fix: reuseExistingChunk should be false by default

crates/rspack_binding_options/src/options/raw_split_chunks/mod.rs

@@ -211,7 +211,7 @@ impl From<RawSplitChunksOptions> for rspack_plugin_split_chunks::PluginOptions {
               .automatic_name_delimiter
               .unwrap_or(overall_automatic_name_delimiter.clone()),
             filename: v.filename.map(Filename::from),
-            reuse_existing_chunk: v.reuse_existing_chunk.unwrap_or(true),
+            reuse_existing_chunk: v.reuse_existing_chunk.unwrap_or(false),
             // TODO(hyf0): the non-enforced default value should be 30
             // I would set align default value with Webpack when the options is exposed to users
             max_async_requests: u32::MAX,

packages/rspack-test-tools/tests/configCases/split-chunks/default-reuse-existing-chunk/foo.js

@@ -0,0 +1 @@
+export const foo = 42;

packages/rspack-test-tools/tests/configCases/split-chunks/default-reuse-existing-chunk/index.js

@@ -0,0 +1,6 @@
+import fs from 'fs'
+import path from 'path'
+
+it('should have extra chunk', () => {
+	expect(fs.existsSync(path.resolve(__dirname, 'foo-index_js.js'))).toBe(true)
+})

packages/rspack-test-tools/tests/configCases/split-chunks/default-reuse-existing-chunk/rspack.config.js

@@ -0,0 +1,19 @@
+/** @type {import("@rspack/core").Configuration} */
+module.exports = {
+	target: "node",
+	output: {
+		filename: "[name].js"
+	},
+	optimization: {
+		chunkIds: 'named',
+		splitChunks: {
+			minSize: 1,
+      chunks: "all",
+			cacheGroups: {
+				foo: {
+					minSize: 0,
+				}
+			}
+		}
+	}
+};

packages/rspack-test-tools/tests/configCases/split-chunks/default-reuse-existing-chunk/test.config.js

@@ -0,0 +1,6 @@
+/** @type {import("../../../..").TConfigCaseConfig} */
+module.exports = {
+	findBundle: function (i, options) {
+		return ["main.js"];
+	}
+};