diff --git a/src/services/file/FileFactory.spec.ts b/src/services/file/FileFactory.spec.ts
new file mode 100644
index 00000000..73293d55
--- /dev/null
+++ b/src/services/file/FileFactory.spec.ts
@@ -0,0 +1,105 @@
+import { writeFile } from "fs/promises";
+import { resolve } from "path";
+
+import container from "../../container";
+import { DirResult, createTmpDir } from "../../tests/tmp-dir";
+import { FileFactory } from "./FileFactory";
+import { JsonFile } from "./JsonFile";
+import { TomlFile } from "./TomlFile";
+import { TypescriptFile } from "./TypescriptFile";
+import { StdFile } from "./StdFile";
+
+describe("FileFactory", () => {
+  let testDir: DirResult;
+  let fileFactory: FileFactory;
+
+  beforeEach(() => {
+    // Initialize service before each test to not be confused by cache
+    container.snapshot();
+    fileFactory = container.get(FileFactory);
+  });
+
+  afterEach(() => {
+    container.restore();
+    testDir?.removeCallback();
+  });
+
+  describe("fromFile", () => {
+    it("should create a file from a file path", async () => {
+      testDir = await createTmpDir();
+
+      const filepath = resolve(testDir.name, "test.txt");
+      await writeFile(filepath, "test");
+
+      const file = await fileFactory.fromFile(filepath);
+      expect(file).toBeInstanceOf(StdFile);
+
+      const content = await file.getContent();
+      expect(content).toBe("test");
+    });
+
+    it("should create a file from a file path with encoding", async () => {
+      testDir = await createTmpDir();
+
+      const filepath = resolve(testDir.name, "test.txt");
+      await writeFile(filepath, "test");
+
+      const file = await fileFactory.fromFile(filepath, "utf8");
+      expect(file).toBeInstanceOf(StdFile);
+
+      const content = await file.getContent();
+      expect(content).toBe("test");
+    });
+
+    it("should throw an error when the file does not exist", async () => {
+      await expect(fileFactory.fromFile("non-existing-file")).rejects.toThrow(
+        'File "non-existing-file" does not exist'
+      );
+    });
+  });
+
+  describe("fromString", () => {
+    it("should create a file from a string", async () => {
+      const file = await fileFactory.fromString("test", "test.txt");
+
+      expect(file).toBeInstanceOf(StdFile);
+      expect(await file.getContent()).toBe("test");
+    });
+
+    it("should create a file from a string with encoding", async () => {
+      const file = await fileFactory.fromString("test", "test.txt", "utf8");
+
+      expect(file).toBeInstanceOf(StdFile);
+      expect(await file.getContent()).toBe("test");
+    });
+
+    it("should create a Json file from a string", async () => {
+      const file = await fileFactory.fromString('{"test": "test"}', "test.json");
+
+      expect(file).toBeInstanceOf(JsonFile);
+      const jsonFile = file as JsonFile;
+
+      expect(await jsonFile.getContent()).toBe('{\n  "test": "test"\n}');
+      expect(await jsonFile.getData()).toEqual({ test: "test" });
+      expect(await jsonFile.getData("test")).toEqual("test");
+      expect(await jsonFile.getData("unknown")).toBeUndefined();
+    });
+
+    it("should create a Toml file from a string", async () => {
+      const file = await fileFactory.fromString("test = 'test'", "test.toml");
+
+      expect(file).toBeInstanceOf(TomlFile);
+      expect(await file.getContent()).toBe('test = "test"\n');
+      expect(await (file as TomlFile).getData()).toEqual({ test: "test" });
+      expect(await (file as TomlFile).getData("test")).toEqual("test");
+      expect(await (file as TomlFile).getData("unknown")).toBeUndefined();
+    });
+
+    it("should create a Typescript file from a string", async () => {
+      const file = await fileFactory.fromString("console.log('test')", "test.ts");
+
+      expect(file).toBeInstanceOf(TypescriptFile);
+      expect(await file.getContent()).toBe("console.log('test')");
+    });
+  });
+});
diff --git a/src/services/file/FileFactory.ts b/src/services/file/FileFactory.ts
index c53f1cc0..c868a80f 100644
--- a/src/services/file/FileFactory.ts
+++ b/src/services/file/FileFactory.ts
@@ -61,7 +61,11 @@ export class FileFactory {
     }
   }
 
-  fromString(content: string, file: string, encoding: BufferEncoding = "utf8"): StdFile {
+  fromString(
+    content: string,
+    file: string,
+    encoding: BufferEncoding = "utf8"
+  ): StdFile | JsonFile | TomlFile | TypescriptFile {
     const args = [
       this.cliService,
       this.directoryService,
diff --git a/src/services/file/TomlFile.ts b/src/services/file/TomlFile.ts
index 97e3c436..a26dc505 100644
--- a/src/services/file/TomlFile.ts
+++ b/src/services/file/TomlFile.ts
@@ -29,8 +29,9 @@ export class TomlFile extends StdFile {
     return this.setContent(stringify(newData));
   }
 
-  getData(property?: undefined): JsonMap | undefined;
-  getData(property?: string): AnyJson | undefined {
+  getData(): JsonMap | undefined;
+  getData(property: string | undefined): AnyJson | undefined;
+  getData(property: string | undefined = undefined): AnyJson | undefined {
     if (!this.data) {
       return this.data;
     }
diff --git a/src/services/template/adapters/EtaAdapter.ts b/src/services/template/adapters/EtaAdapter.ts
index 299a4588..c7f8663c 100644
--- a/src/services/template/adapters/EtaAdapter.ts
+++ b/src/services/template/adapters/EtaAdapter.ts
@@ -10,20 +10,22 @@ import { TemplateAdapter } from "./TemplateAdapter";
 import { TemplateAdapterHelper } from "./TemplateAdapterHelper";
 
 export class EtaAdapter implements TemplateAdapter {
-  private readonly eta: Eta = new Eta({
-    views: this.templateFileService.getTemplateDirectory(),
-    debug: true,
-    cache: true, // Make Eta cache templates
-    autoEscape: false, // Not automatically XML-escape interpolations
-    autoTrim: false, // automatic whitespace trimming,
-  });
+  private readonly eta: Eta;
 
   private readonly compiledTemplates: Map<string, TemplateFunction> = new Map();
 
   constructor(
     @inject(TemplateFileService) private readonly templateFileService: TemplateFileService,
     @inject(TemplateAdapterHelper) private readonly templateAdapterHelper: TemplateAdapterHelper
-  ) {}
+  ) {
+    this.eta = new Eta({
+      views: this.templateFileService.getTemplateDirectory(),
+      debug: true,
+      cache: true, // Make Eta cache templates
+      autoEscape: false, // Not automatically XML-escape interpolations
+      autoTrim: false, // automatic whitespace trimming,
+    });
+  }
 
   async renderTemplateString(template: string, context: TemplateContext): Promise<string> {
     const compiledTemplate = await this.getCompiledTemplateString(template, template);