feat(history): support linking compare page in changelog

Fixes #218

semantic_release/cli.py

@@ -248,7 +248,10 @@ def publish(**kwargs):
                     owner,
                     name,
                     new_version,
-                    markdown_changelog(new_version, log, header=False),
+                    markdown_changelog(
+                        new_version, log, header=False,
+                        previous_version=current_version
+                    ),
                 )
             except GitError:
                 logger.error("Posting changelog failed")

semantic_release/defaults.cfg

@@ -15,3 +15,4 @@ remove_dist=true
 build_command=python setup.py sdist bdist_wheel
 branch=master
 changelog_sections=feature,fix,breaking,documentation,performance
+compare_link=false

semantic_release/history/logs.py

@@ -6,7 +6,7 @@
 from ..errors import UnknownCommitMessageStyleError
 from ..helpers import LoggedFunction
 from ..settings import config, current_commit_parser
-from ..vcs_helpers import get_commit_log
+from ..vcs_helpers import get_commit_log, get_repository_owner_and_name
 from .parser_helpers import re_breaking
 
 logger = logging.getLogger(__name__)
@@ -160,12 +160,29 @@ def generate_changelog(from_version: str, to_version: str = None) -> dict:
     return changes
 
 
+def get_github_compare_url(from_version: str, to_version: str) -> str:
+    """
+    Get the GitHub comparison link between two version tags.
+
+    :param from_version: The older version to compare.
+    :param to_version: The newer version to compare.
+    :return: Link to view a comparison between the two versions.
+    """
+    owner, name = get_repository_owner_and_name()
+    return (
+        f"https://github.com/{owner}/{name}"
+        f"/compare/v{from_version}...v{to_version}"
+    )
+
+
 @LoggedFunction(logger)
-def markdown_changelog(version: str, changelog: dict, header: bool = False) -> str:
+def markdown_changelog(version: str, changelog: dict, header: bool = False, previous_version: str = None) -> str:
     """
     Generate a markdown version of the changelog.
 
     :param version: A string with the version number.
+    :param previous_version: A string with the last version number, to
+        use for the comparison URL. If omitted, the URL will not be included.
     :param changelog: A parsed changelog dict from generate_changelog.
     :param header: A boolean that decides whether a version number header should be included.
     :return: The markdown formatted changelog.
@@ -175,6 +192,14 @@ def markdown_changelog(version: str, changelog: dict, header: bool = False) -> s
         # Add a heading with the version number
         output += "## v{0}\n".format(version)
 
+    if (
+        config.getboolean("semantic_release", "compare_link")
+        and config.get("semantic_release", "hvcs").lower() == 'github'
+        and previous_version
+    ):
+        compare_url = get_github_compare_url(previous_version, version)
+        output += f"**[See all commits in this version]({compare_url})**\n"
+
     # Sections which will be shown in the Markdown changelog.
     # This is NOT related to supported commit types.
     changelog_sections = config.get("semantic_release", "changelog_sections")

tests/history/test_markdown_changelog.py

@@ -1,4 +1,17 @@
-from semantic_release.history.logs import markdown_changelog
+import mock
+
+from semantic_release.history.logs import markdown_changelog, get_github_compare_url
+
+
+def test_github_compare_url():
+    with mock.patch(
+        'semantic_release.history.logs.get_repository_owner_and_name',
+        return_value=['owner', 'name']
+    ):
+        assert (
+            get_github_compare_url('1.0.0', '2.0.0') ==
+            "https://github.com/owner/name/compare/v1.0.0...v2.0.0"
+        )
 
 
 def test_should_output_all_sections():
@@ -78,3 +91,31 @@ def test_should_output_heading():
         },
         header=True,
     )
+
+
+def test_compare_url(mocker):
+    mocker.patch(
+        'semantic_release.history.logs.config.getboolean',
+        return_value=True
+    )
+    mocker.patch(
+        'semantic_release.history.logs.get_repository_owner_and_name',
+        return_value=['owner', 'name']
+    )
+
+    assert (
+        "**[See all commits in this version]"
+        "(https://github.com/owner/name/compare/v1.0.0...v2.0.0)**\n"
+        in markdown_changelog(
+            "2.0.0",
+            {
+                "refactor": [],
+                "breaking": [],
+                "feature": [],
+                "fix": [],
+                "documentation": [],
+                "performance": [],
+            },
+            previous_version="1.0.0",
+        )
+    )

tests/test_cli.py

@@ -514,7 +514,10 @@ def test_publish_giterror_when_posting(mocker):
     )
     mock_check_token.assert_called_once_with()
     mock_generate.assert_called_once_with("current", "new")
-    mock_markdown.assert_called_once_with("new", "super changelog", header=False)
+    mock_markdown.assert_called_once_with(
+        "new", "super changelog",
+        header=False, previous_version='current'
+    )
     mock_post.assert_called_once_with("owner", "name", "new", "super md changelog")