Add module export detection (#505)

Allow modules to include a module_exports.lua file in their root which
will cause the file save/modules/module_name.lua to be generated
pointing to the exports file.

packages/host/src/patch.ts

@@ -47,6 +47,12 @@ export class SaveModule {
 				if (entry.isFile()) {
 					let savePath = SaveModule.moduleFilePath(relativePath, this.info.name);
 					this.files.set(savePath, await fs.readFile(fsPath));
+					if (relativePath == "module_exports.lua") {
+						this.files.set(
+							`modules/${this.info.name}.lua`,
+							Buffer.from(`return require("modules/${this.info.name}/module_exports")`, "utf-8")
+						);
+					}
 
 				} else if (entry.isDirectory()) {
 					dirs.push([fsPath, relativePath]);

test/file/modules/test/module_exports.lua

@@ -0,0 +1 @@
+-- module_exports

test/host/patch.js

@@ -28,6 +28,30 @@ describe("host/patch", function() {
 				}
 			});
 		});
+
+		describe("loadFiles()", function() {
+			const testModule = new patch.SaveModule(new lib.ModuleInfo("test", "1.0.0"));
+			const referenceFiles = new Map([
+				["modules/test/test.lua", "-- test\n"],
+				["modules/test/module_exports.lua", "-- module_exports\n"],
+				["locale/en/test.cfg", "module-test=A Test\n"],
+				["locale/en/test-locale.cfg", "module-test-locale=Test Locale\n"],
+				["modules/test.lua", "return require(\"modules/test/module_exports\")"],
+			]);
+			before(async function() {
+				await testModule.loadFiles("test/file/modules/test");
+			});
+			it("Should read the contents of all files in a module", function() {
+				assert.equal(testModule.files.size, referenceFiles.size);
+				for (let [relativePath, contents] of referenceFiles) {
+					if (!testModule.files.has(relativePath)) {
+						assert.fail(`Module is missing file: ${relativePath}`);
+					} else {
+						assert.equal(testModule.files.get(relativePath).toString("utf-8"), contents);
+					}
+				}
+			});
+		});
 	});
 
 	describe("generateLoader()", function() {