Make collectDependencies smarter when evaluating the require argument

Reviewed By: BYK

Differential Revision: D6592104

fbshipit-source-id: d90a93c51cb04e38cc172eb8eda932f64fce0075

packages/metro/src/ModuleGraph/worker/__tests__/__snapshots__/collectDependencies-test.js.snap

@@ -1,5 +1,7 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
-exports[`throws on tagged template literals 1`] = `"Calls to require() expect exactly 1 string literal argument, but this was found: \`require(tag\`left-pad\`)\`."`;
+exports[`Evaluating static arguments throws on tagged template literals 1`] = `"Calls to require() expect exactly 1 string literal argument, but this was found: \`require(tag\`left-pad\`)\`."`;
 
-exports[`throws on template literals with interpolations 1`] = `"Calls to require() expect exactly 1 string literal argument, but this was found: \`require(\`left\${\\"-\\"}pad\`)\`."`;
+exports[`Evaluating static arguments throws template literals with dyncamic interpolations 1`] = `"Calls to require() expect exactly 1 string literal argument, but this was found: \`require(\`left\${foo}pad\`)\`."`;
+
+exports[`Evaluating static arguments throws when requiring non-strings 1`] = `"Calls to require() expect exactly 1 string literal argument, but this was found: \`require(1)\`."`;

packages/metro/src/ModuleGraph/worker/__tests__/collectDependencies-test.js

@@ -101,17 +101,27 @@ it('collects mixed dependencies as being sync; reverse order', () => {
   );
 });
 
-it('supports template literals as arguments', () => {
+describe('Evaluating static arguments', () => {
+  it('supports template literals as arguments', () => {
     const ast = astFromCode('require(`left-pad`)');
     const {dependencies, dependencyMapName} = collectDependencies(ast);
     expect(dependencies).toEqual([{name: 'left-pad', isAsync: false}]);
     expect(codeFromAst(ast)).toEqual(
       comparableCode(`require(${dependencyMapName}[0], \`left-pad\`);`),
     );
-});
+  });
 
-it('throws on template literals with interpolations', () => {
+  it('supports template literals with static interpolations', () => {
     const ast = astFromCode('require(`left${"-"}pad`)');
+    const {dependencies, dependencyMapName} = collectDependencies(ast);
+    expect(dependencies).toEqual([{name: 'left-pad', isAsync: false}]);
+    expect(codeFromAst(ast)).toEqual(
+      comparableCode(`require(${dependencyMapName}[0], \`left\${"-"}pad\`);`),
+    );
+  });
+
+  it('throws template literals with dyncamic interpolations', () => {
+    const ast = astFromCode('let foo;require(`left${foo}pad`)');
     try {
       collectDependencies(ast);
       throw new Error('should not reach');
@@ -119,9 +129,9 @@ it('throws on template literals with interpolations', () => {
       expect(error).toBeInstanceOf(InvalidRequireCallError);
       expect(error.message).toMatchSnapshot();
     }
-});
+  });
 
