POC

vendor/github.com/onsi/gomega/matchers/have_cap_matcher.go

@@ -0,0 +1,30 @@
+// untested sections: 2
+
+package matchers
+
+import (
+	"fmt"
+
+	"github.com/onsi/gomega/format"
+)
+
+type HaveCapMatcher struct {
+	Count int
+}
+
+func (matcher *HaveCapMatcher) Match(actual interface{}) (success bool, err error) {
+	length, ok := capOf(actual)
+	if !ok {
+		return false, fmt.Errorf("HaveCap matcher expects a array/channel/slice.  Got:\n%s", format.Object(actual, 1))
+	}
+
+	return length == matcher.Count, nil
+}
+
+func (matcher *HaveCapMatcher) FailureMessage(actual interface{}) (message string) {
+	return fmt.Sprintf("Expected\n%s\nto have capacity %d", format.Object(actual, 1), matcher.Count)
+}
+
+func (matcher *HaveCapMatcher) NegatedFailureMessage(actual interface{}) (message string) {
+	return fmt.Sprintf("Expected\n%s\nnot to have capacity %d", format.Object(actual, 1), matcher.Count)
+}