tests: migrate ops test to bats

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

tests/ops/mounts/valid/cache/main.cue

@@ -0,0 +1,25 @@
+package testing
+
+test: {
+	string
+
+	#up: [
+		{
+			do: "load"
+			from: [{do: "fetch-container", ref: "alpine"}]
+		},
+		{
+			do: "exec"
+			args: ["sh", "-c", """
+					echo "NOT SURE WHAT TO TEST YET" > /out
+				"""]
+			dir: "/"
+			mount: something: "cache"
+		},
+		{
+			do:     "export"
+			source: "/out"
+			format: "string"
+		},
+	]
+}