Add test fixtures demonstrating export statement validation bugs (#75277)

The issues with the current export statement validation for app router
pages are documented in the added fixtures, see also the inline comments
in the diff.

Author: unstubbable

crates/next-custom-transforms/tests/errors.rs

@@ -89,45 +89,20 @@ fn next_ssg_errors(input: PathBuf) {
     );
 }
 
-#[fixture("tests/errors/react-server-components/server-graph/**/input.js")]
-fn react_server_components_server_graph_errors(input: PathBuf) {
-    use next_custom_transforms::transforms::react_server_components::{Config, Options};
-    let output = input.parent().unwrap().join("output.js");
-    test_fixture(
-        syntax(),
-        &|tr| {
-            server_components(
-                FileName::Real(PathBuf::from("/some-project/src/layout.js")).into(),
-                Config::WithOptions(Options {
-                    is_react_server_layer: true,
-                    dynamic_io_enabled: false,
-                }),
-                tr.comments.as_ref().clone(),
-                None,
-            )
-        },
-        &input,
-        &output,
-        FixtureTestConfig {
-            allow_error: true,
-            module: Some(true),
-            ..Default::default()
-        },
-    );
-}
-
-#[fixture("tests/errors/react-server-components/client-graph/**/input.js")]
-fn react_server_components_client_graph_errors(input: PathBuf) {
+#[fixture("tests/errors/react-server-components/**/input.js")]
+fn react_server_components_errors(input: PathBuf) {
     use next_custom_transforms::transforms::react_server_components::{Config, Options};
+    let is_react_server_layer = input.iter().any(|s| s.to_str() == Some("server-graph"));
+    let dynamic_io_enabled = input.iter().any(|s| s.to_str() == Some("dynamic-io"));
     let output = input.parent().unwrap().join("output.js");
     test_fixture(
         syntax(),
         &|tr| {
             server_components(
                 FileName::Real(PathBuf::from("/some-project/src/page.js")).into(),
                 Config::WithOptions(Options {
-                    is_react_server_layer: false,
-                    dynamic_io_enabled: false,
+                    is_react_server_layer,
+                    dynamic_io_enabled,
                 }),
                 tr.comments.as_ref().clone(),
                 None,
@@ -164,50 +139,10 @@ fn next_font_loaders_errors(input: PathBuf) {
     );
 }
 
-#[fixture("tests/errors/server-actions/server-graph/**/input.js")]
-fn react_server_actions_server_errors(input: PathBuf) {
-    use next_custom_transforms::transforms::react_server_components::{Config, Options};
-    let output = input.parent().unwrap().join("output.js");
-    test_fixture(
-        syntax(),
-        &|tr| {
-            (
-                resolver(Mark::new(), Mark::new(), false),
-                server_components(
-                    FileName::Real(PathBuf::from("/app/item.js")).into(),
-                    Config::WithOptions(Options {
-                        is_react_server_layer: true,
-                        dynamic_io_enabled: true,
-                    }),
-                    tr.comments.as_ref().clone(),
-                    None,
-                ),
-                server_actions(
-                    &FileName::Real("/app/item.js".into()),
-                    server_actions::Config {
-                        is_react_server_layer: true,
-                        use_cache_enabled: true,
-                        hash_salt: "".into(),
-                        cache_kinds: FxHashSet::default(),
-                    },
-                    tr.comments.as_ref().clone(),
-                    Default::default(),
-                ),
-            )
-        },
-        &input,
-        &output,
-        FixtureTestConfig {
-            allow_error: true,
-            module: Some(true),
-            ..Default::default()
-        },
-    );
-}
-
-#[fixture("tests/errors/server-actions/client-graph/**/input.js")]
-fn react_server_actions_client_errors(input: PathBuf) {
+#[fixture("tests/errors/server-actions/**/input.js")]
+fn react_server_actions_errors(input: PathBuf) {
     use next_custom_transforms::transforms::react_server_components::{Config, Options};
+    let is_react_server_layer = input.iter().any(|s| s.to_str() == Some("server-graph"));
     let output = input.parent().unwrap().join("output.js");
     test_fixture(
         syntax(),
@@ -217,7 +152,7 @@ fn react_server_actions_client_errors(input: PathBuf) {
                 server_components(
                     FileName::Real(PathBuf::from("/app/item.js")).into(),
                     Config::WithOptions(Options {
-                        is_react_server_layer: false,
+                        is_react_server_layer,
                         dynamic_io_enabled: true,
                     }),
                     tr.comments.as_ref().clone(),
@@ -226,7 +161,7 @@ fn react_server_actions_client_errors(input: PathBuf) {
                 server_actions(
                     &FileName::Real("/app/item.js".into()),
                     server_actions::Config {
-                        is_react_server_layer: false,
+                        is_react_server_layer,
                         use_cache_enabled: true,
                         hash_salt: "".into(),
                         cache_kinds: FxHashSet::default(),

