Fix compile --build-path not working with relative paths (#1423)

commands/compile/compile.go

@@ -144,7 +144,7 @@ func Compile(ctx context.Context, req *rpc.CompileRequest, outStream, errStream
 	if req.GetBuildPath() == "" {
 		builderCtx.BuildPath = sk.BuildPath
 	} else {
-		builderCtx.BuildPath = paths.New(req.GetBuildPath())
+		builderCtx.BuildPath = paths.New(req.GetBuildPath()).Canonical()
 	}
 	if err = builderCtx.BuildPath.MkdirAll(); err != nil {
 		return nil, &commands.PermissionDeniedError{Message: tr("Cannot create build directory"), Cause: err}

test/test_compile.py

@@ -1155,3 +1155,33 @@ def test_compile_sketch_with_ipp_file_include(run_command, copy_sketch):
     fqbn = "arduino:avr:uno"
 
     assert run_command(f"compile -b {fqbn} {sketch_path} --verbose")
+
+
+def test_compile_with_relative_build_path(run_command, data_dir, copy_sketch):
+    assert run_command("update")
+
+    run_command("core install arduino:avr@1.8.3")
+
+    sketch_name = "sketch_simple"
+    sketch_path = copy_sketch(sketch_name)
+    fqbn = "arduino:avr:uno"
+
+    build_path = Path("..", "build_path")
+    working_dir = Path(data_dir, "working_dir")
+    working_dir.mkdir()
+    assert run_command(f"compile -b {fqbn} --build-path {build_path} {sketch_path} -v", custom_working_dir=working_dir)
+
+    absolute_build_path = Path(data_dir, "build_path")
+    built_files = [f.name for f in absolute_build_path.glob("*")]
+    assert f"{sketch_name}.ino.eep" in built_files
+    assert f"{sketch_name}.ino.elf" in built_files
+    assert f"{sketch_name}.ino.hex" in built_files
+    assert f"{sketch_name}.ino.with_bootloader.bin" in built_files
+    assert f"{sketch_name}.ino.with_bootloader.hex" in built_files
+    assert "build.options.json" in built_files
+    assert "compile_commands.json" in built_files
+    assert "core" in built_files
+    assert "includes.cache" in built_files
+    assert "libraries" in built_files
+    assert "preproc" in built_files
+    assert "sketch" in built_files