diff --git a/src/utils/__tests__/fixtures/specification.jsonl b/src/utils/__tests__/fixtures/jsonl/specification.jsonl
similarity index 100%
rename from src/utils/__tests__/fixtures/specification.jsonl
rename to src/utils/__tests__/fixtures/jsonl/specification.jsonl
diff --git a/src/utils/__tests__/jsonl.test.ts b/src/utils/__tests__/jsonl.test.ts
index 448909d..5a8ad07 100644
--- a/src/utils/__tests__/jsonl.test.ts
+++ b/src/utils/__tests__/jsonl.test.ts
@@ -80,8 +80,8 @@ describe('appendJsonLine', () => {
  */
 function fixture(name: string, { temporary = false }: { temporary?: boolean } = {}) {
   const file = temporary
-    ? path.join(__dirname, 'fixtures', `${name}.temp.jsonl`)
-    : path.join(__dirname, 'fixtures', `${name}.jsonl`);
+    ? path.join(__dirname, 'fixtures/jsonl', `${name}.temp.jsonl`)
+    : path.join(__dirname, 'fixtures/jsonl', `${name}.jsonl`);
 
   if (temporary) {
     fs.writeFileSync(file, '');
diff --git a/src/utils/__tests__/stats.test.ts b/src/utils/__tests__/stats.test.ts
new file mode 100644
index 0000000..4a0587c
--- /dev/null
+++ b/src/utils/__tests__/stats.test.ts
@@ -0,0 +1,117 @@
+import { describe, expect, it } from 'bun:test';
+import fs from 'fs';
+import path from 'path';
+
+import { name, version } from '../../../package.json';
+import { AtlasValidationError } from '../errors';
+import { getStatsPath, getStatsMetdata, createStatsFile, validateStatsFile } from '../stats';
+
+describe('getStatsPath', () => {
+  it('returns default path `<project>/.expo/stats.jsonl`', () => {
+    expect(getStatsPath('<project>')).toBe('<project>/.expo/stats.jsonl');
+  });
+});
+
+describe('getStatsMetadata', () => {
+  it('returns package name and version', () => {
+    expect(getStatsMetdata()).toMatchObject({ name, version });
+  });
+});
+
+describe('createStatsFile', () => {
+  it('creates a stats file with the correct metadata', async () => {
+    const file = fixture('create-metadata', { temporary: true });
+    await createStatsFile(file);
+    await expect(fs.promises.readFile(file, 'utf8')).resolves.toBe(
+      JSON.stringify({ name, version }) + '\n'
+    );
+  });
+
+  it('overwrites invalid stats file', async () => {
+    const file = fixture('create-invalid', { temporary: true });
+    await fs.promises.writeFile(file, JSON.stringify({ name, version: '0.0.0' }) + '\n');
+    await createStatsFile(file);
+    await expect(fs.promises.readFile(file, 'utf8')).resolves.toBe(
+      JSON.stringify({ name, version }) + '\n'
+    );
+  });
+
+  it('reuses valid stats file', async () => {
+    const file = fixture('create-valid', { temporary: true });
+    await fs.promises.writeFile(file, JSON.stringify({ name, version }) + '\n');
+    await createStatsFile(file);
+    await expect(fs.promises.readFile(file, 'utf-8')).resolves.toBe(
+      JSON.stringify({ name, version }) + '\n'
+    );
+  });
+});
+
+describe('validateStatsFile', () => {
+  it('passes for valid stats file', async () => {
+    const file = fixture('validate-valid', { temporary: true });
+    await createStatsFile(file);
+    await expect(validateStatsFile(file)).resolves.pass();
+  });
+
+  it('fails for non-existing stats file', async () => {
+    await expect(validateStatsFile('./this-file-does-not-exists')).rejects.toThrow(
+      AtlasValidationError
+    );
+  });
+
+  it('fails for invalid stats file', async () => {
+    const file = fixture('validate-invalid', { temporary: true });
+    await fs.promises.writeFile(file, JSON.stringify({ name, version: '0.0.0' }) + '\n');
+    await expect(validateStatsFile(file)).rejects.toThrow(AtlasValidationError);
+  });
+
+  it('skips validation when EXPO_ATLAS_NO_STATS_VALIDATION is true-ish', async () => {
+    using _env = env('EXPO_ATLAS_NO_STATS_VALIDATION', 'true');
+    const file = fixture('validate-skip-invalid', { temporary: true });
+    await fs.promises.writeFile(file, JSON.stringify({ name, version: '0.0.0' }) + '\n');
+    await expect(validateStatsFile(file)).resolves.pass();
+  });
+});
+
+/**
+ * Get the file path to a fixture, by name.
+ * This automatically adds the required `.jsonl` or `.temp.jsonl` extension.
+ * Use `temporary: true` to keep it out of the repository, and reset the content automatically.
+ */
+function fixture(name: string, { temporary = false }: { temporary?: boolean } = {}) {
+  const file = temporary
+    ? path.join(__dirname, 'fixtures/stats', `${name}.temp.jsonl`)
+    : path.join(__dirname, 'fixtures/stats', `${name}.jsonl`);
+
+  if (temporary) {
+    fs.writeFileSync(file, '');
+  }
+
+  return file;
+}
+
+/**
+ * Change the environment variable for the duration of a test.
+ * This uses explicit resource management to revert the environment variable after the test.
+ */
+function env(key: string, value?: string): { key: string; value?: string } & Disposable {
+  const original = process.env[key];
+
+  if (value === undefined) {
+    delete process.env[key];
+  } else {
+    process.env[key] = value;
+  }
+
+  return {
+    key,
+    value,
+    [Symbol.dispose]() {
+      if (original === undefined) {
+        delete process.env[key];
+      } else {
+        process.env[key] = value;
+      }
+    },
+  };
+}
diff --git a/src/utils/env.ts b/src/utils/env.ts
index 7f5ee27..f22a8aa 100644
--- a/src/utils/env.ts
+++ b/src/utils/env.ts
@@ -1,10 +1,10 @@
 import { boolish } from 'getenv';
 
