build: Automatically determine image format to flash

The default image format is bin, but targets can override it with `"OUTPUT_EXT": "hex"` in `targets.json`. This is already taken care of in the CMake configuration generated by mbed-tools, but user still need to pass `--hex-file` if they want to run `mbed-tools compile` with `--flash` to flash a hex image. This commit makes the image selection automatic based on `OUTPUT_EXT`. Note: `--hex-file` is now redundant and thus removed. It does not make sense to have it anymore without also offering `--bin-file` for completeness.

Author: LDong-Arm

news/20210602164800.feature

@@ -0,0 +1 @@
+The `--flash` option of `mbed-tools compile` now automatically selects bin or hex image. The option `--hex-file` is removed.

src/mbed_tools/build/__init__.py

@@ -11,5 +11,5 @@
 - Export of build instructions to third party command line tools and IDEs.
 """
 from mbed_tools.build.build import build_project, generate_build_system
-from mbed_tools.build.config import generate_config
+from mbed_tools.build.config import generate_config, is_image_hex
 from mbed_tools.build.flash import flash_binary

src/mbed_tools/build/config.py

@@ -41,6 +41,19 @@ def generate_config(target_name: str, toolchain: str, program: MbedProgram) -> p
  write_file(cmake_config_file_path, cmake_file_contents)
  return cmake_config_file_path
 
+def is_image_hex(target_name: str, program: MbedProgram) -> bool:
+ """Check if a target's image format is hex instead of bin.
+
+ Args:
+ target_name: Name of the target to check image format for.
+ program: The MbedProgram to extract targets data from.
+
+ Return:
+ True if the target's "OUTPUT_EXT" is "hex" in targets.json.
+ """
+ targets_data = _load_raw_targets_data(program)
+ target_build_attributes = get_target_by_name(target_name, targets_data)
+ return "OUTPUT_EXT" in target_build_attributes and target_build_attributes["OUTPUT_EXT"] == "hex"
 
 def _load_raw_targets_data(program: MbedProgram) -> Any:
  targets_data = decode_json_file(program.mbed_os.targets_json_file)

src/mbed_tools/cli/build.py

@@ -11,7 +11,7 @@
 
 import click
 
-from mbed_tools.build import build_project, generate_build_system, generate_config, flash_binary
+from mbed_tools.build import build_project, generate_build_system, generate_config, is_image_hex, flash_binary
 from mbed_tools.devices import find_connected_device, find_all_connected_devices
 from mbed_tools.project import MbedProgram
 from mbed_tools.sterm import terminal
@@ -42,9 +42,6 @@
 @click.option(
  "-f", "--flash", is_flag=True, default=False, help="Flash the binary onto a device",
 )
-@click.option(
- "--hex-file", is_flag=True, default=False, help="Use hex file, this option should be used with '-f/--flash' option",
-)
 @click.option(
  "-s", "--sterm", is_flag=True, default=False, help="Launch a serial terminal to the device.",
 )
@@ -61,7 +58,6 @@ def build(
  mbed_target: str = "",
  clean: bool = False,
  flash: bool = False,
- hex_file: bool = False,
  sterm: bool = False,
  baudrate: int = 9600,
  mbed_os_path: str = None,
@@ -81,7 +77,6 @@ def build(
  mbed_target: The name of the Mbed target to build for.
  clean: Perform a clean build.
  flash: Flash the binary onto a device.
- hex_file: Use hex file, this option should be used with '-f/--flash' option.
  sterm: Open a serial terminal to the connected target.
  baudrate: Change the serial baud rate (ignored unless --sterm is also given).
  """
@@ -114,10 +109,9 @@ def build(
 
  if flash:
  for dev in devices:
+ hex_file = is_image_hex(mbed_target.upper(), program)
  flashed_path = flash_binary(dev.mount_points[0].resolve(), program.root, build_tree, mbed_target, hex_file)
  click.echo(f"Copied {str(flashed_path.resolve())} to {len(devices)} device(s).")
- elif hex_file:
- click.echo("'--hex-file' option should be used with '-f/--flash' option")
 
  if sterm:
  dev = devices[0]

tests/cli/test_build.py

@@ -216,7 +216,7 @@ def test_build_flash_and_hex_file_options(
  ):
  mock_find_devices.return_value = [mock.MagicMock()]
  runner = CliRunner()
- runner.invoke(build, ["--flash", "--hex-file", *DEFAULT_BUILD_ARGS])
+ runner.invoke(build, ["--flash", *DEFAULT_BUILD_ARGS])
  call_args = flash_binary.call_args
  args, kwargs = call_args
  flash_binary.assert_called_once_with(args[0], args[1], args[2], args[3], True)
@@ -241,12 +241,6 @@ def test_build_flash_only_identifier_device(
  runner.invoke(build, ["--flash", "-m", "K64F[1]", "-t", "GCC_ARM"])
  self.assertEqual(flash_binary.call_count, 1)
 
- def test_build_only_hex_file_option(self, generate_config, mbed_program, build_project, generate_build_system):
- runner = CliRunner()
- result = runner.invoke(build, ["--hex-file", *DEFAULT_BUILD_ARGS])
-
- self.assertRegex(result.output, "-f/--flash")
-
  @mock.patch("mbed_tools.cli.build.terminal")
  @mock.patch("mbed_tools.cli.build.find_connected_device")
  def test_sterm_is_started_when_flag_passed(