Calculate PR-style diff

README.md

@@ -116,6 +116,10 @@ jobs:
       contents: write
     steps:
       - uses: actions/checkout@v4
+        with:
+          # New lines are discovered by running a three-dot notation diff on base_ref...head. They must share a common
+          # ancestor. Setting fetch-depth to 1000 here should ensure that.
+          fetch-depth: 1000
 
       - name: Install everything, run the tests, produce the .coverage file
         run: make test # This is the part where you put your own test command
@@ -205,6 +209,8 @@ jobs:
       contents: write
     steps:
       - uses: actions/checkout@v4
+        with:
+          fetch-depth: 1000
 
       - name: Install everything, run the tests, produce the .coverage file
         run: make test # This is the part where you put your own test command
@@ -247,6 +253,8 @@ jobs:
 
     steps:
       - uses: actions/checkout@v4
+        with:
+          fetch-depth: 1000
 
       - name: Set up Python
         id: setup-python
@@ -284,6 +292,8 @@ jobs:
       contents: write
     steps:
       - uses: actions/checkout@v4
+        with:
+          fetch-depth: 1000
 
       - uses: actions/download-artifact@v4
         id: download

coverage_comment/coverage.py

@@ -293,7 +293,7 @@ def get_added_lines(
     # don't merge chunks. This means the headers that describe line number
     # are always enough to derive what line numbers were added.
     git.fetch("origin", base_ref, "--depth=1000")
-    diff = git.diff("--unified=0", "FETCH_HEAD", "--", ".")
+    diff = git.diff("--unified=0", "FETCH_HEAD...HEAD")
     return parse_diff_output(diff)
 
 

tests/integration/conftest.py

@@ -0,0 +1,101 @@
+from __future__ import annotations
+
+import os
+import pathlib
+import subprocess
+import uuid
+
+import pytest
+
+
+@pytest.fixture
+def in_integration_env(integration_env, integration_dir):
+    curdir = os.getcwd()
+    os.chdir(integration_dir)
+    yield integration_dir
+    os.chdir(curdir)
+
+
+@pytest.fixture
+def integration_dir(tmp_path: pathlib.Path):
+    test_dir = tmp_path / "integration_test"
+    test_dir.mkdir()
+    return test_dir
+
+
+@pytest.fixture
+def file_path(integration_dir):
+    return integration_dir / "foo.py"
+
+
+@pytest.fixture
+def write_file(file_path):
+    def _(*variables):
+        content = "import os"
+        for i, var in enumerate(variables):
+            content += f"""\nif os.environ.get("{var}"):\n    {i}\n"""
+        file_path.write_text(content, encoding="utf8")
+
+    return _
+
+
+@pytest.fixture
+def run_coverage(file_path, integration_dir):
+    def _(*variables):
+        subprocess.check_call(
+            ["coverage", "run", "--parallel", file_path.name],
+            cwd=integration_dir,
+            env=os.environ | dict.fromkeys(variables, "1"),
+        )
+
+    return _
+
+
+@pytest.fixture
+def commit(integration_dir):
+    def _():
+        subprocess.check_call(
+            ["git", "add", "."],
+            cwd=integration_dir,
+        )
+        subprocess.check_call(
+            ["git", "commit", "-m", str(uuid.uuid4())],
+            cwd=integration_dir,
+            env={
+                "GIT_AUTHOR_NAME": "foo",
+                "GIT_AUTHOR_EMAIL": "foo",
+                "GIT_COMMITTER_NAME": "foo",
+                "GIT_COMMITTER_EMAIL": "foo",
+                "GIT_CONFIG_GLOBAL": "/dev/null",
+                "GIT_CONFIG_SYSTEM": "/dev/null",
+            },
+        )
+
+    return _
+
+
+@pytest.fixture
+def integration_env(integration_dir, write_file, run_coverage, commit, request):
+    subprocess.check_call(["git", "init", "-b", "main"], cwd=integration_dir)
+    # diff coverage reads the "origin/{...}" branch so we simulate an origin remote
+    subprocess.check_call(["git", "remote", "add", "origin", "."], cwd=integration_dir)
+    write_file("A", "B")
+    commit()
+
+    add_branch_mark = request.node.get_closest_marker("add_branches")
+    for additional_branch in add_branch_mark.args if add_branch_mark else []:
+        subprocess.check_call(
+            ["git", "switch", "-c", additional_branch],
+            cwd=integration_dir,
+        )
+
+    subprocess.check_call(
+        ["git", "switch", "-c", "branch"],
+        cwd=integration_dir,
+    )
+
+    write_file("A", "B", "C", "D")
+    commit()
+
+    run_coverage("A", "C")
+    subprocess.check_call(["git", "fetch", "origin"], cwd=integration_dir)

