socket: add tests

Signed-off-by: Andrea Luzzardi <aluzzardi@gmail.com>

tests/core/socket/main.cue

@@ -0,0 +1,23 @@
+package main
+
+import (
+	"alpha.dagger.io/dagger"
+	"alpha.dagger.io/dagger/op"
+	"alpha.dagger.io/alpine"
+)
+
+dockersocket: dagger.#Socket & dagger.#Input
+
+TestDockerSocket: #up: [
+	op.#Load & {
+		from: alpine.#Image & {
+			package: "docker-cli": true
+		}
+	},
+
+	op.#Exec & {
+		always: true
+		mount: "/var/run/docker.sock": socket: dockersocket
+		args: ["docker", "info"]
+	},
+]