Fix typos and format of LoadTest generator output. (#26149)

This change fixes typos and makes minor changes to the format of the generated yaml files for LoadTest configuration (embedded scenarios end in newline, and element lists are indented). The templates generated earlier are also updated.

tools/run_tests/performance/README.md

@@ -29,8 +29,8 @@ server, it might be useful to run workers manually.
 2. Connect to each worker machine and start up a benchmark worker with a
    "driver_port".
 
-- For example, to start the grpc-go benchmark worker: [grpc-go worker
-  main.go](https://github.com/grpc/grpc-go/blob/master/benchmark/worker/main.go)
+- For example, to start the grpc-go benchmark worker:
+  [grpc-go worker main.go](https://github.com/grpc/grpc-go/blob/master/benchmark/worker/main.go)
   --driver_port <driver_port>
 
 #### Commands to start workers in different languages:
@@ -347,7 +347,7 @@ $ ./tools/run_tests/performance/loadtest_template.py \
     --name basic_all_languages
 ```
 
-The script `loadest_template.py` takes the following options:
+The script `loadtest_template.py` takes the following options:
 
 - `-i`, `--inputs`<br> Space-separated list of the names of input files
   containing LoadTest configurations. May be repeated.

tools/run_tests/performance/loadtest_config.py

@@ -150,7 +150,8 @@ def gen_loadtest_configs(
             uniq = (uniquifier_elements +
                     [run_index] if run_index else uniquifier_elements)
             name = loadtest_name(prefix, scenario['name'], uniq)
-            scenario_str = json.dumps({'scenarios': scenario}, indent='  ')
+            scenario_str = json.dumps({'scenarios': scenario},
+                                      indent='  ') + '\n'
 
             config = copy.deepcopy(base_config)
 
@@ -206,7 +207,7 @@ def parse_key_value_args(args: Optional[Iterable[str]]) -> Dict[str, str]:
     return d
 
 
-def config_dumper(header_comment: str) -> Type[yaml.Dumper]:
+def config_dumper(header_comment: str) -> Type[yaml.SafeDumper]:
     """Returns a custom dumper to dump configurations in the expected format."""
 
     class ConfigDumper(yaml.SafeDumper):
@@ -217,6 +218,15 @@ def config_dumper(header_comment: str) -> Type[yaml.Dumper]:
                 self.write_indent()
                 self.write_indicator(header_comment, need_whitespace=False)
 
+        def expect_block_sequence(self):
+            super().expect_block_sequence()
+            self.increase_indent()
+
+        def expect_block_sequence_item(self, first=False):
+            if isinstance(self.event, yaml.SequenceEndEvent):
+                self.indent = self.indents.pop()
+            super().expect_block_sequence_item(first)
+
     def str_presenter(dumper, data):
         if '\n' in data:
             return dumper.represent_scalar('tag:yaml.org,2002:str',
@@ -266,7 +276,7 @@ def main() -> None:
     argp.add_argument(
         '-d',
         action='store_true',
-        help='Use creation date and time as an addditional uniquifier element.')
+        help='Use creation date and time as an additional uniquifier element.')
     argp.add_argument('-a',
                       '--annotation',
                       action='append',

tools/run_tests/performance/loadtest_template.py

@@ -122,7 +122,7 @@ def loadtest_template(
     return template
 
 
-def template_dumper(header_comment: str) -> Type[yaml.Dumper]:
+def template_dumper(header_comment: str) -> Type[yaml.SafeDumper]:
     """Returns a custom dumper to dump templates in the expected format."""
 
     class TemplateDumper(yaml.SafeDumper):
@@ -133,6 +133,15 @@ def template_dumper(header_comment: str) -> Type[yaml.Dumper]:
                 self.write_indent()
                 self.write_indicator(header_comment, need_whitespace=False)
 
+        def expect_block_sequence(self):
+            super().expect_block_sequence()
+            self.increase_indent()
+
+        def expect_block_sequence_item(self, first=False):
+            if isinstance(self.event, yaml.SequenceEndEvent):
+                self.indent = self.indents.pop()
+            super().expect_block_sequence_item(first)
+
     return TemplateDumper