fix: support default parameter in snippet block

packages/svelte2tsx/src/htmlxtojsx_v2/nodes/SnippetBlock.ts

@@ -93,8 +93,11 @@ export function handleSnippet(
         ];
 
         if (snippetBlock.parameters?.length) {
-            const start = snippetBlock.parameters[0].start;
-            const end = snippetBlock.parameters.at(-1).end;
+            const first = snippetBlock.parameters[0];
+            const last = snippetBlock.parameters.at(-1);
+
+            const start = first.type === 'AssignmentPattern' ? first.left.start : first.start;
+            const end = last.type === 'AssignmentPattern' ? last.right.end : last.end;
             transforms.push([start, end]);
         }
 

packages/svelte2tsx/test/helpers.ts

@@ -320,12 +320,16 @@ export function test_samples(dir: string, transform: TransformSampleFn, js: 'js'
                     try {
                         assert.strictEqual(actual, expected, TestError.WrongExpected);
                     } catch (e) {
+                        // html2jsx tests don't have the default export
+                        const expectDefaultExportPosition = expected.lastIndexOf(
+                            '\n\nexport default class'
+                        );
+                        if (expectDefaultExportPosition === -1) {
+                            throw e;
+                        }
                         // retry with the last part (the returned default export) stripped because it's always differing between old and new,
                         // and if that fails then we're going to rethrow the original error
-                        const expectedModified = expected.substring(
-                            0,
-                            expected.lastIndexOf('\n\nexport default class')
-                        );
+                        const expectedModified = expected.substring(0, expectDefaultExportPosition);
                         const actualModified = actual.substring(0, actual.lastIndexOf('\nconst '));
                         try {
                             assert.strictEqual(

packages/svelte2tsx/test/htmlx2jsx/samples/snippet.v5/expectedv2.js

@@ -10,6 +10,10 @@
 	   { const $$_value = await (foo);{ const bar = $$_value; bar;}}
 };return __sveltets_2_any(0)};
 
+ var default_parameter/*Ωignore_startΩ*/: import('svelte').Snippet<[any]>/*Ωignore_endΩ*/ = (a = '') => {async () => {
+	a;
+};return __sveltets_2_any(0)};
+
 ;__sveltets_2_ensureSnippet(foo(1));
 ;__sveltets_2_ensureSnippet(bar());
 ;__sveltets_2_ensureSnippet(await_inside());

packages/svelte2tsx/test/htmlx2jsx/samples/snippet.v5/input.svelte

@@ -10,6 +10,10 @@
 	{#await foo then bar}{bar}{/await}
 {/snippet}
 
+{#snippet default_parameter(a = '')}
+	{a}
+{/snippet}
+
 {@render foo(1)}
 {@render bar()}
 {@render await_inside()}