fix(migrate): do not downgrade versions (#10352)

* fix(migrate): do not downgrade versions

* changeset

.changeset/cold-boxes-build.md

@@ -0,0 +1,5 @@
+---
+'svelte-migrate': patch
+---
+
+fix: do not downgrade versions

packages/migrate/migrations/svelte-4/migrate.js

@@ -1,5 +1,6 @@
 import fs from 'node:fs';
 import { Project, ts, Node } from 'ts-morph';
+import semver from 'semver';
 
 export function update_pkg_json() {
 	fs.writeFileSync(
@@ -22,12 +23,21 @@ export function update_pkg_json_content(content) {
 	 */
 	function update_pkg(name, version, additional = '') {
 		if (pkg.dependencies?.[name]) {
-			log_migration(`Updated ${name} to ${version} ${additional}`);
-			pkg.dependencies[name] = version;
+			const existing_range = pkg.dependencies[name];
+
+			if (semver.validRange(existing_range) && !semver.subset(existing_range, version)) {
+				log_migration(`Updated ${name} to ${version} ${additional}`);
+				pkg.dependencies[name] = version;
+			}
 		}
+
 		if (pkg.devDependencies?.[name]) {
-			log_migration(`Updated ${name} to ${version} ${additional}`);
-			pkg.devDependencies[name] = version;
+			const existing_range = pkg.devDependencies[name];
+
+			if (semver.validRange(existing_range) && !semver.subset(existing_range, version)) {
+				log_migration(`Updated ${name} to ${version} ${additional}`);
+				pkg.devDependencies[name] = version;
+			}
 		}
 	}
 

packages/migrate/migrations/svelte-4/migrate.spec.js

@@ -362,3 +362,22 @@ test('Update package.json', () => {
 }`
 	);
 });
+
+
+test('Does not downgrade versions', () => {
+	const result = update_pkg_json_content(`{
+	"devDependencies": {
+		"svelte": "^4.0.5",
+		"typescript": "github:idk"
+	}
+}`);
+	assert.equal(
+		result,
+		`{
+	"devDependencies": {
+		"svelte": "^4.0.5",
+		"typescript": "github:idk"
+	}
+}`
+	);
+});

packages/migrate/package.json

@@ -27,13 +27,15 @@
 		"kleur": "^4.1.5",
 		"magic-string": "^0.30.0",
 		"prompts": "^2.4.2",
+		"semver": "^7.5.3",
 		"tiny-glob": "^0.2.9",
 		"ts-morph": "^19.0.0",
 		"typescript": "^5.0.4"
 	},
 	"devDependencies": {
 		"@types/node": "^16.18.6",
 		"@types/prompts": "^2.4.1",
+		"@types/semver": "^7.5.0",
 		"prettier": "^2.8.0",
 		"vitest": "^0.32.2"
 	},