tests/integration/test_coverage.py

@@ -0,0 +1,30 @@
+from __future__ import annotations
+
+import subprocess
+
+from coverage_comment import coverage
+from coverage_comment import subprocess as subprocess_module
+
+
+def test_get_added_lines(
+    commit, file_path, integration_dir, in_integration_env, write_file
+):
+    """
+    Lines added in the base_ref should not appear as added in HEAD
+    """
+    git = subprocess_module.Git()
+    relative_file_path = file_path.relative_to(integration_dir)
+
+    assert coverage.get_added_lines(git, "main") == {
+        relative_file_path: list(range(7, 13))  # Line numbers start at 1
+    }
+
+    subprocess.check_call(["git", "switch", "main"], cwd=integration_dir)
+    write_file("E", "F")
+    commit()
+    subprocess.check_call(["git", "push", "origin", "main"], cwd=integration_dir)
+    subprocess.check_call(["git", "switch", "branch"], cwd=integration_dir)
+
+    assert coverage.get_added_lines(git, "main") == {
+        relative_file_path: list(range(7, 13))  # Line numbers start at 1
+    }

tests/integration/test_main.py

@@ -1,59 +1,12 @@
 from __future__ import annotations
 
 import json
-import os
 import pathlib
-import subprocess
-import uuid
 
 import pytest
 
 from coverage_comment import main
 
-
-@pytest.fixture
-def in_integration_env(integration_env, integration_dir):
-    curdir = os.getcwd()
-    os.chdir(integration_dir)
-    yield integration_dir
-    os.chdir(curdir)
-
-
-@pytest.fixture
-def integration_dir(tmp_path: pathlib.Path):
-    test_dir = tmp_path / "integration_test"
-    test_dir.mkdir()
-    return test_dir
-
-
-@pytest.fixture
-def file_path(integration_dir):
-    return integration_dir / "foo.py"
-
-
-@pytest.fixture
-def write_file(file_path):
-    def _(*variables):
-        content = "import os"
-        for i, var in enumerate(variables):
-            content += f"""\nif os.environ.get("{var}"):\n    {i}\n"""
-        file_path.write_text(content, encoding="utf8")
-
-    return _
-
-
-@pytest.fixture
-def run_coverage(file_path, integration_dir):
-    def _(*variables):
-        subprocess.check_call(
-            ["coverage", "run", "--parallel", file_path.name],
-            cwd=integration_dir,
-            env=os.environ | dict.fromkeys(variables, "1"),
-        )
-
-    return _
-
-
 DIFF_STDOUT = """diff --git a/foo.py b/foo.py
 index 6c08c94..b65c612 100644
 --- a/foo.py
@@ -68,56 +21,6 @@ def _(*variables):
 """
 
 
-@pytest.fixture
-def commit(integration_dir):
-    def _():
-        subprocess.check_call(
-            ["git", "add", "."],
-            cwd=integration_dir,
-        )
-        subprocess.check_call(
-            ["git", "commit", "-m", str(uuid.uuid4())],
-            cwd=integration_dir,
-            env={
-                "GIT_AUTHOR_NAME": "foo",
-                "GIT_AUTHOR_EMAIL": "foo",
-                "GIT_COMMITTER_NAME": "foo",
-                "GIT_COMMITTER_EMAIL": "foo",
-                "GIT_CONFIG_GLOBAL": "/dev/null",
-                "GIT_CONFIG_SYSTEM": "/dev/null",
-            },
-        )
-
-    return _
-
-
-@pytest.fixture
-def integration_env(integration_dir, write_file, run_coverage, commit, request):
-    subprocess.check_call(["git", "init", "-b", "main"], cwd=integration_dir)
-    # diff coverage reads the "origin/{...}" branch so we simulate an origin remote
-    subprocess.check_call(["git", "remote", "add", "origin", "."], cwd=integration_dir)
-    write_file("A", "B")
-    commit()
-
-    add_branch_mark = request.node.get_closest_marker("add_branches")
-    for additional_branch in add_branch_mark.args if add_branch_mark else []:
-        subprocess.check_call(
-            ["git", "switch", "-c", additional_branch],
-            cwd=integration_dir,
-        )
-
-    subprocess.check_call(
-        ["git", "switch", "-c", "branch"],
-        cwd=integration_dir,
-    )
-
-    write_file("A", "B", "C", "D")
-    commit()
-
-    run_coverage("A", "C")
-    subprocess.check_call(["git", "fetch", "origin"], cwd=integration_dir)
-
-
 def test_action__invalid_event_name(session, push_config, in_integration_env, get_logs):
     session.register("GET", "/repos/py-cov-action/foobar")(
         json={"default_branch": "main", "visibility": "public"}
@@ -172,7 +75,7 @@ def checker(payload):
     )(status_code=403)
 
     git.register("git fetch origin main --depth=1000")()
-    git.register("git diff --unified=0 FETCH_HEAD -- .")(stdout=DIFF_STDOUT)
+    git.register("git diff --unified=0 FETCH_HEAD...HEAD")(stdout=DIFF_STDOUT)
 
     result = main.action(
         config=pull_request_config(
@@ -253,7 +156,7 @@ def checker(payload):
     )(status_code=403)
 
     git.register("git fetch origin foo --depth=1000")(stdout=DIFF_STDOUT)
-    git.register("git diff --unified=0 FETCH_HEAD -- .")(stdout=DIFF_STDOUT)
+    git.register("git diff --unified=0 FETCH_HEAD...HEAD")(stdout=DIFF_STDOUT)
 
     result = main.action(
         config=pull_request_config(
@@ -300,7 +203,7 @@ def test_action__pull_request__post_comment(
     session.register("GET", "/repos/py-cov-action/foobar/issues/2/comments")(json=[])
 
     git.register("git fetch origin main --depth=1000")()
-    git.register("git diff --unified=0 FETCH_HEAD -- .")(stdout=DIFF_STDOUT)
+    git.register("git diff --unified=0 FETCH_HEAD...HEAD")(stdout=DIFF_STDOUT)
 
     comment = None
 
@@ -347,7 +250,7 @@ def test_action__push__non_default_branch(
         json={"default_branch": "main", "visibility": "public"}
     )
     git.register("git fetch origin main --depth=1000")(stdout=DIFF_STDOUT)
-    git.register("git diff --unified=0 FETCH_HEAD -- .")(stdout=DIFF_STDOUT)
+    git.register("git diff --unified=0 FETCH_HEAD...HEAD")(stdout=DIFF_STDOUT)
 
     payload = json.dumps({"coverage": 30.00})
     # There is an existing badge in this test, allowing to test the coverage evolution
@@ -436,7 +339,7 @@ def test_action__push__non_default_branch__no_pr(
         json={"default_branch": "main", "visibility": "public"}
     )
     git.register("git fetch origin main --depth=1000")(stdout=DIFF_STDOUT)
-    git.register("git diff --unified=0 FETCH_HEAD -- .")(stdout=DIFF_STDOUT)
+    git.register("git diff --unified=0 FETCH_HEAD...HEAD")(stdout=DIFF_STDOUT)
 
     payload = json.dumps({"coverage": 30.00})
     # There is an existing badge in this test, allowing to test the coverage evolution
@@ -500,7 +403,7 @@ def test_action__pull_request__force_store_comment(
     )(text=payload, headers={"content-type": "application/vnd.github.raw+json"})
 
     git.register("git fetch origin main --depth=1000")()
-    git.register("git diff --unified=0 FETCH_HEAD -- .")(stdout=DIFF_STDOUT)
+    git.register("git diff --unified=0 FETCH_HEAD...HEAD")(stdout=DIFF_STDOUT)
 
     result = main.action(
         config=pull_request_config(FORCE_WORKFLOW_RUN=True, GITHUB_OUTPUT=output_file),
@@ -531,7 +434,7 @@ def test_action__pull_request__post_comment__no_marker(
     )(status_code=404)
 
     git.register("git fetch origin main --depth=1000")()
-    git.register("git diff --unified=0 FETCH_HEAD -- .")(stdout=DIFF_STDOUT)
+    git.register("git diff --unified=0 FETCH_HEAD...HEAD")(stdout=DIFF_STDOUT)
 
     result = main.action(
         config=pull_request_config(COMMENT_TEMPLATE="""foo"""),
@@ -556,7 +459,7 @@ def test_action__pull_request__annotations(
     )(status_code=404)
 
     git.register("git fetch origin main --depth=1000")()
-    git.register("git diff --unified=0 FETCH_HEAD -- .")(stdout=DIFF_STDOUT)
+    git.register("git diff --unified=0 FETCH_HEAD...HEAD")(stdout=DIFF_STDOUT)
 
     # Who am I
     session.register("GET", "/user")(json={"login": "foo"})
@@ -598,7 +501,7 @@ def test_action__pull_request__post_comment__template_error(
     )(status_code=404)
 
     git.register("git fetch origin main --depth=1000")()
-    git.register("git diff --unified=0 FETCH_HEAD -- .")(stdout=DIFF_STDOUT)
+    git.register("git diff --unified=0 FETCH_HEAD...HEAD")(stdout=DIFF_STDOUT)
 
     result = main.action(
         config=pull_request_config(COMMENT_TEMPLATE="""{%"""),