Add export and load for dagger images

Signed-off-by: Helder Correia <174525+helderco@users.noreply.github.com>

pkg/universe.dagger.io/docker/test/load.cue

@@ -0,0 +1,57 @@
+package docker
+
+import (
+	"dagger.io/dagger"
+
+	"universe.dagger.io/alpine"
+	"universe.dagger.io/bash"
+	"universe.dagger.io/docker"
+)
+
+dagger.#Plan & {
+	client: filesystem: "/var/run/docker.sock": read: contents: dagger.#Service
+
+	actions: test: load: {
+		_cli: alpine.#Build & {
+			packages: {
+				bash: {}
+				"docker-cli": {}
+			}
+		}
+
+		_image: docker.#Run & {
+			input: _cli.output
+			command: {
+				name: "touch"
+				args: ["/foo.bar"]
+			}
+		}
+
+		load: docker.#Load & {
+			image: _image.output
+			host:  client.filesystem."/var/run/docker.sock".read.contents
+			tag:   "dagger:load"
+		}
+
+		verify: bash.#Run & {
+			input: _cli.output
+			mounts: docker: {
+				contents: client.filesystem."/var/run/docker.sock".read.contents
+				dest:     "/var/run/docker.sock"
+			}
+			env: {
+				IMAGE_NAME: load.tag
+				IMAGE_ID:   load.imageID
+				// FIXME: without this forced dependency, load.command might not run
+				DEP: "\(load.success)"
+			}
+			script: contents: #"""
+				test "$(docker image inspect $IMAGE_NAME -f '{{.Id}}')" = "$IMAGE_ID"
+				docker run --rm $IMAGE_NAME stat /foo.bar
+				"""#
+		}
+	}
+
+	// FIXME: test remote connections with `docker:dind`
+	// image when we have long running tasks
+}