to open expected outpout file with an encoding parameter

launch_testing/launch_testing/tools/output.py

@@ -14,6 +14,7 @@
 
 import os
 import re
+from typing import Optional
 
 from osrf_pycommon.terminal_color import remove_ansi_escape_sequences
 
@@ -64,21 +65,22 @@ def _filter(output):
     return _filter
 
 
-def expected_output_from_file(path):
+def expected_output_from_file(path: str, encoding: Optional[str] = None):
     """
     Get expected output lines from a file.
 
     :param path: path w/o extension of either a .txt file containing the lines
     to be matched or a .regex file containing patterns to be searched for.
+    :param encoding: the character encoding to be used when opening the file.
     """
     literal_file = path + '.txt'
     if os.path.isfile(literal_file):
-        with open(literal_file, 'r') as f:
+        with open(literal_file, 'r', encoding=encoding) as f:
             return f.read().splitlines()
 
     regex_file = path + '.regex'
     if os.path.isfile(regex_file):
-        with open(regex_file, 'r') as f:
+        with open(regex_file, 'r', encoding=encoding) as f:
             return [re.compile(regex) for regex in f.read().splitlines()]
 
     raise RuntimeError('could not find output check file: {}'.format(path))

launch_testing/test/launch_testing/test_tools.py

@@ -12,6 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import os
 import re
 
 import launch.actions
@@ -22,6 +23,7 @@
 
 from launch_testing.tools import basic_output_filter
 from launch_testing.tools import expect_output
+from launch_testing.tools import expected_output_from_file
 from launch_testing.tools import ProcessProxy
 
 
@@ -95,6 +97,38 @@ def test_expect_output():
     )
 
 
+def test_expected_output_from_file():
+    # to test txt file
+    output_text = 'test\btest'
+    name = 'test_tools_expected_output_from_txt_file'
+    # use the default encoding parameter
+    expected_output = expected_output_from_file(
+                        path=os.path.join(os.path.dirname(__file__), name)
+                    )
+    assert not expect_output(expected_lines=expected_output, text=output_text)
+    # use the encoding parameter with 'unicode_escape'
+    expected_output = expected_output_from_file(
+                        path=os.path.join(os.path.dirname(__file__), name),
+                        encoding='unicode_escape'
+                    )
+    assert expect_output(expected_lines=expected_output, text=output_text)
+
+    # to test regex file
+    output_text = 'test\btestaaaaa'
+    name = 'test_tools_expected_output_from_regex_file'
+    # use the default encoding parameter
+    expected_output = expected_output_from_file(
+                        path=os.path.join(os.path.dirname(__file__), name)
+                    )
+    assert not expect_output(expected_lines=expected_output, text=output_text)
+    # use the encoding parameter with 'unicode_escape'
+    expected_output = expected_output_from_file(
+                        path=os.path.join(os.path.dirname(__file__), name),
+                        encoding='unicode_escape'
+                    )
+    assert expect_output(expected_lines=expected_output, text=output_text)
+
+
 def test_process_proxy():
     proc_output = launch_testing.io_handler.ActiveIoHandler()
     proc_info = launch_testing.proc_info_handler.ActiveProcInfoHandler()

launch_testing/test/launch_testing/test_tools_expected_output_from_regex_file.regex

@@ -0,0 +1 @@
+test\btesta{5}

launch_testing/test/launch_testing/test_tools_expected_output_from_txt_file.txt

@@ -0,0 +1 @@
+test\btest