From ba713f173da6dd48b9ef95e6be68053c9e3405ad Mon Sep 17 00:00:00 2001
From: Ben McCann <322311+benmccann@users.noreply.github.com>
Date: Wed, 16 Nov 2022 10:46:00 -0800
Subject: [PATCH] [feat] warn if svelte not found in dependencies or
 peerDependencies

---
 .changeset/gentle-rocks-run.md |  5 +++++
 packages/package/src/index.js  | 12 ++++++++++++
 2 files changed, 17 insertions(+)
 create mode 100644 .changeset/gentle-rocks-run.md

diff --git a/.changeset/gentle-rocks-run.md b/.changeset/gentle-rocks-run.md
new file mode 100644
index 000000000000..5730b5b8f60d
--- /dev/null
+++ b/.changeset/gentle-rocks-run.md
@@ -0,0 +1,5 @@
+---
+'@sveltejs/package': patch
+---
+
+[feat] warn if svelte not found in dependencies or peerDependencies
diff --git a/packages/package/src/index.js b/packages/package/src/index.js
index d751537bf1cf..08a096a4ac04 100644
--- a/packages/package/src/index.js
+++ b/packages/package/src/index.js
@@ -32,6 +32,10 @@ export async function build(config, cwd = process.cwd()) {
 
 	const pkg = generate_pkg(cwd, files);
 
+	if (!has_svelte(pkg.dependencies) && !has_svelte(pkg.peerDependencies)) {
+		console.warn('Svelte libraries should include "svelte" in either "dependencies" or "peerDependencies".');
+	}
+
 	if (!pkg.svelte && files.some((file) => file.is_svelte)) {
 		// Several heuristics in Kit/vite-plugin-svelte to tell Vite to mark Svelte packages
 		// rely on the "svelte" property. Vite/Rollup/Webpack plugin can all deal with it.
@@ -82,6 +86,14 @@ export async function build(config, cwd = process.cwd()) {
 	console.log(colors.bold().cyan('  npm publish\n'));
 }
 
+/** @param {object} field */
+function has_svelte(field) {
+	for (const key of Object.keys(field)) {
+		if (key === 'svelte') return true;
+	}
+	return false;
+}
+
 /**
  * @param {import('./types').ValidatedConfig} config
  */