config: Simplify write_file interface

Author: rwalton-arm

src/mbed_tools/build/_internal/write_files.py

@@ -7,8 +7,8 @@
 from mbed_tools.build.exceptions import InvalidExportOutputDirectory
 
 
-def write_file(output_directory: pathlib.Path, file_name: str, file_contents: str) -> None:
-    """Writes out a file to a directory.
+def write_file(file_path: pathlib.Path, file_contents: str) -> None:
+    """Writes out a string to a file.
 
     If the intermediate directories to the output directory don't exist,
     this function will create them.
@@ -19,9 +19,9 @@ def write_file(output_directory: pathlib.Path, file_name: str, file_contents: st
     Raises:
         InvalidExportOutputDirectory: it's not possible to export to the output directory provided
     """
+    output_directory = file_path.parent
     if output_directory.is_file():
         raise InvalidExportOutputDirectory("Output directory cannot be a path to a file.")
 
     output_directory.mkdir(parents=True, exist_ok=True)
-    output_file = output_directory.joinpath(file_name)
-    output_file.write_text(file_contents)
+    file_path.write_text(file_contents)

src/mbed_tools/build/config.py

@@ -33,5 +33,5 @@ def generate_config(target_name: str, toolchain: str, program: MbedProgram) -> p
         toolchain_name=toolchain,
     )
     cmake_config_file_path = program.files.cmake_config_file
-    write_file(cmake_config_file_path.parent, cmake_config_file_path.name, cmake_file_contents)
+    write_file(cmake_config_file_path, cmake_file_contents)
     return cmake_config_file_path

tests/build/_internal/test_write_files.py

@@ -14,17 +14,16 @@ class TestWriteFile(TestCase):
     def test_writes_content_to_file(self):
         with tempfile.TemporaryDirectory() as directory:
             content = "Some rendered content"
-            export_path = pathlib.Path(directory, "output")
-            file_name = "some_file.txt"
+            export_path = pathlib.Path(directory, "output", "some_file.txt")
 
-            write_file(export_path, file_name, content)
+            write_file(export_path, content)
 
-            created_file = pathlib.Path(export_path, pathlib.Path(export_path, file_name))
+            created_file = pathlib.Path(export_path)
             self.assertEqual(created_file.read_text(), content)
 
     def test_output_dir_is_file(self):
         with tempfile.TemporaryDirectory() as directory:
-            bad_export_dir = pathlib.Path(directory, "some_file.txt")
-            bad_export_dir.touch()
+            bad_export_dir = pathlib.Path(directory, "some_file.txt", ".txt")
+            bad_export_dir.parent.touch()
             with self.assertRaises(InvalidExportOutputDirectory):
-                write_file(bad_export_dir, "any_file.txt", "some contents")
+                write_file(bad_export_dir, "some contents")