Allow formatting tags on a single line

Add a --single-line-tags option, which causes consecutive tags to be
output on a single line. Also add a --multi-line-tags option to
explicitly specify the current default behaviour of outputting one tag
per line.

When the --single-line-tags option is specified, tags separated by
comments are merged into one line, as discussed in issue #22.

reformat_gherkin/ast_node/__init__.py

@@ -14,6 +14,7 @@
 from .table_cell import TableCell
 from .table_row import TableRow
 from .tag import Tag
+from .tag_group import TagGroup
 
 Node = Union[
     Background,
@@ -30,4 +31,5 @@
     TableCell,
     TableRow,
     Tag,
+    TagGroup,
 ]

reformat_gherkin/ast_node/tag_group.py

@@ -0,0 +1,15 @@
+from typing import Tuple, Union
+
+from ._base import prepare
+from .examples import Examples
+from .feature import Feature
+from .location import LocationMixin
+from .scenario import Scenario
+from .scenario_outline import ScenarioOutline
+from .tag import Tag
+
+
+@prepare
+class TagGroup(LocationMixin):
+    members: Tuple[Tag, ...]
+    context: Union[Examples, Feature, Scenario, ScenarioOutline]

reformat_gherkin/cli.py

@@ -5,7 +5,7 @@
 from .config import read_config_file
 from .core import reformat
 from .errors import EmptySources
-from .options import AlignmentMode, NewlineMode, Options, WriteBackMode
+from .options import AlignmentMode, NewlineMode, Options, TagLineMode, WriteBackMode
 from .report import Report
 from .utils import out
 from .version import __version__
@@ -55,6 +55,16 @@
     is_flag=True,
     help="If --fast given, skip the sanity checks of file contents. [default: --safe]",
 )
+@click.option(
+    "--single-line-tags/--multi-line-tags",
+    is_flag=True,
+    default=False,
+    help=(
+        "If --single-line-tags given, output consecutive tags on one line. "
+        "If --multi-line-tags given, output one tag per line. "
+        "[default: --multi-line-tags]"
+    ),
+)
 @click.option(
     "--config",
     type=click.Path(
@@ -73,6 +83,7 @@ def main(
     alignment: Optional[str],
     newline: Optional[str],
     fast: bool,
+    single_line_tags: bool,
     config: Optional[str],
 ) -> None:
     """
@@ -84,12 +95,14 @@ def main(
     write_back_mode = WriteBackMode.from_configuration(check)
     alignment_mode = AlignmentMode.from_configuration(alignment)
     newline_mode = NewlineMode.from_configuration(newline)
+    tag_line_mode = TagLineMode.from_configuration(single_line_tags)
 
     options = Options(
         write_back=write_back_mode,
         step_keyword_alignment=alignment_mode,
         newline=newline_mode,
         fast=fast,
+        tag_line_mode=tag_line_mode,
     )
 
     report = Report(check=check)

reformat_gherkin/core.py

@@ -106,7 +106,9 @@ def format_str(src_contents: str, *, options: Options) -> str:
     """
     ast = parse(src_contents)
 
-    line_generator = LineGenerator(ast, options.step_keyword_alignment)
+    line_generator = LineGenerator(
+        ast, options.step_keyword_alignment, options.tag_line_mode
+    )
     lines = line_generator.generate()
 
     return "\n".join(lines)

reformat_gherkin/formatter.py

@@ -1,5 +1,5 @@
 from itertools import chain, zip_longest
-from typing import Any, Dict, Iterator, List, Mapping, Optional, Set, Union
+from typing import Any, Dict, Iterator, List, Mapping, Optional, Set, Tuple, Union
 
 from attr import attrib, dataclass
 
@@ -18,8 +18,9 @@
     Step,
     TableRow,
     Tag,
+    TagGroup,
 )
-from .options import AlignmentMode
+from .options import AlignmentMode, TagLineMode
 from .utils import (
     camel_to_snake_case,
     extract_beginning_spaces,
@@ -184,25 +185,50 @@ def generate_doc_string_lines(docstring: DocString) -> List[str]:
     return [f"{INDENT * indent_level}{line}" for line in raw_lines]
 
