tests/test_target: Read target connection settings from a YAML file

This will be useful in automating CI tests without modifying the source
code.

Also fix pylint issues.

Signed-off-by: Metin Kaya <metin.kaya@arm.com>

Author: metin-arm

tests/target_configs.yaml

@@ -0,0 +1,4 @@
+LocalLinuxTarget:
+  connection_settings:
+    unrooted: True
+

tests/test_target.py

@@ -14,17 +14,30 @@
 # limitations under the License.
 #
 
+''' Module for testing targets. '''
+
 import os
 import shutil
 import tempfile
 from unittest import TestCase
 
 from devlib import LocalLinuxTarget
+from devlib.utils.misc import load_struct_from_yaml
 
 
 class TestReadTreeValues(TestCase):
+    ''' Class testing Target.read_tree_values_flat() '''
+
+    TARGETS_CONFIG_FILE = 'tests/target_configs.yaml'
 
     def test_read_multiline_values(self):
+        ''' Test Target.read_tree_values_flat() '''
+
+        target_configs = load_struct_from_yaml(self.TARGETS_CONFIG_FILE)
+        if target_configs is None or target_configs.get('LocalLinuxTarget') is None:
+            print(f'No target(s) specified in {self.TARGETS_CONFIG_FILE}!')
+            return
+
         data = {
             'test1': '1',
             'test2': '2\n\n',
@@ -34,11 +47,13 @@ def test_read_multiline_values(self):
         tempdir = tempfile.mkdtemp(prefix='devlib-test-')
         for key, value in data.items():
             path = os.path.join(tempdir, key)
-            with open(path, 'w') as wfh:
+            with open(path, 'w', encoding='utf-8') as wfh:
                 wfh.write(value)
 
-        t = LocalLinuxTarget(connection_settings={'unrooted': True})
-        raw_result = t.read_tree_values_flat(tempdir)
+        target = LocalLinuxTarget(
+            connection_settings=target_configs['LocalLinuxTarget']['connection_settings'],
+        )
+        raw_result = target.read_tree_values_flat(tempdir)
         result = {os.path.basename(k): v for k, v in raw_result.items()}
 
         shutil.rmtree(tempdir)