diff --git a/rsmtool/rsmcompare.py b/rsmtool/rsmcompare.py
index 58158171..903999fc 100644
--- a/rsmtool/rsmcompare.py
+++ b/rsmtool/rsmcompare.py
@@ -178,7 +178,7 @@ def run_comparison(config_file_or_obj_or_dict, output_dir):
     )
 
 
-def main():  # noqa: D103
+def main(argv=None):  # noqa: D103
     # set up the basic logging configuration
     formatter = LogFormatter()
 
@@ -200,22 +200,25 @@ def main():  # noqa: D103
     parser = setup_rsmcmd_parser("rsmcompare", uses_output_directory=True, uses_subgroups=True)
 
     # if we have no arguments at all then just show the help message
-    if len(sys.argv) < 2:
-        sys.argv.append("-h")
+    if argv is None:
+        argv = sys.argv
+
+    if len(argv) < 2:
+        argv.append("-h")
 
     # if the first argument is not one of the valid sub-commands
     # or one of the valid optional arguments, then assume that they
     # are arguments for the "run" sub-command. This allows the
     # old style command-line invocations to work without modification.
-    if sys.argv[1] not in VALID_PARSER_SUBCOMMANDS + [
+    if argv[0] not in VALID_PARSER_SUBCOMMANDS + [
         "-h",
         "--help",
         "-V",
         "--version",
     ]:
-        args_to_pass = ["run"] + sys.argv[1:]
+        args_to_pass = ["run"] + argv
     else:
-        args_to_pass = sys.argv[1:]
+        args_to_pass = argv
     args = parser.parse_args(args=args_to_pass)
 
     # call the appropriate function based on which sub-command was run
diff --git a/rsmtool/rsmeval.py b/rsmtool/rsmeval.py
index 930b38ca..81c1be72 100644
--- a/rsmtool/rsmeval.py
+++ b/rsmtool/rsmeval.py
@@ -219,7 +219,7 @@ def run_evaluation(
     reporter.create_report(pred_analysis_config, csvdir, figdir, context="rsmeval")
 
 
-def main():  # noqa: D103
+def main(argv=None):  # noqa: D103
     # set up the basic logging configuration
     formatter = LogFormatter()
 
@@ -246,22 +246,25 @@ def main():  # noqa: D103
     )
 
     # if we have no arguments at all then just show the help message
-    if len(sys.argv) < 2:
-        sys.argv.append("-h")
+    if argv is None:
+        argv = sys.argv
+
+    if len(argv) < 2:
+        argv.append("-h")
 
     # if the first argument is not one of the valid sub-commands
     # or one of the valid optional arguments, then assume that they
     # are arguments for the "run" sub-command. This allows the
     # old style command-line invocations to work without modification.
-    if sys.argv[1] not in VALID_PARSER_SUBCOMMANDS + [
+    if argv[0] not in VALID_PARSER_SUBCOMMANDS + [
         "-h",
         "--help",
         "-V",
         "--version",
     ]:
-        args_to_pass = ["run"] + sys.argv[1:]
+        args_to_pass = ["run"] + argv
     else:
-        args_to_pass = sys.argv[1:]
+        args_to_pass = argv
     args = parser.parse_args(args=args_to_pass)
 
     # call the appropriate function based on which sub-command was run
diff --git a/rsmtool/rsmexplain.py b/rsmtool/rsmexplain.py
index c4010516..8f77062e 100644
--- a/rsmtool/rsmexplain.py
+++ b/rsmtool/rsmexplain.py
@@ -525,7 +525,7 @@ def generate_report(explanation, output_dir, ids, configuration, logger=None, wa
     reporter.create_explanation_report(configuration, csvdir, reportdir)
 
 
-def main():
+def main(argv=None):  # noqa: D103
     """Run rsmexplain and generate explanation reports."""
     # set up the basic logging configuration
     formatter = LogFormatter()
@@ -545,23 +545,26 @@ def main():
     # set up an argument parser via our helper function
     parser = setup_rsmcmd_parser("rsmexplain", uses_output_directory=True, allows_overwriting=True)
 
-    # if no arguments provided then just show the help message
-    if len(sys.argv) < 2:
-        sys.argv.append("-h")
+    # if we have no arguments at all then just show the help message
+    if argv is None:
+        argv = sys.argv
+
+    if len(argv) < 2:
+        argv.append("-h")
 
     # if the first argument is not one of the valid sub-commands
     # or one of the valid optional arguments, then assume that they
     # are arguments for the "run" sub-command. This allows the
     # old style command-line invocations to work without modification.
-    if sys.argv[1] not in VALID_PARSER_SUBCOMMANDS + [
+    if argv[0] not in VALID_PARSER_SUBCOMMANDS + [
         "-h",
         "--help",
         "-V",
         "--version",
     ]:
-        args_to_pass = ["run"] + sys.argv[1:]
+        args_to_pass = ["run"] + argv
     else:
-        args_to_pass = sys.argv[1:]
+        args_to_pass = argv
     args = parser.parse_args(args=args_to_pass)
 
     if args.subcommand == "run":
diff --git a/rsmtool/rsmpredict.py b/rsmtool/rsmpredict.py
index eb697f37..dc8b026d 100644
--- a/rsmtool/rsmpredict.py
+++ b/rsmtool/rsmpredict.py
@@ -505,7 +505,7 @@ def compute_and_save_predictions(
         )
 
 
-def main():  # noqa: D103
+def main(argv=None):  # noqa: D103
     # set up the basic logging configuration
     formatter = LogFormatter()
 
@@ -540,22 +540,25 @@ def main():  # noqa: D103
     )
 
