Implement transition:persist-props (#975)

* Implement transition:persist-props

* Add a changeset

.changeset/real-otters-mix.md

@@ -0,0 +1,5 @@
+---
+'@astrojs/compiler': minor
+---
+
+Implement the `transition:persist-props` transformation

internal/printer/printer.go

@@ -514,6 +514,12 @@ func maybeConvertTransition(n *astro.Node) {
 				Type: astro.ExpressionAttribute,
 			})
 		}
+
+		// Do a simple rename for `transition:persist-props`
+		transitionPersistPropsIndex := transform.AttrIndex(n, transform.TRANSITION_PERSIST_PROPS)
+		if transitionPersistPropsIndex != -1 {
+			n.Attr[transitionPersistPropsIndex].Key = "data-astro-transition-persist-props"
+		}
 	}
 }
 

internal/printer/printer_test.go

@@ -3490,6 +3490,14 @@ const items = ["Dog", "Cat", "Platipus"];
 				code: `${$$maybeRenderHead($$result)}<div data-astro-transition-persist="foo"${$$addAttribute($$renderTransition($$result, "peuy4xf7", "", "foo"), "data-astro-transition-scope")}></div>`,
 			},
 		},
+		{
+			name:        "transition:persist-props converted to a data attribute",
+			source:      `<my-island transition:persist transition:persist-props="false"></my-island>`,
+			transitions: true,
+			want: want{
+				code: `${$$renderComponent($$result,'my-island','my-island',{"data-astro-transition-persist-props":"false","data-astro-transition-persist":($$createTransitionScope($$result, "otghnj5u"))})}`,
+			},
+		},
 		{
 			name:   "trailing expression",
 			source: `<Component />{}`,

internal/transform/transform.go

@@ -16,6 +16,7 @@ import (
 const TRANSITION_ANIMATE = "transition:animate"
 const TRANSITION_NAME = "transition:name"
 const TRANSITION_PERSIST = "transition:persist"
+const TRANSITION_PERSIST_PROPS = "transition:persist-props"
 
 type TransformOptions struct {
 	Scope                   string