Fix fprime-util purge error on broken directory (nasa#247)

* Fixes fprime-util purge error on broken directory

* Fixed file creation and formatting

* Refactored nested conditional

* Fixed formatting

* Remove empty directory check

* Update src/fprime/fbuild/cmake.py

Co-authored-by: Thomas Boyer-Chammard <49786685+thomas-bc@users.noreply.github.com>

* Update src/fprime/fbuild/builder.py

Co-authored-by: Thomas Boyer-Chammard <49786685+thomas-bc@users.noreply.github.com>

* Updated tests

---------

Co-authored-by: Thomas Boyer-Chammard <49786685+thomas-bc@users.noreply.github.com>

Author: tylerrussin

src/fprime/fbuild/builder.py

@@ -110,27 +110,32 @@ def load(self, platform: str = None, build_dir: Path = None, skip_validation=Fal
             InvalidBuildCacheException: the build cache does not exist as it must
         """
         self.__setup_default(platform, build_dir)
-        if not skip_validation and (
-            not self.build_dir.exists()
-            or not (self.build_dir / "CMakeCache.txt").exists()
+
+        if skip_validation:
+            return
+        if (
+            self.build_dir is not None
+            and (self.build_dir / ".fprime-build-dir").exists()
         ):
-            # Message for hard-supplied --build-cache message
-            if build_dir is not None:
-                gen_args = f" --build-cache {build_dir}"
-            else:
-                gen_args = " --ut" if self.build_type == BuildType.BUILD_TESTING else ""
-                gen_args += (
-                    " " + platform
-                    if platform is not None
-                    and platform != "native"
-                    and platform != "default"
-                    else ""
-                )
-            msg = f"'{self.build_dir}' is not a valid build cache. Generate this build cache with 'fprime-util generate{gen_args} ...'"
-            raise InvalidBuildCacheException(
-                msg,
-                self.build_dir,
+            return
+
+        # Message for hard-supplied --build-cache message
+        if build_dir is not None:
+            gen_args = f" --build-cache {build_dir}"
+        else:
+            gen_args = " --ut" if self.build_type == BuildType.BUILD_TESTING else ""
+            gen_args += (
+                " " + platform
+                if platform is not None
+                and platform != "native"
+                and platform != "default"
+                else ""
             )
+        msg = f"'{self.build_dir}' is not a valid build cache. Generate this build cache with 'fprime-util generate{gen_args} ...'"
+        raise InvalidBuildCacheException(
+            msg,
+            self.build_dir,
+        )
 
     def get_settings(
         self,

src/fprime/fbuild/cmake.py

@@ -14,6 +14,7 @@
 import functools
 import itertools
 import os
+from pathlib import Path
 import pty
 import re
 import selectors
@@ -280,6 +281,8 @@ def generate_build(
             ),
             args.keys(),
         )
+        # Creating a file to mark the directory as a F Prime directory
+        (Path(build_dir) / ".fprime-build-dir").touch()
         self.cmake_validate_source_dir(source_dir)
         self._run_cmake(
             ["-S", source_dir] + list(fleshed_args),

test/fprime/fbuild/test_build.py

@@ -46,7 +46,9 @@ def test_hash_finder():
     builder = fprime.fbuild.builder.Build(
         fprime.fbuild.builder.BuildType.BUILD_NORMAL, dep_dir
     )
-    builder.load(local, build_dir=dep_dir / "build-fprime-automatic-native")
+    builder.load(
+        local, build_dir=dep_dir / "build-fprime-automatic-native", skip_validation=True
+    )
 
     assert builder.find_hashed_file(0xDEADBEEF) == ["Abc: 0xdeadbeef\n"]
     assert builder.find_hashed_file(0xC0DEC0DE) == ["HJK: 0xc0dec0de\n"]

test/fprime/fbuild/test_cmake.py

@@ -1,8 +1,9 @@
-""" Test CMake interaction
+"""Test CMake interaction
 
 This file contains a set of tests for validating CMake interaction on the back-end of fprime-util. These tests poke at
 the CMakeHandler component.
 """
+
 import json
 import os
 import shutil
@@ -460,6 +461,7 @@ def test_refresh_cache_noop_with_environment(cmake_handler):
 
 @patch("os.makedirs")
 @patch("os.path.exists")
+@patch("pathlib.Path.touch")
 @patch("fprime.fbuild.cmake.CMakeHandler.cmake_validate_source_dir")
 @patch("fprime.fbuild.cmake.CMakeHandler._run_cmake")
 def generate_build(
@@ -468,6 +470,7 @@ def generate_build(
     cmake_handler,
     mock_run_cmake,
     mock_validate_source_dir,
+    mock_touch,
     mock_path_exists,
     mock_makedirs,
     **kwargs,
@@ -493,6 +496,9 @@ def generate_build(
     # Call the generate_build function
     cmake_handler.generate_build(source_dir, build_dir, **kwargs)
 
+    # Asset that the touch method was called once
+    mock_touch.assert_called_once()
+
     # Assert that cmake_validate_source_dir was called with the correct source_dir
     mock_validate_source_dir.assert_called_once_with(source_dir)