crates/next-custom-transforms/tests/errors/react-server-components/client-graph/generate-metadata/input.js

@@ -0,0 +1,5 @@
+export function generateMetadata() {}
+
+export default function () {
+  return null
+}

crates/next-custom-transforms/tests/errors/react-server-components/client-graph/generate-metadata/output.js

@@ -0,0 +1,4 @@
+export function generateMetadata() {}
+export default function() {
+    return null;
+}

crates/next-custom-transforms/tests/errors/react-server-components/client-graph/generate-metadata/output.stderr

@@ -0,0 +1,8 @@
+  x You are attempting to export "generateMetadata" from a component marked with "use client", which is disallowed. Either remove the export, or the "use client" directive. Read more: https://
+  | nextjs.org/docs/app/api-reference/directives/use-client
+  | 
+  | 
+   ,-[input.js:1:1]
+ 1 | export function generateMetadata() {}
+   :                 ^^^^^^^^^^^^^^^^
+   `----

crates/next-custom-transforms/tests/errors/react-server-components/client-graph/metadata/input.js

@@ -0,0 +1,5 @@
+export const metadata = {}
+
+export default function () {
+  return null
+}

crates/next-custom-transforms/tests/errors/react-server-components/client-graph/metadata/output.js

@@ -0,0 +1,4 @@
+export const metadata = {};
+export default function() {
+    return null;
+}

crates/next-custom-transforms/tests/errors/react-server-components/client-graph/metadata/output.stderr

@@ -0,0 +1,8 @@
+  x You are attempting to export "metadata" from a component marked with "use client", which is disallowed. Either remove the export, or the "use client" directive. Read more: https://nextjs.org/
+  | docs/app/api-reference/directives/use-client
+  | 
+  | 
+   ,-[input.js:1:1]
+ 1 | export const metadata = {}
+   :              ^^^^^^^^
+   `----

crates/next-custom-transforms/tests/errors/react-server-components/client-graph/multiple/input.js

@@ -0,0 +1,9 @@
+export const metadata = {}
+
+export function generateMetadata() {}
+
+export function getServerSideProps() {}
+
+export default function () {
+  return null
+}

crates/next-custom-transforms/tests/errors/react-server-components/client-graph/multiple/output.js

@@ -0,0 +1,6 @@
+export const metadata = {};
+export function generateMetadata() {}
+export function getServerSideProps() {}
+export default function() {
+    return null;
+}

crates/next-custom-transforms/tests/errors/react-server-components/client-graph/multiple/output.stderr

@@ -0,0 +1,17 @@
+  x You are attempting to export "getServerSideProps" from a component marked with "use client", which is disallowed. Either remove the export, or the "use client" directive. Read more: https://
+  | nextjs.org/docs/app/api-reference/directives/use-client
+  | 
+  | 
+   ,-[input.js:5:1]
+ 4 | 
+ 5 | export function getServerSideProps() {}
+   :                 ^^^^^^^^^^^^^^^^^^
+   `----
+  x "getServerSideProps" is not supported in app/. Read more: https://nextjs.org/docs/app/building-your-application/data-fetching
+  | 
+  | 
+   ,-[input.js:5:1]
+ 4 | 
+ 5 | export function getServerSideProps() {}
+   :                 ^^^^^^^^^^^^^^^^^^
+   `----