Support expanded mounts in Compose loader

Add a test for loading expanded mount format.

Signed-off-by: Daniel Nephin <dnephin@docker.com>

compose/loader/loader_test.go

@@ -837,13 +837,13 @@ func TestFullExample(t *testing.T) {
 			},
 		},
 		User: "someone",
-		Volumes: []string{
-			"/var/lib/mysql",
-			"/opt/data:/var/lib/mysql",
-			fmt.Sprintf("%s:/code", workingDir),
-			fmt.Sprintf("%s/static:/var/www/html", workingDir),
-			fmt.Sprintf("%s/configs:/etc/configs/:ro", homeDir),
-			"datavolume:/var/lib/mysql",
+		Volumes: []types.ServiceVolumeConfig{
+			{Target: "/var/lib/mysql", Type: "volume"},
+			{Source: "/opt/data", Target: "/var/lib/mysql", Type: "bind"},
+			{Source: workingDir, Target: "/code", Type: "bind"},
+			{Source: workingDir + "/static", Target: "/var/www/html", Type: "bind"},
+			{Source: homeDir + "/configs", Target: "/etc/configs/", Type: "bind", ReadOnly: true},
+			{Source: "datavolume", Target: "/var/lib/mysql", Type: "volume"},
 		},
 		WorkingDir: "/code",
 	}
@@ -1041,3 +1041,31 @@ services:
 	assert.Equal(t, 1, len(config.Services))
 	assert.Equal(t, expected, config.Services[0].Ports)
 }
+
+func TestLoadExpandedMountFormat(t *testing.T) {
+	config, err := loadYAML(`
+version: "3.1"
+services:
+  web:
+    image: busybox
+    volumes:
+      - type: volume
+        source: foo
+        target: /target
+        read_only: true
+volumes:
+  foo: {}
+`)
+	assert.NoError(t, err)
+
+	expected := types.ServiceVolumeConfig{
+		Type:     "volume",
+		Source:   "foo",
+		Target:   "/target",
+		ReadOnly: true,
+	}
+
+	assert.Equal(t, 1, len(config.Services))
+	assert.Equal(t, 1, len(config.Services[0].Volumes))
+	assert.Equal(t, expected, config.Services[0].Volumes[0])
+}