-it('throws on tagged template literals', () => {
+  it('throws on tagged template literals', () => {
     const ast = astFromCode('require(tag`left-pad`)');
     try {
       collectDependencies(ast);
@@ -130,6 +140,49 @@ it('throws on tagged template literals', () => {
       expect(error).toBeInstanceOf(InvalidRequireCallError);
       expect(error.message).toMatchSnapshot();
     }
+  });
+
+  it('supports multiple static strings concatenated', () => {
+    const ast = astFromCode('require("foo_" + "bar")');
+    const {dependencies, dependencyMapName} = collectDependencies(ast);
+    expect(dependencies).toEqual([{name: 'foo_bar', isAsync: false}]);
+    expect(codeFromAst(ast)).toEqual(
+      comparableCode(`require(${dependencyMapName}[0], "foo_" + "bar");`),
+    );
+  });
+
+  it('supports concatenating strings and template literasl', () => {
+    const ast = astFromCode('require("foo_" + "bar" + `_baz`)');
+    const {dependencies, dependencyMapName} = collectDependencies(ast);
+    expect(dependencies).toEqual([{name: 'foo_bar_baz', isAsync: false}]);
+    expect(codeFromAst(ast)).toEqual(
+      comparableCode(
+        `require(${dependencyMapName}[0], "foo_" + "bar" + \`_baz\`);`,
+      ),
+    );
+  });
+
+  it('supports using static variables in require statements', () => {
+    const ast = astFromCode('const myVar="my";require("foo_" + myVar)');
+    const {dependencies, dependencyMapName} = collectDependencies(ast);
+    expect(dependencies).toEqual([{name: 'foo_my', isAsync: false}]);
+    expect(codeFromAst(ast)).toEqual(
+      comparableCode(
+        `const myVar = \"my\"; require(${dependencyMapName}[0], "foo_" + myVar);`,
+      ),
+    );
+  });
+
+  it('throws when requiring non-strings', () => {
+    const ast = astFromCode('require(1)');
+    try {
+      collectDependencies(ast);
+      throw new Error('should not reach');
+    } catch (error) {
+      expect(error).toBeInstanceOf(InvalidRequireCallError);
+      expect(error.message).toMatchSnapshot();
+    }
+  });
 });
 
 it('exposes a string as `dependencyMapName` even without collecting dependencies', () => {

packages/metro/src/ModuleGraph/worker/collectDependencies.js

@@ -58,7 +58,7 @@ function collectDependencies(ast: Ast): CollectedDependencies {
         return;
       }
       if (isRequireCall(node.callee)) {
-        const reqNode = processRequireCall(context, node, depMapIdent);
+        const reqNode = processRequireCall(context, path, node, depMapIdent);
         visited.add(reqNode);
       }
     },
@@ -76,7 +76,7 @@ function isRequireCall(callee) {
 }
 
 function processImportCall(context, path, node, depMapIdent) {
-  const [, name] = getModuleNameFromCallArgs('import', node);
+  const [, name] = getModuleNameFromCallArgs('import', node, path);
   const index = assignDependencyIndex(context, name, 'import');
   const mapLookup = createDepMapLookup(depMapIdent, index);
   const newImport = makeAsyncRequire({
@@ -86,11 +86,15 @@ function processImportCall(context, path, node, depMapIdent) {
   path.replaceWith(newImport);
 }
 
-function processRequireCall(context, node, depMapIdent) {
-  const [nameLiteral, name] = getModuleNameFromCallArgs('require', node);
+function processRequireCall(context, path, node, depMapIdent) {
+  const [nameExpression, name] = getModuleNameFromCallArgs(
+    'require',
+    node,
+    path,
+  );
   const index = assignDependencyIndex(context, name, 'require');
   const mapLookup = createDepMapLookup(depMapIdent, index);
-  node.arguments = [mapLookup, nameLiteral];
+  node.arguments = [mapLookup, nameExpression];
   return node;
 }
 
@@ -98,21 +102,20 @@ function processRequireCall(context, node, depMapIdent) {
  * Extract the module name from `require` arguments. We support template
  * literal, for example one could write `require(`foo`)`.
  */
-function getModuleNameFromCallArgs(type, node) {
-  const args = node.arguments;
-  if (args.length !== 1) {
+function getModuleNameFromCallArgs(type, node, path) {
+  if (node.arguments.length !== 1) {
     throw invalidRequireOf(type, node);
   }
-  const nameLiteral = args[0];
-  if (nameLiteral.type === 'StringLiteral') {
-    return [nameLiteral, nameLiteral.value];
-  }
-  if (nameLiteral.type === 'TemplateLiteral') {
-    if (nameLiteral.quasis.length !== 1) {
-      throw invalidRequireOf(type, node);
-    }
-    return [nameLiteral, nameLiteral.quasis[0].value.cooked];
+
+  const nameExpression = node.arguments[0];
+
+  // Try to evaluate the first argument of the require() statement.
+  // If it can be statically evaluated, resolve it.
+  const result = path.get('arguments.0').evaluate();
+  if (result.confident && typeof result.value === 'string') {
+    return [nameExpression, result.value];
   }
+
   throw invalidRequireOf(type, node);
 }