[android] Refine and test the findLibraryName function

packages/platform-android/src/config/__fixtures__/android.ts

@@ -15,9 +15,13 @@ const manifest = fs.readFileSync(
 const mainJavaClass = fs.readFileSync(
   path.join(__dirname, './files/Main.java'),
 );
+const buildGradle = fs.readFileSync(
+  path.join(__dirname, './files/build.gradle'),
+);
 
 function generateValidFileStructure(classFileName: string) {
   return {
+    'build.gradle': buildGradle,
     src: {
       'AndroidManifest.xml': manifest,
       main: {

packages/platform-android/src/config/__fixtures__/files/build.gradle

@@ -0,0 +1,6 @@
+apply package: "com.android.application"
+apply package: "com.facebook.react"
+
+react {
+    libraryName = "justalibrary"
+}

packages/platform-android/src/config/__tests__/findLibraryName.test.ts

@@ -0,0 +1,91 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ */
+
+import {findLibraryName} from '../findLibraryName';
+import * as mocks from '../__fixtures__/android';
+
+jest.mock('path');
+jest.mock('fs');
+
+const fs = require('fs');
+
+const buildGradleWithSingleQuotes = `
+  apply plugin: "com.android.application"
+  apply plugin: "com.facebook.react"
+
+  react {
+    libraryName = 'justalibrary'
+  }
+  `;
+
+const buildGradleKts = `
+  apply(id = "com.android.application")
+  apply(id = "com.facebook.react")
+
+  react {
+    libraryName.set("justalibrary")
+  }
+  `;
+
+const packageJsonWithCodegenConfig = `
+  {
+    "name": "my-awesome-library",
+    "version": "0.0.1",
+    "codegenConfig": {
+      "name": "my-awesome-library"
+    }
+  }
+  `;
+
+describe('android::findLibraryName', () => {
+  beforeAll(() => {
+    fs.__setMockFilesystem({
+      empty: {},
+      valid: {
+        android: mocks.valid,
+        singlequotes: {
+          'build.gradle': buildGradleWithSingleQuotes,
+        },
+        gradlekts: {
+          'build.gradle.kts': buildGradleKts,
+        },
+        withcodegenconfig: {
+          'package.json': packageJsonWithCodegenConfig,
+          android: {
+            'build.gradle': buildGradleWithSingleQuotes,
+          },
+        },
+      },
+    });
+  });
+
+  it('returns the library name if declared in the build.gradle file', () => {
+    expect(findLibraryName('/', '/valid/android')).toBe('justalibrary');
+  });
+
+  it('returns the library name if declared with single quotes in the build.gradle file', () => {
+    expect(findLibraryName('/', '/valid/singlequotes')).toBe('justalibrary');
+  });
+
+  it('returns the library name if declared with inside a build.gradle.kts file', () => {
+    expect(findLibraryName('/', '/valid/singlequotes')).toBe('justalibrary');
+  });
+
+  it('returns the library name if defined inside codegenConfig', () => {
+    expect(
+      findLibraryName(
+        '/valid/withcodegenconfig',
+        '/valid/withcodegenconfig/android',
+      ),
+    ).toBe('my-awesome-library');
+  });
+
+  it('returns null if there is no build.gradle file', () => {
+    expect(findLibraryName('/', '/empty')).toBeUndefined();
+  });
+});

packages/platform-android/src/config/findLibraryName.ts

@@ -1,14 +1,34 @@
 import fs from 'fs';
 import path from 'path';
 
-export function findLibraryName(sourceDir: string) {
+export function findLibraryName(root: string, sourceDir: string) {
+  const packageJsonPath = path.join(root, 'package.json');
   const buildGradlePath = path.join(sourceDir, 'build.gradle');
-  if (fs.existsSync(buildGradlePath)) {
-    const buildGradleContents = fs.readFileSync(buildGradlePath, 'utf-8');
-    const match = buildGradleContents.match(/libraryName = "(.+)"/);
-    if (match) {
-      return match[1];
+  const buildGradleKtsPath = path.join(sourceDir, 'build.gradle.kts');
+
+  // We first check if there is a codegenConfig.name inside the package.json file.
+  if (fs.existsSync(packageJsonPath)) {
+    const packageJson = JSON.parse(fs.readFileSync(packageJsonPath, 'utf8'));
+    if (packageJson.codegenConfig.name) {
+      return packageJson.codegenConfig.name;
     }
   }
-  return undefined;
+
+  // If not, we check if the library specified it in the build.gradle file.
+  let buildGradleContents = '';
+  if (fs.existsSync(buildGradlePath)) {
+    buildGradleContents = fs.readFileSync(buildGradlePath, 'utf-8');
+  } else if (fs.existsSync(buildGradleKtsPath)) {
+    buildGradleContents = fs.readFileSync(buildGradleKtsPath, 'utf-8');
+  } else {
+    return undefined;
+  }
+
+  const match = buildGradleContents.match(/libraryName = ["'](.+)["']/);
+
+  if (match) {
+    return match[1];
+  } else {
+    return undefined;
+  }
 }

packages/platform-android/src/config/index.ts

@@ -120,7 +120,8 @@ export function dependencyConfig(
 
   const buildTypes = userConfig.buildTypes || [];
   const dependencyConfiguration = userConfig.dependencyConfiguration;
-  const libraryName = userConfig.libraryName || findLibraryName(sourceDir);
+  const libraryName =
+    userConfig.libraryName || findLibraryName(root, sourceDir);
   const componentDescriptors =
     userConfig.componentDescriptors || findComponentDescriptors(root);
   const androidMkPath = userConfig.androidMkPath