websvc: add test; imp names, docs

internal/aghchan/aghchan.go

@@ -0,0 +1,19 @@
+// Package aghchan contains channel utilities.
+package aghchan
+
+import (
+	"fmt"
+	"time"
+)
+
+// MustReceive panics if it cannot receive a value form c before timeout runs
+// out.
+func MustReceive[T any](c <-chan T, timeout time.Duration) (v T, ok bool) {
+	timeoutCh := time.After(timeout)
+	select {
+	case <-timeoutCh:
+		panic(fmt.Errorf("did not receive after %s", timeout))
+	case v, ok = <-c:
+		return v, ok
+	}
+}