diff --git a/gcmtest.py b/gcmtest.py
new file mode 100644
index 0000000..a3bedc4
--- /dev/null
+++ b/gcmtest.py
@@ -0,0 +1,143 @@
+#!/usr/bin/env python3
+from pathlib import Path
+import hashlib
+import os
+import shutil
+
+
+__version__ = "0.0.1"
+__author__ = "rigodron, algoflash, GGLinnk"
+__license__ = "MIT"
+__status__ = "developpement"
+
+
+unpack_path     = Path("tests/unpack")
+repack_iso_path = Path("tests/repack_iso")
+unpack2_path    = Path("tests/unpack2")
+dolphin_path    = Path("tests/dolphin_extracts")
+# if there is a way to create symlinks on GCM filesystem, it could create strange situations
+
+
+def print_paths_differences(folder1_paths:list, folder2_paths:list):
+    backup_paths = folder2_paths.copy()
+    for path in folder1_paths:
+        if path in folder2_paths:
+            folder2_paths.remove(path)
+    for path in backup_paths:
+        if path in folder1_paths:
+            folder1_paths.remove(path)
+    print("folder1 diff :")
+    for path in folder1_paths:
+        print(path)
+    print("folder2 diff :")
+    for path in folder2_paths:
+        print(path)
+
+
+# compare two files sha256
+def compare_sha256(file1_path:Path, file2_path:Path):
+    with file1_path.open("rb") as f1, file2_path.open("rb") as f2:
+        if hashlib.sha256( f1.read() ).hexdigest() != hashlib.sha256( f2.read() ).hexdigest() :
+            return False
+    return True
+
+
+# compare two GCM
+#     -> raise an exception if there is a difference
+def verify_GCM_sha256(folder1: Path, folder2: Path):
+    print(f"compare \"{folder1}\" - \"{folder2}\"")
+    len1 = len(folder1.parts)
+    len2 = len(folder2.parts)
+    # 1. Compare names of filesystems
+    folder1_paths = [Path(*path.parts[len1:]) for path in (folder1/"root").glob('**/*')]
+    folder2_paths = [Path(*path.parts[len2:]) for path in (folder2/"root").glob('**/*')]
+    if folder1_paths != folder2_paths:
+        print_paths_differences(folder1_paths, folder2_paths)
+        raise Exception(f"Folders \"{folder1}\" and \"{folder2}\" are differents (not the sames folders or files names).")
+    # 2. Compare sys files content
+    if not compare_sha256(folder1/"sys"/"apploader.img", folder2/"sys"/"apploader.img"):
+        raise Exception(f"\"{folder1}/sys/apploader.bin\" and \"{folder2}/sys/apploader.bin\" are differents.")
+    if not compare_sha256(folder1/"sys"/"boot.dol", folder2/"sys"/"boot.dol"):
+        raise Exception(f"\"{folder1}/sys/boot.bin\" and \"{folder2}/sys/boot.bin\" are differents.")
+
+    for path1 in (folder1/"root").glob('**/*'):
+        if path1.is_file():
+            path2 = folder2/Path(*path1.parts[len1:])
+            if not compare_sha256(path1, path2):
+                raise Exception(f"\"{path1}/\" and \"{path2}\" are differents.")
+
+
+print("# Cleaning tests folder")
+# Remove tests folders
+if unpack_path.is_dir():
+    shutil.rmtree(unpack_path)
+if repack_iso_path.is_dir():
+    shutil.rmtree(repack_iso_path)
+if unpack2_path.is_dir():
+    shutil.rmtree(unpack2_path)
+
+print("# Comparing unpacked ROMs with dolphin extracts")
+# unpack ROM in unpack
+unpack_path.mkdir(parents=True)
+for iso_path in Path("../ROM").glob("*"):
+    if iso_path.is_file():
+        if os.system(f"python gcmtool.py -u \"{iso_path}\" \"{unpack_path}/{iso_path.name}\"") != 0:
+            raise Exception("Error")
+
+# compare unpack dolphin_extracts
+for folder_path in unpack_path.glob("*"):
+    verify_GCM_sha256(folder_path, dolphin_path / folder_path.name)
+
+print("# Comparing iso->[1:unpacked]->repacked->[2:unpacked]")
+# repack unpack repack_iso
+repack_iso_path.mkdir()
+for folder_path in unpack_path.glob("*"):
+    if os.system(f"python gcmtool.py -p \"{folder_path}\" \"{repack_iso_path}/{folder_path.name}\"") != 0:
+        raise Exception("Error")
+
+# unpack repack_iso unpack2
+unpack2_path.mkdir()
+for iso_path in repack_iso_path.glob("*"):
+    if os.system(f"python gcmtool.py -u \"{iso_path}\" \"{unpack2_path}/{iso_path.name}\"") != 0:
+        raise Exception("Error")
+
+# remove repack_iso
+shutil.rmtree(repack_iso_path)
+
+# compare unpack unpack2
+for folder_path in unpack_path.glob("*"):
+    verify_GCM_sha256(folder_path, unpack2_path / folder_path.name)
+
+# remove unpack2
+shutil.rmtree(unpack2_path)
+
+print("# Comparing iso->[1:unpacked]->rebuild_fst->repack->[2:unpacked]")
+# rebuild unpack fst
+for folder_path in unpack_path.glob("*"):
+    if os.system(f"python gcmtool.py -r \"{folder_path}\"") != 0:
+        raise Exception("Error")
+
+# repack unpack repack_iso
+repack_iso_path.mkdir()
+for folder_path in unpack_path.glob("*"):
+    if os.system(f"python gcmtool.py -p \"{folder_path}\" \"{repack_iso_path}/{folder_path.name}\"") != 0:
+        raise Exception("Error")
+
+# unpack repack_iso unpack2
+unpack2_path.mkdir()
+for iso_path in repack_iso_path.glob("*"):
+    if os.system(f"python gcmtool.py -u \"{iso_path}\" \"{unpack2_path}/{iso_path.name}\"") != 0:
+        raise Exception("Error")
+
+# remove repack_iso
+shutil.rmtree(repack_iso_path)
+
+# compare unpack unpack2
+for folder_path in unpack_path.glob("*"):
+    verify_GCM_sha256(folder_path, unpack2_path / folder_path.name)
+
+# remove unpack unpack2
+shutil.rmtree(unpack_path)
+shutil.rmtree(unpack2_path)
+
+print("# All tests are OK")