 export const env = {
-  get EXPO_DEBUG() {
-    return boolish('EXPO_DEBUG', false);
+  get EXPO_ATLAS_DEBUG() {
+    return boolish('EXPO_ATLAS_DEBUG', false);
   },
-  get EXPO_NO_STATS_VALIDATION() {
-    return boolish('EXPO_NO_STATS_VALIDATION', false);
+  get EXPO_ATLAS_NO_STATS_VALIDATION() {
+    return boolish('EXPO_ATLAS_NO_STATS_VALIDATION', false);
   },
 };
diff --git a/src/utils/middleware.ts b/src/utils/middleware.ts
index 3c7e95f..5ff0246 100644
--- a/src/utils/middleware.ts
+++ b/src/utils/middleware.ts
@@ -33,7 +33,7 @@ export function createAtlasMiddleware(source: StatsSource) {
 
   const middleware = connect();
 
-  if (env.EXPO_DEBUG) {
+  if (env.EXPO_ATLAS_DEBUG) {
     middleware.use(morgan('tiny'));
   }
 
diff --git a/src/utils/stats.ts b/src/utils/stats.ts
index 81db280..7b46773 100644
--- a/src/utils/stats.ts
+++ b/src/utils/stats.ts
@@ -1,7 +1,7 @@
 import fs from 'fs';
 import path from 'path';
 
-import { parseJsonLine } from './jsonl';
+import { appendJsonLine, parseJsonLine } from './jsonl';
 import { name, version } from '../../package.json';
 import { env } from '../utils/env';
 import { AtlasValidationError } from '../utils/errors';
@@ -24,7 +24,7 @@ export async function validateStatsFile(statsFile: string, metadata = getStatsMe
     throw new AtlasValidationError('STATS_FILE_NOT_FOUND', statsFile);
   }
 
-  if (env.EXPO_NO_STATS_VALIDATION) {
+  if (env.EXPO_ATLAS_NO_STATS_VALIDATION) {
     return;
   }
 
@@ -42,14 +42,12 @@ export async function validateStatsFile(statsFile: string, metadata = getStatsMe
 export async function createStatsFile(filePath: string) {
   if (fs.existsSync(filePath)) {
     try {
-      await validateStatsFile(filePath);
+      return await validateStatsFile(filePath);
     } catch {
-      await fs.promises.writeFile(filePath, JSON.stringify(getStatsMetdata()) + '\n');
+      await fs.promises.writeFile(filePath, '');
     }
-
-    return;
   }
 
   await fs.promises.mkdir(path.dirname(filePath), { recursive: true });
-  await fs.promises.writeFile(filePath, JSON.stringify(getStatsMetdata()) + '\n');
+  await appendJsonLine(filePath, getStatsMetdata());
 }