
+    end
+
+    # Describes the condition that satisfies the matcher.
+    # This is informational and displayed to the end-user.
+    def message(partial : Expectations::ValueExpectationPartial(ActualType)) : String forall ActualType
+      "Expected #{partial.label} to be less than or equal to #{label} (using <=)"
+    end
+
+    # Describes the condition that won't satsify the matcher.
+    # This is informational and displayed to the end-user.
+    def negated_message(partial : Expectations::ValueExpectationPartial(ActualType)) : String forall ActualType
+      "Expected #{partial.label} to not be less than or equal to #{label} (using <=)"
+    end
+  end
+end