Add tests on docker.#Build definition

- Simple build test
- Multi step to build a go binary

Signed-off-by: Vasek - Tom C <tom.chauveau@epitech.eu>

pkg/universe.dagger.io/docker/test/build-simple.cue

@@ -0,0 +1,38 @@
+package test
+
+import (
+	"dagger.io/dagger"
+	"dagger.io/dagger/engine"
+	"universe.dagger.io/docker"
+)
+
+// This test verify that we can correctly build a simplistic image
+// using  docker.#Build
+dagger.#Plan & {
+	#alpineImage: "index.docker.io/alpine:3.15.0@sha256:21a3deaa0d32a8057914f36584b5288d2e5ecc984380bc0118285c70fa8c9300"
+
+	#testValue: "hello world"
+
+	actions: {
+		image: docker.#Build & {
+			steps: [
+				docker.#Pull & {
+					source: #alpineImage
+				},
+				docker.#Run & {
+					script: """
+							echo -n $TEST >> /test.txt
+						"""
+					env: TEST: #testValue
+				},
+			]
+		}
+
+		verify: engine.#ReadFile & {
+			input: image.output.rootfs
+			path:  "/test.txt"
+		} & {
+			contents: #testValue
+		}
+	}
+}