Add ESLint rule to enforce top-level component exports in test files

also apply it to SFT and CIT

Author: sgaczol

apps/src/tests/.eslintrc.js

@@ -0,0 +1,30 @@
+const path = require('path');
+const Module = require('module');
+
+const pluginPath = require.resolve(
+  path.join(__dirname, 'eslint-plugin-local-rules'),
+);
+const originalResolve = Module._resolveFilename;
+Module._resolveFilename = function (request, ...args) {
+  if (request === 'eslint-plugin-local-rules') {
+    return pluginPath;
+  }
+  return originalResolve.call(this, request, ...args);
+};
+
+module.exports = {
+  overrides: [
+    {
+      files: [
+        'single-feature-tests/**/*.tsx',
+        'single-feature-tests/**/*.ts',
+        'component-integration-tests/**/*.tsx',
+        'component-integration-tests/**/*.ts',
+      ],
+      plugins: ['local-rules'],
+      rules: {
+        'local-rules/require-top-level-exports': 'error',
+      },
+    },
+  ],
+};

apps/src/tests/component-integration-tests/index.tsx

@@ -20,7 +20,7 @@ type ParamsList = { [k: keyof typeof COMPONENT_SCENARIOS]: undefined } & {
   Home: undefined;
 };
 
-function HomeScreen() {
+export function HomeScreen() {
   return (
     <ScrollView contentInsetAdjustmentBehavior="automatic">
       {Object.entries(COMPONENT_SCENARIOS).map(([key, scenarioGroup]) => (

apps/src/tests/component-integration-tests/orientation/orientation-stack-in-tabs.tsx

@@ -24,7 +24,7 @@ const scenarioDescription: ScenarioDescription = {
   platforms: ['ios'],
 };
 
-function ConfigScreen() {
+export function ConfigScreen() {
   const {
     routeKey: tabRouteKey,
     routeOptions: tabRouteOptions,
@@ -70,7 +70,7 @@ const STACK_ROUTE_CONFIGS: StackRouteConfig[] = [
   },
 ];
 
-function StackScreen() {
+export function StackScreen() {
   return <StackContainer routeConfigs={STACK_ROUTE_CONFIGS} />;
 }
 

apps/src/tests/component-integration-tests/orientation/orientation-tabs-in-stack.tsx

@@ -24,7 +24,7 @@ const scenarioDescription: ScenarioDescription = {
   platforms: ['ios'],
 };
 
-function ConfigScreen() {
+export function ConfigScreen() {
   const {
     routeKey: stackRouteKey,
     routeOptions: stackRouteOptions,
@@ -81,7 +81,7 @@ const TAB_ROUTE_CONFIGS: TabRouteConfig[] = [
   },
 ];
 
-function TabsScreen() {
+export function TabsScreen() {
   return <TabsContainer routeConfigs={TAB_ROUTE_CONFIGS} />;
 }
 

apps/src/tests/eslint-plugin-local-rules/index.js

@@ -0,0 +1,5 @@
+module.exports = {
+  rules: {
+    'require-top-level-exports': require('./require-top-level-exports'),
+  },
+};

apps/src/tests/eslint-plugin-local-rules/package.json

@@ -0,0 +1,6 @@
+{
+  "name": "eslint-plugin-local-rules",
+  "version": "1.0.0",
+  "private": true,
+  "main": "index.js"
+}

apps/src/tests/eslint-plugin-local-rules/require-top-level-exports.js

@@ -0,0 +1,101 @@
+/** @type {import('eslint').Rule.RuleModule} */
+module.exports = {
+  meta: {
+    type: 'suggestion',
+    docs: {
+      description:
+        'Require top-level React component declarations to be exported',
+    },
+    schema: [],
+    messages: {
+      requireExport: 'Top-level component "{{name}}" must be exported.',
+    },
+  },
+  create(context) {
+    return {
+      Program(node) {
+        const exportedNames = collectExportedNames(node);
+
+        for (const stmt of node.body) {
+          const name = getComponentName(stmt);
+          if (name === null) {
+            continue;
+          }
+
+          if (!exportedNames.has(name)) {
+            context.report({
+              node: stmt,
+              messageId: 'requireExport',
+              data: { name },
+            });
+          }
+        }
+      },
+    };
+  },
+};
+
+function isPascalCase(name) {
+  return /^[A-Z]/.test(name);
+}
+
+function getComponentName(stmt) {
+  if (
+    stmt.type === 'FunctionDeclaration' &&
+    stmt.id?.name &&
+    isPascalCase(stmt.id.name)
+  ) {
+    return stmt.id.name;
+  }
+
+  if (stmt.type === 'VariableDeclaration' && stmt.declarations.length === 1) {
+    const decl = stmt.declarations[0];
+    const name = decl.id?.name;
+    if (
+      name &&
+      isPascalCase(name) &&
+      decl.init &&
+      (decl.init.type === 'ArrowFunctionExpression' ||
+        decl.init.type === 'FunctionExpression')
+    ) {
+      return name;
+    }
+  }
+
+  return null;
+}
+
+function collectExportedNames(program) {
+  const names = new Set();
+
+  for (const stmt of program.body) {
+    if (stmt.type === 'ExportNamedDeclaration') {
+      if (stmt.declaration) {
+        for (const name of getDeclaredNames(stmt.declaration)) {
+          names.add(name);
+        }
+      }
+      for (const specifier of stmt.specifiers) {
+        names.add(specifier.local.name);
+      }
+    }
+
+    if (stmt.type === 'ExportDefaultDeclaration') {
+      const decl = stmt.declaration;
+      if (decl.type === 'Identifier') {
+        names.add(decl.name);
+      } else if (decl.id) {
+        names.add(decl.id.name);
+      }
+    }
+  }
+
+  return names;
+}
+
+function getDeclaredNames(stmt) {
+  if (stmt.type === 'VariableDeclaration') {
+    return stmt.declarations.map(d => d.id?.name).filter(Boolean);
+  }
+  return stmt.id?.name ? [stmt.id.name] : [];
+}

apps/src/tests/single-feature-tests/index.tsx

@@ -24,7 +24,7 @@ type ParamsList = { [k: keyof typeof COMPONENT_SCENARIOS]: undefined } & {
   Home: undefined;
 };
 
-function HomeScreen() {
+export function HomeScreen() {
   return (
     <ScrollView contentInsetAdjustmentBehavior="automatic"
       testID="single-feature-tests-scrollview"> 

apps/src/tests/single-feature-tests/scroll-view-marker/test-svm-configures-scroll-view.tsx

@@ -33,7 +33,7 @@ export function App() {
   );
 }
 
-function ContentScreen() {
+export function ContentScreen() {
   return (
     <View
       style={[

apps/src/tests/single-feature-tests/split/test-command-show-column.tsx

@@ -28,7 +28,7 @@ export function App() {
   );
 }
 
-function ColumnContent(props: {
+export function ColumnContent(props: {
   columnTitle: string;
   hostRef: React.RefObject<SplitHostCommands | null>;
 }) {