Fix handling of packages with unexpected files.

Some file browsers helpfully create extra hidden files in any
directory they view. It may have been better to just ignore anything
without a module.json, but #106
made module.json optional, so technically any directory is a valid
module now and we need a new schema revision to change that behavior.
We could alternatively add an explicit module list to prefab.json, but
that would also require a new schema revision.

For now, just ignore all files (fixes the .DS_Store case) and any
hidden directories (just in case).

api/src/main/kotlin/com/google/prefab/api/Package.kt

@@ -78,7 +78,18 @@ class Package(val path: Path) {
      * The list of modules in this package.
      */
     val modules: List<Module> =
-        moduleDir.listFiles()?.map { Module(it.toPath(), this) }
+        // Some file browsers helpfully create extra hidden files in any
+        // directory they view. It may have been better to just ignore anything
+        // without a module.json, but https://github.com/google/prefab/pull/106
+        // made module.json optional, so technically any directory is a valid
+        // module now and we need a new schema revision to change that behavior.
+        // We could alternatively add an explicit module list to prefab.json,
+        // but that would also require a new schema revision.
+        //
+        // For now, just ignore all files (fixes the .DS_Store case) and any
+        // hidden directories (just in case).
+        moduleDir.listFiles()?.filter { it.isDirectory && !it.isHidden }
+            ?.map { Module(it.toPath(), this) }
             ?: throw RuntimeException(
                 "Unable to retrieve file list for $moduleDir"
             )

cli/src/test/kotlin/com/google/prefab/cli/PackageTest.kt

@@ -68,6 +68,26 @@ class PackageTest {
         )
     }
 
+    @Test
+    fun `can load package with unexpected files`() {
+        val packagePath = Paths.get(
+            this.javaClass.getResource("packages/has_unexpected_files").toURI()
+        )
+        val pkg = Package(packagePath)
+        assertEquals(packagePath, pkg.path)
+        assertEquals("has_unexpected_files", pkg.name)
+        assertEquals(emptyList(), pkg.dependencies)
+
+        assertEquals(1, pkg.modules.size)
+
+        val bar = pkg.modules.single()
+
+        assertEquals("bar", bar.name)
+        assertEquals(packagePath.resolve("modules/bar"), bar.path)
+        assertEquals("libbar", bar.libraryNameForPlatform(android))
+        assertEquals(emptyList(), bar.linkLibsForPlatform(android))
+    }
+
     @Test
     fun `package with unsupported platforms does not load`() {
         assertFailsWith(UnsupportedPlatformException::class) {

cli/src/test/resources/com/google/prefab/cli/packages/has_unexpected_files/modules/bar/libs/android.arm64-v8a/abi.json

@@ -0,0 +1,6 @@
+{
+  "abi": "arm64-v8a",
+  "api": 21,
+  "ndk": 19,
+  "stl": "c++_shared"
+}

cli/src/test/resources/com/google/prefab/cli/packages/has_unexpected_files/modules/bar/libs/android.armeabi-v7a/abi.json

@@ -0,0 +1,6 @@
+{
+  "abi": "armeabi-v7a",
+  "api": 16,
+  "ndk": 19,
+  "stl": "c++_shared"
+}

cli/src/test/resources/com/google/prefab/cli/packages/has_unexpected_files/modules/bar/libs/android.x86/abi.json

@@ -0,0 +1,6 @@
+{
+  "abi": "x86",
+  "api": 16,
+  "ndk": 19,
+  "stl": "c++_shared"
+}

cli/src/test/resources/com/google/prefab/cli/packages/has_unexpected_files/modules/bar/libs/android.x86_64/abi.json

@@ -0,0 +1,6 @@
+{
+  "abi": "x86_64",
+  "api": 21,
+  "ndk": 19,
+  "stl": "c++_shared"
+}

cli/src/test/resources/com/google/prefab/cli/packages/has_unexpected_files/prefab.json

@@ -0,0 +1,6 @@
+{
+  "schema_version": 1,
+  "name": "has_unexpected_files",
+  "version": "1",
+  "dependencies": []
+}