 
-ContextMap = Dict[Union[Comment, Tag, TableRow], Any]
+ContextMap = Dict[Union[Comment, Tag, TagGroup, TableRow], Any]
 Lines = Iterator[str]
 
 
 @dataclass
 class LineGenerator:
     ast: GherkinDocument
     step_keyword_alignment: AlignmentMode
+    tag_line_mode: TagLineMode
     __nodes: List[Node] = attrib(init=False)
     __contexts: ContextMap = attrib(init=False)
     __nodes_with_newline: Set[Node] = attrib(init=False)
+    __tag_groups: List[TagGroup] = attrib(factory=list)
 
     def __attrs_post_init__(self):
         # Use `__attrs_post_init__` instead of `property` to avoid re-computing attributes
-        self.__nodes = sorted(list(self.ast), key=lambda node: node.location)
+
+        if self.tag_line_mode is TagLineMode.SINGLELINE:
+            self.__group_tags()
+
+        self.__nodes = sorted(
+            list(self.ast) + self.__tag_groups, key=lambda node: node.location
+        )
+
         self.__contexts = self.__construct_contexts()
         self.__nodes_with_newline = self.__find_nodes_with_newline()
         self.__add_language_header()
 
+    def __group_tags(self):
+        """
+        Group the tags of a node, so that we can render them on a single line.
+        """
+        node: Node
+        for node in self.ast:
+            if hasattr(node, "tags"):
+                tags: Tuple[Tag, ...] = node.tags
+
+                if tags:
+                    # The tag group should be placed at the position of the last tag
+                    tag_group = TagGroup(
+                        members=tags, context=node, location=tags[-1].location
+                    )
+                    self.__tag_groups.append(tag_group)
+
     def __construct_contexts(self) -> ContextMap:
         """
         Construct the information about the context a certain line might need to know to
@@ -212,6 +238,9 @@ def __construct_contexts(self) -> ContextMap:
         nodes = self.__nodes
 
         for node in nodes:
+            if hasattr(node, "context"):
+                contexts[node] = node.context  # type: ignore
+
             # We want tags to have the same indentation level with their parents
             for tag in getattr(node, "tags", []):
                 contexts[tag] = node
@@ -286,6 +315,9 @@ def __add_language_header(self) -> None:
 
     def generate(self) -> Lines:
         for node in self.__nodes:
+            if self.tag_line_mode is TagLineMode.SINGLELINE and isinstance(node, Tag):
+                continue
+
             yield from self.visit(node)
 
             if node in self.__nodes_with_newline:
@@ -324,6 +356,15 @@ def visit_tag(self, tag: Tag) -> Lines:
 
         yield f"{INDENT * indent_level}{tag.name}"
 
+    def visit_tag_group(self, tag_group: TagGroup) -> Lines:
+        context = self.__contexts[tag_group]
+
+        indent_level = INDENT_LEVEL_MAP[type(context)]
+
+        line_content = " ".join(tag.name for tag in tag_group.members)
+
+        yield f"{INDENT * indent_level}{line_content}"
+
     def visit_table_row(self, row: TableRow) -> Lines:
         context = self.__contexts[row]
 

reformat_gherkin/options.py

@@ -36,9 +36,20 @@ def from_configuration(cls, newline: Optional[str]) -> "NewlineMode":
         return NewlineMode(newline)
 
 
+@unique
+class TagLineMode(Enum):
+    SINGLELINE = "singleline"
+    MULTILINE = "multiline"
+
+    @classmethod
+    def from_configuration(cls, single_line_tags: bool) -> "TagLineMode":
+        return TagLineMode.SINGLELINE if single_line_tags else TagLineMode.MULTILINE
+
+
 @dataclass(frozen=True)
 class Options:
     write_back: WriteBackMode
     step_keyword_alignment: AlignmentMode
     newline: NewlineMode
+    tag_line_mode: TagLineMode
     fast: bool

