Introduce KAS_BUILD_DIR environment variable

This variable can override default build path `${KAS_WORK_DIR}/build`.

Signed-off-by: Peter Hatina <peter@hatina.eu>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>

tests/test_environment_variables.py

@@ -0,0 +1,30 @@
+import os
+import shutil
+from kas import kas
+
+
+def test_build_dir_is_placed_inside_work_dir_by_default(changedir, tmpdir):
+    conf_dir = str(tmpdir.mkdir('test_env_variables'))
+    shutil.rmtree(conf_dir, ignore_errors=True)
+    shutil.copytree('tests/test_environment_variables', conf_dir)
+
+    os.chdir(conf_dir)
+
+    kas.kas(['checkout', 'test.yml'])
+
+    assert(os.path.exists(os.path.join(os.getcwd(), 'build', 'conf')))
+
+
+def test_build_dir_can_be_specified_by_environment_variable(changedir, tmpdir):
+    conf_dir = str(tmpdir.mkdir('test_env_variables'))
+    build_dir = str(tmpdir.mkdir('test_build_dir'))
+    shutil.rmtree(conf_dir, ignore_errors=True)
+    shutil.copytree('tests/test_environment_variables', conf_dir)
+    shutil.rmtree(build_dir, ignore_errors=True)
+    os.chdir(conf_dir)
+
+    os.environ['KAS_BUILD_DIR'] = build_dir
+    kas.kas(['checkout', 'test.yml'])
+    del os.environ['KAS_BUILD_DIR']
+
+    assert(os.path.exists(os.path.join(build_dir, 'conf')))

tests/test_environment_variables/oe-init-build-env

@@ -0,0 +1,3 @@
+#!/bin/sh
+
+true

tests/test_environment_variables/test.yml

@@ -0,0 +1,5 @@
+header:
+  version: 10
+
+repos:
+  this: