efiop: The failing test might be related to https://github.com/iterative/dvc/pull/3991 CC @pmrowla 
diff --git a/dvc/repo/tree.py b/dvc/repo/tree.py
index 361e702ac..b1fb1192c 100644
--- a/dvc/repo/tree.py
+++ b/dvc/repo/tree.py
@@ -61,6 +61,10 @@ class DvcTree(BaseTree):
         except OutputNotFoundError as exc:
             raise FileNotFoundError from exc
 
+        # NOTE: this handles both dirty and checkout-ed out at the same time
+        if self.repo.tree.exists(path):
+            return self.repo.tree.open(path, mode=mode, encoding=encoding)
+
         if len(outs) != 1 or (
             outs[0].is_dir_checksum and path == outs[0].path_info
         ):
@@ -252,13 +256,9 @@ class RepoTree(BaseTree):
             encoding = None
 
         if self.dvctree and self.dvctree.exists(path):
-            try:
-                return self.dvctree.open(
-                    path, mode=mode, encoding=encoding, **kwargs
-                )
-            except FileNotFoundError:
-                if self.isdvc(path):
-                    raise
+            return self.dvctree.open(
+                path, mode=mode, encoding=encoding, **kwargs
+            )
         return self.repo.tree.open(path, mode=mode, encoding=encoding)
 
     def exists(self, path):

make sure metrics/plots can compare dirty repo with the last commit by default
>  Which versions get compared by default? without sending arguments
> I expected the present metrics file to be plotted on top of the last commit but if I manually change this metrics file, the changes are not reflected in the plot.
>  Only if I run dvc repro in a way that generates a different metrics file does it pick up the changes and plots them.
>  Where is this version coming from? I haven't committed anything to Git.
>  On DVC 1.0

https://discordapp.com/channels/485586884165107732/563406153334128681/719342575835676733
diff --git a/tests/func/metrics/test_diff.py b/tests/func/metrics/test_diff.py
index 121c5681a..ce62b7b57 100644
--- a/tests/func/metrics/test_diff.py
+++ b/tests/func/metrics/test_diff.py
@@ -153,3 +153,20 @@ def test_no_commits(tmp_dir):
     assert Git().no_commits
 
     assert Repo.init().metrics.diff() == {}
+
+
+def test_metrics_diff_dirty(tmp_dir, scm, dvc, run_copy_metrics):
+    def _gen(val):
+        tmp_dir.gen({"m_temp.yaml": str(val)})
+        run_copy_metrics("m_temp.yaml", "m.yaml", metrics=["m.yaml"])
+        dvc.scm.commit(str(val))
+
+    _gen(1)
+    _gen(2)
+    _gen(3)
+
+    tmp_dir.gen({"m.yaml": "4"})
+
+    expected = {"m.yaml": {"": {"old": 3, "new": 4, "diff": 1}}}
+
+    assert dvc.metrics.diff() == expected
diff --git a/tests/func/params/test_diff.py b/tests/func/params/test_diff.py
index f5ee537fb..7d7a99640 100644
--- a/tests/func/params/test_diff.py
+++ b/tests/func/params/test_diff.py
@@ -24,6 +24,20 @@ def test_diff(tmp_dir, scm, dvc):
     }
 
 
+def test_diff_dirty(tmp_dir, scm, dvc):
+    tmp_dir.gen("params.yaml", "foo: bar")
+    dvc.run(cmd="echo params.yaml", params=["foo"], single_stage=True)
+    scm.add(["params.yaml", "Dvcfile"])
+    scm.commit("bar")
+
+    tmp_dir.scm_gen("params.yaml", "foo: baz", commit="baz")
+    tmp_dir.gen("params.yaml", "foo: qux")
+
+    assert dvc.params.diff() == {
+        "params.yaml": {"foo": {"old": "baz", "new": "qux"}}
+    }
+
+
 def test_diff_new(tmp_dir, scm, dvc):
     tmp_dir.gen("params.yaml", "foo: bar")
     dvc.run(cmd="echo params.yaml", params=["foo"], single_stage=True)
diff --git a/tests/func/plots/test_diff.py b/tests/func/plots/test_diff.py
index a59802398..c04fc4206 100644
--- a/tests/func/plots/test_diff.py
+++ b/tests/func/plots/test_diff.py
@@ -39,3 +39,17 @@ def test_diff_dirty(tmp_dir, scm, dvc, run_copy_metrics):
     ]
     assert plot_content["encoding"]["x"]["field"] == PlotData.INDEX_FIELD
     assert plot_content["encoding"]["y"]["field"] == "y"
+
+    _write_json(tmp_dir, [{"y": 7}, {"y": 8}], "metric.json")
+
+    plot_string = dvc.plots.diff(props={"fields": {"y"}})["metric.json"]
+
+    plot_content = json.loads(plot_string)
+    assert plot_content["data"]["values"] == [
+        {"y": 3, PlotData.INDEX_FIELD: 0, "rev": "HEAD"},
+        {"y": 5, PlotData.INDEX_FIELD: 1, "rev": "HEAD"},
+        {"y": 7, PlotData.INDEX_FIELD: 0, "rev": "workspace"},
+        {"y": 8, PlotData.INDEX_FIELD: 1, "rev": "workspace"},
+    ]
+    assert plot_content["encoding"]["x"]["field"] == PlotData.INDEX_FIELD
+    assert plot_content["encoding"]["y"]["field"] == "y"
diff --git a/tests/func/test_api.py b/tests/func/test_api.py
index 825ffa57a..615882b98 100644
--- a/tests/func/test_api.py
+++ b/tests/func/test_api.py
@@ -114,6 +114,10 @@ def test_missing(remote_url, tmp_dir, dvc):
     # Remove cache to make foo missing
     remove(dvc.cache.local.cache_dir)
 
+    api.read("foo")
+
+    remove("foo")
+
     with pytest.raises(FileMissingError):
         api.read("foo")
 
diff --git a/tests/func/test_update.py b/tests/func/test_update.py
index 529176fb4..b5bc9d14e 100644
--- a/tests/func/test_update.py
+++ b/tests/func/test_update.py
@@ -52,9 +52,9 @@ def test_update_import_after_remote_updates_to_dvc(tmp_dir, dvc, erepo_dir):
     new_rev = None
     with erepo_dir.branch("branch", new=False), erepo_dir.chdir():
         erepo_dir.scm.repo.index.remove(["version"])
-        erepo_dir.dvc_gen("version", "updated")
-        erepo_dir.scm.add(["version", "version.dvc"])
-        erepo_dir.scm.commit("upgrade to DVC tracking")
+        erepo_dir.dvc_gen(
+            "version", "updated", commit="upgrade to DVC tracking"
+        )
         new_rev = erepo_dir.scm.get_rev()
 
     assert old_rev != new_rev
diff --git a/tests/unit/repo/test_repo_tree.py b/tests/unit/repo/test_repo_tree.py
index 879834b28..9b00d3641 100644
--- a/tests/unit/repo/test_repo_tree.py
+++ b/tests/unit/repo/test_repo_tree.py
@@ -26,6 +26,24 @@ def test_open(tmp_dir, dvc):
         assert fobj.read() == "foo"
 
 
+def test_open_dirty_hash(tmp_dir, dvc):
+    tmp_dir.dvc_gen("file", "file")
+    (tmp_dir / "file").write_text("something")
+
+    tree = RepoTree(dvc)
+    with tree.open("file", "r") as fobj:
+        assert fobj.read() == "something"
+
+
+def test_open_dirty_no_hash(tmp_dir, dvc):
+    tmp_dir.gen("file", "file")
+    (tmp_dir / "file.dvc").write_text("outs:\n- path: file\n")
+
+    tree = RepoTree(dvc)
+    with tree.open("file", "r") as fobj:
+        assert fobj.read() == "file"
+
+
 def test_open_in_history(tmp_dir, scm, dvc):
     tmp_dir.gen("foo", "foo")
     dvc.add("foo")
diff --git a/tests/unit/repo/test_tree.py b/tests/unit/repo/test_tree.py
index edcb3a0c1..50191224f 100644
--- a/tests/unit/repo/test_tree.py
+++ b/tests/unit/repo/test_tree.py
@@ -26,6 +26,24 @@ def test_open(tmp_dir, dvc):
         assert fobj.read() == "foo"
 
 
+def test_open_dirty_hash(tmp_dir, dvc):
+    tmp_dir.dvc_gen("file", "file")
+    (tmp_dir / "file").write_text("something")
+
+    tree = DvcTree(dvc)
+    with tree.open("file", "r") as fobj:
+        assert fobj.read() == "something"
+
+
+def test_open_dirty_no_hash(tmp_dir, dvc):
+    tmp_dir.gen("file", "file")
+    (tmp_dir / "file.dvc").write_text("outs:\n- path: file\n")
+
+    tree = DvcTree(dvc)
+    with tree.open("file", "r") as fobj:
+        assert fobj.read() == "file"
+
+
 def test_open_in_history(tmp_dir, scm, dvc):
     tmp_dir.gen("foo", "foo")
     dvc.add("foo")

pip install -e .[all]
parse_log_pytest
pytest
pytest pytest-cov pytest-xdist pytest-mock pytest-lazy-fixture flaky mock xmltodict awscli google-compute-engine Pygments collective.checkdocs flake8 psutil flake8-docstrings pydocstyle jaraco.windows mock-ssh-server moto rangehttpserver beautifulsoup4 flake8-bugbear flake8-comprehensions flake8-string-format pylint pylint-pytest pylint-plugin-utils wget filelock
apt-get update apt-get install -y gcc
3.7
pytest --no-header -rA --tb=line --color=no -p no:cacheprovider -W ignore::DeprecationWarning
aliyun-python-sdk-core==2.16.0
aliyun-python-sdk-core-v3==2.13.33
aliyun-python-sdk-kms==2.16.5
appdirs==1.4.4
astroid==2.15.8
atpublic==3.1.2
attrs @ file:///croot/attrs_1668696182826/work
autocommand==2.2.2
awscli==1.31.13
azure-common==1.1.28
azure-storage-blob==2.1.0
azure-storage-common==2.1.0
bcrypt==4.2.1
beautifulsoup4==4.13.3
boto==2.49.0
boto3==1.33.13
botocore==1.33.13
cachetools==4.2.4
certifi @ file:///croot/certifi_1671487769961/work/certifi
cffi==1.15.1
charset-normalizer==3.4.1
collective.checkdocs==0.2
colorama==0.4.4
configobj==5.0.9
coverage==7.2.7
crcmod==1.7
cryptography==44.0.2
decorator==5.1.1
dill==0.3.7
distro==1.9.0
docutils==0.16
dpath==2.2.0
-e git+https://github.com/iterative/dvc.git@4042d5232dc8aa5238f800e917e9b062719d8ec9#egg=dvc
execnet==2.0.2
filelock==3.12.2
flake8==5.0.4
flake8-bugbear==23.3.12
flake8-comprehensions==3.13.0
flake8-docstrings==1.7.0
flake8-string-format==0.3.0
flaky==3.8.1
flatten-json==0.1.14
flit_core @ file:///opt/conda/conda-bld/flit-core_1644941570762/work/source/flit_core
flufl.lock==7.1.1
funcy==2.0
future==1.0.0
gitdb==4.0.12
GitPython==3.1.44
google-api-core==2.10.2
google-api-python-client==2.166.0
google-auth==1.35.0
google-auth-httplib2==0.2.0
google-cloud-core==1.7.3
google-cloud-storage==1.19.0
google-compute-engine==2.8.13
google-crc32c==1.5.0
google-resumable-media==2.7.2
googleapis-common-protos==1.69.2
grandalf==0.6
httplib2==0.22.0
idna==3.10
importlib-metadata==4.2.0
importlib-resources==5.12.0
inflect==6.0.5
iniconfig @ file:///home/linux1/recipes/ci/iniconfig_1610983019677/work
isort==5.11.5
jaraco.classes==3.2.3
jaraco.collections==4.2.0
jaraco.context==4.3.0
jaraco.functools==3.7.0
jaraco.structures==2.1.0
jaraco.text==3.11.1
jaraco.ui==2.3.0
jaraco.windows==5.7.0
Jinja2==3.1.6
jmespath==0.10.0
jsonpath-ng==1.7.0
lazy-object-proxy==1.9.0
MarkupSafe==2.1.5
mccabe==0.7.0
mock==5.2.0
mock-ssh-server==0.9.1
more-itertools==9.1.0
moto==4.2.14
nanotime==0.5.2
networkx==2.3
numpy==1.21.6
oauth2client==4.1.3
oss2==2.6.1
packaging @ file:///croot/packaging_1671697413597/work
paramiko==3.5.1
path==16.6.0
pathspec==0.11.2
platformdirs==4.0.0
pluggy @ file:///tmp/build/80754af9/pluggy_1648042572264/work
ply==3.11
protobuf==4.24.4
psutil==7.0.0
py @ file:///opt/conda/conda-bld/py_1644396412707/work
pyarrow==12.0.1
pyasn1==0.5.1
pyasn1-modules==0.3.0
pycodestyle==2.9.1
pycparser==2.21
pycryptodome==3.22.0
pydantic==1.10.21
pydocstyle==6.3.0
pydot==2.0.0
PyDrive2==1.15.4
pyflakes==2.5.0
Pygments==2.17.2
pygtrie==2.3.2
pylint==2.17.7
pylint-plugin-utils==0.8.2
pylint-pytest==1.1.8
PyNaCl==1.5.0
pyOpenSSL==25.0.0
pyparsing==3.1.4
pytest==7.1.2
pytest-cov==4.1.0
pytest-lazy-fixture==0.6.3
pytest-mock==3.11.1
pytest-xdist==3.5.0
python-dateutil==2.9.0.post0
PyYAML==5.3.1
rangehttpserver==1.4.0
requests==2.31.0
responses==0.23.3
rsa==4.7.2
ruamel.yaml==0.18.10
ruamel.yaml.clib==0.2.8
s3transfer==0.8.2
shortuuid==1.0.13
six==1.17.0
smmap==5.0.2
snowballstemmer==2.2.0
soupsieve==2.4.1
tabulate==0.9.0
tomli @ file:///opt/conda/conda-bld/tomli_1657175507142/work
tomlkit==0.12.5
tqdm==4.67.1
typed-ast==1.5.5
types-PyYAML==6.0.12.12
typing_extensions==4.7.1
uritemplate==4.1.1
urllib3==1.26.20
voluptuous==0.14.1
Werkzeug==2.2.3
wget==3.2
wrapt==1.16.0
xmltodict==0.14.2
zc.lockfile==3.0.post1
zipp @ file:///croot/zipp_1672387121353/work

name: dvc
channels:
  - defaults
  - https://repo.anaconda.com/pkgs/main
  - https://repo.anaconda.com/pkgs/r
  - conda-forge
dependencies:
  - _libgcc_mutex=0.1=main
  - _openmp_mutex=5.1=1_gnu
  - attrs=22.1.0=py37h06a4308_0
  - ca-certificates=2025.2.25=h06a4308_0
  - certifi=2022.12.7=py37h06a4308_0
  - flit-core=3.6.0=pyhd3eb1b0_0
  - importlib_metadata=4.11.3=hd3eb1b0_0
  - iniconfig=1.1.1=pyhd3eb1b0_0
  - ld_impl_linux-64=2.40=h12ee557_0
  - libffi=3.4.4=h6a678d5_1
  - libgcc-ng=11.2.0=h1234567_1
  - libgomp=11.2.0=h1234567_1
  - libstdcxx-ng=11.2.0=h1234567_1
  - ncurses=6.4=h6a678d5_0
  - openssl=1.1.1w=h7f8727e_0
  - packaging=22.0=py37h06a4308_0
  - pip=22.3.1=py37h06a4308_0
  - pluggy=1.0.0=py37h06a4308_1
  - py=1.11.0=pyhd3eb1b0_0
  - pytest=7.1.2=py37h06a4308_0
  - python=3.7.16=h7a1cb2a_0
  - readline=8.2=h5eee18b_0
  - setuptools=65.6.3=py37h06a4308_0
  - sqlite=3.45.3=h5eee18b_0
  - tk=8.6.14=h39e8969_0
  - tomli=2.0.1=py37h06a4308_0
  - wheel=0.38.4=py37h06a4308_0
  - xz=5.6.4=h5eee18b_1
  - zipp=3.11.0=py37h06a4308_0
  - zlib=1.2.13=h5eee18b_1
  - pip:
      - aliyun-python-sdk-core==2.16.0
      - aliyun-python-sdk-core-v3==2.13.33
      - aliyun-python-sdk-kms==2.16.5
      - appdirs==1.4.4
      - astroid==2.15.8
      - atpublic==3.1.2
      - autocommand==2.2.2
      - awscli==1.31.13
      - azure-common==1.1.28
      - azure-storage-blob==2.1.0
      - azure-storage-common==2.1.0
      - bcrypt==4.2.1
      - beautifulsoup4==4.13.3
      - boto==2.49.0
      - boto3==1.33.13
      - botocore==1.33.13
      - cachetools==4.2.4
      - cffi==1.15.1
      - charset-normalizer==3.4.1
      - collective-checkdocs==0.2
      - colorama==0.4.4
      - configobj==5.0.9
      - coverage==7.2.7
      - crcmod==1.7
      - cryptography==44.0.2
      - decorator==5.1.1
      - dill==0.3.7
      - distro==1.9.0
      - docutils==0.16
      - dpath==2.2.0
      - dvc==1.0.0a10+4042d5
      - execnet==2.0.2
      - filelock==3.12.2
      - flake8==5.0.4
      - flake8-bugbear==23.3.12
      - flake8-comprehensions==3.13.0
      - flake8-docstrings==1.7.0
      - flake8-string-format==0.3.0
      - flaky==3.8.1
      - flatten-json==0.1.14
      - flufl-lock==7.1.1
      - funcy==2.0
      - future==1.0.0
      - gitdb==4.0.12
      - gitpython==3.1.44
      - google-api-core==2.10.2
      - google-api-python-client==2.166.0
      - google-auth==1.35.0
      - google-auth-httplib2==0.2.0
      - google-cloud-core==1.7.3
      - google-cloud-storage==1.19.0
      - google-compute-engine==2.8.13
      - google-crc32c==1.5.0
      - google-resumable-media==2.7.2
      - googleapis-common-protos==1.69.2
      - grandalf==0.6
      - httplib2==0.22.0
      - idna==3.10
      - importlib-metadata==4.2.0
      - importlib-resources==5.12.0
      - inflect==6.0.5
      - isort==5.11.5
      - jaraco-classes==3.2.3
      - jaraco-collections==4.2.0
      - jaraco-context==4.3.0
      - jaraco-functools==3.7.0
      - jaraco-structures==2.1.0
      - jaraco-text==3.11.1
      - jaraco-ui==2.3.0
      - jaraco-windows==5.7.0
      - jinja2==3.1.6
      - jmespath==0.10.0
      - jsonpath-ng==1.7.0
      - lazy-object-proxy==1.9.0
      - markupsafe==2.1.5
      - mccabe==0.7.0
      - mock==5.2.0
      - mock-ssh-server==0.9.1
      - more-itertools==9.1.0
      - moto==4.2.14
      - nanotime==0.5.2
      - networkx==2.3
      - numpy==1.21.6
      - oauth2client==4.1.3
      - oss2==2.6.1
      - paramiko==3.5.1
      - path==16.6.0
      - pathspec==0.11.2
      - platformdirs==4.0.0
      - ply==3.11
      - protobuf==4.24.4
      - psutil==7.0.0
      - pyarrow==12.0.1
      - pyasn1==0.5.1
      - pyasn1-modules==0.3.0
      - pycodestyle==2.9.1
      - pycparser==2.21
      - pycryptodome==3.22.0
      - pydantic==1.10.21
      - pydocstyle==6.3.0
      - pydot==2.0.0
      - pydrive2==1.15.4
      - pyflakes==2.5.0
      - pygments==2.17.2
      - pygtrie==2.3.2
      - pylint==2.17.7
      - pylint-plugin-utils==0.8.2
      - pylint-pytest==1.1.8
      - pynacl==1.5.0
      - pyopenssl==25.0.0
      - pyparsing==3.1.4
      - pytest-cov==4.1.0
      - pytest-lazy-fixture==0.6.3
      - pytest-mock==3.11.1
      - pytest-xdist==3.5.0
      - python-dateutil==2.9.0.post0
      - pyyaml==5.3.1
      - rangehttpserver==1.4.0
      - requests==2.31.0
      - responses==0.23.3
      - rsa==4.7.2
      - ruamel-yaml==0.18.10
      - ruamel-yaml-clib==0.2.8
      - s3transfer==0.8.2
      - shortuuid==1.0.13
      - six==1.17.0
      - smmap==5.0.2
      - snowballstemmer==2.2.0
      - soupsieve==2.4.1
      - tabulate==0.9.0
      - tomlkit==0.12.5
      - tqdm==4.67.1
      - typed-ast==1.5.5
      - types-pyyaml==6.0.12.12
      - typing-extensions==4.7.1
      - uritemplate==4.1.1
      - urllib3==1.26.20
      - voluptuous==0.14.1
      - werkzeug==2.2.3
      - wget==3.2
      - wrapt==1.16.0
      - xmltodict==0.14.2
      - zc-lockfile==3.0.post1
prefix: /opt/conda/envs/dvc

tests/func/metrics/test_diff.py::test_metrics_diff_dirty tests/func/test_api.py::test_missing[Local] tests/unit/repo/test_repo_tree.py::test_open_dirty_hash tests/unit/repo/test_repo_tree.py::test_open_dirty_no_hash tests/unit/repo/test_tree.py::test_open_dirty_hash tests/unit/repo/test_tree.py::test_open_dirty_no_hash
tests/func/metrics/test_diff.py::test_metrics_diff_simple tests/func/metrics/test_diff.py::test_metrics_diff_yaml tests/func/metrics/test_diff.py::test_metrics_diff_json tests/func/metrics/test_diff.py::test_metrics_diff_json_unchanged tests/func/metrics/test_diff.py::test_metrics_diff_broken_json tests/func/metrics/test_diff.py::test_metrics_diff_no_metrics tests/func/metrics/test_diff.py::test_metrics_diff_new_metric tests/func/metrics/test_diff.py::test_metrics_diff_deleted_metric tests/func/metrics/test_diff.py::test_metrics_diff_with_unchanged tests/func/metrics/test_diff.py::test_no_commits tests/func/params/test_diff.py::test_diff_no_params tests/func/params/test_diff.py::test_diff_no_changes tests/func/params/test_diff.py::test_diff tests/func/params/test_diff.py::test_diff_dirty tests/func/params/test_diff.py::test_diff_new tests/func/params/test_diff.py::test_diff_deleted tests/func/params/test_diff.py::test_diff_deleted_config tests/func/params/test_diff.py::test_diff_list tests/func/params/test_diff.py::test_diff_dict tests/func/params/test_diff.py::test_diff_with_unchanged tests/func/params/test_diff.py::test_pipeline_tracked_params tests/func/params/test_diff.py::test_no_commits tests/func/plots/test_diff.py::test_diff_dirty tests/func/test_api.py::test_get_url_requires_dvc tests/func/test_api.py::test_open[Local] tests/func/test_api.py::test_open_external[Local] tests/func/test_api.py::test_open_granular[Local] tests/func/test_api.py::test_open_scm_controlled tests/func/test_api.py::test_open_not_cached tests/func/test_update.py::test_update_import[True] tests/func/test_update.py::test_update_import[False] tests/func/test_update.py::test_update_import_after_remote_updates_to_dvc tests/func/test_update.py::test_update_before_and_after_dvc_init tests/func/test_update.py::test_update_import_url tests/func/test_update.py::test_update_rev tests/func/test_update.py::test_update_recursive tests/unit/repo/test_repo_tree.py::test_exists tests/unit/repo/test_repo_tree.py::test_open tests/unit/repo/test_repo_tree.py::test_open_in_history tests/unit/repo/test_repo_tree.py::test_isdir_isfile tests/unit/repo/test_repo_tree.py::test_isdir_mixed tests/unit/repo/test_repo_tree.py::test_walk[False-extra_expected0] tests/unit/repo/test_repo_tree.py::test_walk[True-extra_expected1] tests/unit/repo/test_repo_tree.py::test_isdvc tests/unit/repo/test_tree.py::test_exists tests/unit/repo/test_tree.py::test_open tests/unit/repo/test_tree.py::test_open_in_history tests/unit/repo/test_tree.py::test_isdir_isfile tests/unit/repo/test_tree.py::test_isdir_mixed tests/unit/repo/test_tree.py::test_walk tests/unit/repo/test_tree.py::test_walk_dir[False-expected0] tests/unit/repo/test_tree.py::test_walk_dir[True-expected1] tests/unit/repo/test_tree.py::test_isdvc
dvc/repo/tree.py
dvc/repo/tree.py