tests/data/valid/full/expected_single_line_tags.feature

@@ -0,0 +1,53 @@
+@tag-1 @tag-2
+Feature: Some meaningful feature
+  Some meaningful feature description
+
+  Background: A solid background
+    Some description for this background
+      This description has multiple lines
+
+    Given A lot of money
+      | EUR |
+      | USD |
+      | VND |
+
+  @tag-no-1 @decorate-1 @fixture-1
+  Scenario: Gain a lot of money
+    This is a description for this scenario
+
+    Given I go to the bank
+    Then I rob the bank
+
+  # Some comment here...
+  @tag-no-2 @decorate-2 @prepare-2 @fixture-2
+  # Another comment...
+  Scenario Outline: Break the bank's vault
+    A description for this scenario outline
+
+    # Is it helpful to put a comment here?
+    Given I stand in front of the bank's vault
+    And I break the vault's door
+    """
+    Some docstring here
+      A docstring can have multiple lines
+        With indentation
+    """
+    Then I enter the vault
+    """
+    Some docstring there
+    """
+    And I see a lot of money
+
+    # Examples can have tags? Hmmm...
+    @test-examples-tags
+    Examples: Continents
+      This is the description for these examples
+
+      | Asia    | 111 |
+      | Europe  | 22  |
+      # We can even have a comment in the middle of a table
+      | America | 3   |
+      # Pipe characters in table cells need to be escaped
+      | a \| b  | 4   |
+
+# Some random comment at the end of the document

tests/helpers.py

@@ -1,22 +1,34 @@
-from reformat_gherkin.options import AlignmentMode, NewlineMode, Options, WriteBackMode
-
-
-def make_options(alignment_mode):
+from reformat_gherkin.options import (
+    AlignmentMode,
+    NewlineMode,
+    Options,
+    TagLineMode,
+    WriteBackMode,
+)
+
+
+def make_options(
+    *, step_keyword_alignment=AlignmentMode.NONE, tag_line_mode=TagLineMode.MULTILINE
+):
     return Options(
         write_back=WriteBackMode.CHECK,
-        step_keyword_alignment=alignment_mode,
+        step_keyword_alignment=step_keyword_alignment,
         newline=NewlineMode.KEEP,
+        tag_line_mode=tag_line_mode,
         fast=False,
     )
 
 
-OPTIONS = [make_options(alignment_mode) for alignment_mode in AlignmentMode]
-
+OPTIONS = [
+    make_options(step_keyword_alignment=alignment_mode)
+    for alignment_mode in AlignmentMode
+]
 
 FILENAME_OPTION_MAP = {
-    "expected_default": make_options(AlignmentMode.NONE),
-    "expected_left_aligned": make_options(AlignmentMode.LEFT),
-    "expected_right_aligned": make_options(AlignmentMode.RIGHT),
+    "expected_default": make_options(step_keyword_alignment=AlignmentMode.NONE),
+    "expected_left_aligned": make_options(step_keyword_alignment=AlignmentMode.LEFT),
+    "expected_right_aligned": make_options(step_keyword_alignment=AlignmentMode.RIGHT),
+    "expected_single_line_tags": make_options(tag_line_mode=TagLineMode.SINGLELINE),
 }
 
 

tests/test_formatter.py

@@ -1,6 +1,6 @@
 from reformat_gherkin.ast_node import GherkinDocument
 from reformat_gherkin.formatter import INDENT_LEVEL_MAP, LineGenerator
-from reformat_gherkin.options import AlignmentMode
+from reformat_gherkin.options import AlignmentMode, TagLineMode
 
 
 def verify_indent_level_map():
@@ -20,8 +20,10 @@ def verify_indent_level_map():
             assert node_type in INDENT_LEVEL_MAP
 
 
-def format_ast(ast, alignment_mode=AlignmentMode.LEFT):
-    line_generator = LineGenerator(ast, alignment_mode)
+def format_ast(
+    ast, alignment_mode=AlignmentMode.LEFT, tag_line_mode=TagLineMode.MULTILINE
+):
+    line_generator = LineGenerator(ast, alignment_mode, tag_line_mode)
     lines = line_generator.generate()
     return "\n".join(lines)