     # if we have no arguments at all then just show the help message
-    if len(sys.argv) < 2:
-        sys.argv.append("-h")
+    if argv is None:
+        argv = sys.argv
+
+    if len(argv) < 2:
+        argv.append("-h")
 
     # if the first argument is not one of the valid sub-commands
     # or one of the valid optional arguments, then assume that they
     # are arguments for the "run" sub-command. This allows the
     # old style command-line invocations to work without modification.
-    if sys.argv[1] not in VALID_PARSER_SUBCOMMANDS + [
+    if argv[0] not in VALID_PARSER_SUBCOMMANDS + [
         "-h",
         "--help",
         "-V",
         "--version",
     ]:
-        args_to_pass = ["run"] + sys.argv[1:]
+        args_to_pass = ["run"] + argv
     else:
-        args_to_pass = sys.argv[1:]
+        args_to_pass = argv
     args = parser.parse_args(args=args_to_pass)
 
     # call the appropriate function based on which sub-command was run
diff --git a/rsmtool/rsmsummarize.py b/rsmtool/rsmsummarize.py
index da4c8fe8..7a2efb02 100644
--- a/rsmtool/rsmsummarize.py
+++ b/rsmtool/rsmsummarize.py
@@ -235,7 +235,7 @@ def run_summary(
     reporter.create_summary_report(configuration, all_experiments, csvdir)
 
 
-def main():  # noqa: D103
+def main(argv=None):  # noqa: D103
     # set up the basic logging configuration
     formatter = LogFormatter()
 
@@ -259,22 +259,25 @@ def main():  # noqa: D103
     )
 
     # if we have no arguments at all then just show the help message
-    if len(sys.argv) < 2:
-        sys.argv.append("-h")
+    if argv is None:
+        argv = sys.argv
+
+    if len(argv) < 2:
+        argv.append("-h")
 
     # if the first argument is not one of the valid sub-commands
     # or one of the valid optional arguments, then assume that they
     # are arguments for the "run" sub-command. This allows the
     # old style command-line invocations to work without modification.
-    if sys.argv[1] not in VALID_PARSER_SUBCOMMANDS + [
+    if argv[0] not in VALID_PARSER_SUBCOMMANDS + [
         "-h",
         "--help",
         "-V",
         "--version",
     ]:
-        args_to_pass = ["run"] + sys.argv[1:]
+        args_to_pass = ["run"] + argv
     else:
-        args_to_pass = sys.argv[1:]
+        args_to_pass = argv
     args = parser.parse_args(args=args_to_pass)
 
     # call the appropriate function based on which sub-command was run
diff --git a/rsmtool/rsmtool.py b/rsmtool/rsmtool.py
index f68c8d7a..3ac2d688 100644
--- a/rsmtool/rsmtool.py
+++ b/rsmtool/rsmtool.py
@@ -347,7 +347,7 @@ def run_experiment(
     reporter.create_report(pred_analysis_config, csvdir, figdir)
 
 
-def main():  # noqa: D103
+def main(argv=None):  # noqa: D103
     # set up the basic logging configuration
     formatter = LogFormatter()
 
@@ -374,22 +374,25 @@ def main():  # noqa: D103
     )
 
     # if we have no arguments at all then just show the help message
-    if len(sys.argv) < 2:
-        sys.argv.append("-h")
+    if argv is None:
+        argv = sys.argv
+
+    if len(argv) < 2:
+        argv.append("-h")
 
     # if the first argument is not one of the valid sub-commands
     # or one of the valid optional arguments, then assume that they
     # are arguments for the "run" sub-command. This allows the
     # old style command-line invocations to work without modification.
-    if sys.argv[1] not in VALID_PARSER_SUBCOMMANDS + [
+    if argv[0] not in VALID_PARSER_SUBCOMMANDS + [
         "-h",
         "--help",
         "-V",
         "--version",
     ]:
-        args_to_pass = ["run"] + sys.argv[1:]
+        args_to_pass = ["run"] + argv
     else:
-        args_to_pass = sys.argv[1:]
+        args_to_pass = argv
     args = parser.parse_args(args=args_to_pass)
 
     # call the appropriate function based on which sub-command was run
diff --git a/rsmtool/rsmxval.py b/rsmtool/rsmxval.py
index d687b1dc..3d23d226 100644
--- a/rsmtool/rsmxval.py
+++ b/rsmtool/rsmxval.py
@@ -268,7 +268,7 @@ def run_cross_validation(
     )
 
 
-def main():  # noqa: D103
+def main(argv=None):  # noqa: D103
     # set up the basic logging configuration
     formatter = LogFormatter()
 
@@ -295,22 +295,25 @@ def main():  # noqa: D103
     )
 
     # if we have no arguments at all then just show the help message
-    if len(sys.argv) < 2:
-        sys.argv.append("-h")
+    if argv is None:
+        argv = sys.argv
+
+    if len(argv) < 2:
+        argv.append("-h")
 
     # if the first argument is not one of the valid sub-commands
     # or one of the valid optional arguments, then assume that they
     # are arguments for the "run" sub-command. This allows the
     # old style command-line invocations to work without modification.
-    if sys.argv[1] not in VALID_PARSER_SUBCOMMANDS + [
+    if argv[0] not in VALID_PARSER_SUBCOMMANDS + [
         "-h",
         "--help",
         "-V",
         "--version",
     ]:
-        args_to_pass = ["run"] + sys.argv[1:]
+        args_to_pass = ["run"] + argv
     else:
-        args_to_pass = sys.argv[1:]
+        args_to_pass = argv
     args = parser.parse_args(args=args_to_pass)
 
     # call the appropriate function based on which sub-command was run