Merge 82aab8e265 into c3f13d2505

crates/uv/src/commands/project/add.rs

@@ -239,7 +239,7 @@ pub(crate) async fn add(
                 .with_context(|| format!("Package `{package}` not found in workspace"))?,
             )
         } else {
-            VirtualProject::discover(
+            VirtualProject::discover_defaulted(
                 project_dir,
                 &DiscoveryOptions::default(),
                 &WorkspaceCache::default(),

crates/uv/src/commands/project/export.rs

@@ -87,7 +87,7 @@ pub(crate) async fn export(
         ExportTarget::Script(script)
     } else {
         let project = if frozen {
-            VirtualProject::discover(
+            VirtualProject::discover_defaulted(
                 project_dir,
                 &DiscoveryOptions {
                     members: MemberDiscovery::None,
@@ -104,8 +104,12 @@ pub(crate) async fn export(
                     .with_context(|| format!("Package `{package}` not found in workspace"))?,
             )
         } else {
-            VirtualProject::discover(project_dir, &DiscoveryOptions::default(), &workspace_cache)
-                .await?
+            VirtualProject::discover_defaulted(
+                project_dir,
+                &DiscoveryOptions::default(),
+                &workspace_cache,
+            )
+            .await?
         };
         ExportTarget::Project(project)
     };

crates/uv/src/commands/project/remove.rs

@@ -100,7 +100,7 @@ pub(crate) async fn remove(
                 .with_context(|| format!("Package `{package}` not found in workspace"))?,
             )
         } else {
-            VirtualProject::discover(
+            VirtualProject::discover_defaulted(
                 project_dir,
                 &DiscoveryOptions::default(),
                 &WorkspaceCache::default(),

crates/uv/src/commands/project/run.rs

@@ -526,7 +526,7 @@ hint: If you are running a script with `{}` in the shebang, you may need to incl
                     .with_context(|| format!("Package `{package}` not found in workspace"))?,
             ))
         } else {
-            match VirtualProject::discover(
+            match VirtualProject::discover_defaulted(
                 project_dir,
                 &DiscoveryOptions::default(),
                 &workspace_cache,

crates/uv/src/commands/project/sync.rs

@@ -83,7 +83,7 @@ pub(crate) async fn sync(
     } else {
         // Identify the project.
         let project = if frozen {
-            VirtualProject::discover(
+            VirtualProject::discover_defaulted(
                 project_dir,
                 &DiscoveryOptions {
                     members: MemberDiscovery::None,
@@ -100,8 +100,12 @@ pub(crate) async fn sync(
                     .with_context(|| format!("Package `{package}` not found in workspace"))?,
             )
         } else {
-            VirtualProject::discover(project_dir, &DiscoveryOptions::default(), &workspace_cache)
-                .await?
+            VirtualProject::discover_defaulted(
+                project_dir,
+                &DiscoveryOptions::default(),
+                &workspace_cache,
+            )
+            .await?
         };
 
         // TODO(lucab): improve warning content

crates/uv/src/commands/project/version.rs

@@ -231,7 +231,7 @@ async fn find_target(project_dir: &Path, package: Option<&PackageName>) -> Resul
             .with_context(|| format!("Package `{package}` not found in workspace"))?,
         )
     } else {
-        VirtualProject::discover(
+        VirtualProject::discover_defaulted(
             project_dir,
             &DiscoveryOptions::default(),
             &WorkspaceCache::default(),

crates/uv/src/commands/python/find.rs

@@ -44,8 +44,12 @@ pub(crate) async fn find(
     let project = if no_project {
         None
     } else {
-        match VirtualProject::discover(project_dir, &DiscoveryOptions::default(), &workspace_cache)
-            .await
+        match VirtualProject::discover_defaulted(
+            project_dir,
+            &DiscoveryOptions::default(),
+            &workspace_cache,
+        )
+        .await
         {
             Ok(project) => Some(project),
             Err(WorkspaceError::MissingProject(_)) => None,

crates/uv/src/commands/python/pin.rs

@@ -46,8 +46,12 @@ pub(crate) async fn pin(
     let virtual_project = if no_project {
         None
     } else {
-        match VirtualProject::discover(project_dir, &DiscoveryOptions::default(), &workspace_cache)
-            .await
+        match VirtualProject::discover_defaulted(
+            project_dir,
+            &DiscoveryOptions::default(),
+            &workspace_cache,
+        )
+        .await
         {
             Ok(virtual_project) => Some(virtual_project),
             Err(err) => {

crates/uv/src/commands/venv.rs

@@ -157,8 +157,12 @@ async fn venv_impl(
     let project = if no_project {
         None
     } else {
-        match VirtualProject::discover(project_dir, &DiscoveryOptions::default(), &workspace_cache)
-            .await
+        match VirtualProject::discover_defaulted(
+            project_dir,
+            &DiscoveryOptions::default(),
+            &workspace_cache,
+        )
+        .await
         {
             Ok(project) => Some(project),
             Err(WorkspaceError::MissingProject(_)) => None,

crates/uv/tests/it/edit.rs

@@ -4525,6 +4525,306 @@ fn add_non_project() -> Result<()> {
     Ok(())
 }
 
+#[test]
+fn add_virtual_empty() -> Result<()> {
+    // testing how `uv add` reacts to a pyproject with no `[project]` and nothing useful to it
+    let context = TestContext::new("3.12");
+
+    let pyproject_toml = context.temp_dir.child("pyproject.toml");
+    pyproject_toml.write_str(indoc! {r#"
+        [tool.mycooltool]
+        wow = "someconfig"
+    "#})?;
+
+    // Add normal dep (doesn't make sense)
+    uv_snapshot!(context.filters(), context.add()
+        .arg("sortedcontainers"), @r"
+    success: false
+    exit_code: 2
+    ----- stdout -----
+
+    ----- stderr -----
+    error: Project is missing a `[project]` table; add a `[project]` table to use production dependencies, or run `uv add --dev` instead
+    ");
+
+    let pyproject_toml = context.read("pyproject.toml");
+
+    insta::with_settings!({
+        filters => context.filters(),
+    }, {
+        assert_snapshot!(
+            pyproject_toml, @r#"
+        [tool.mycooltool]
+        wow = "someconfig"
+        "#
+        );
+    });
+
+    // Add dependency-group (can make sense!)
+    uv_snapshot!(context.filters(), context.add()
+        .arg("sortedcontainers")
+        .arg("--group").arg("dev"), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    warning: No `requires-python` value found in the workspace. Defaulting to `>=3.12`.
+    Resolved 1 package in [TIME]
+    Prepared 1 package in [TIME]
+    Installed 1 package in [TIME]
+     + sortedcontainers==2.4.0
+    ");
+
+    let pyproject_toml = context.read("pyproject.toml");
+
+    insta::with_settings!({
+        filters => context.filters(),
+    }, {
+        assert_snapshot!(
+            pyproject_toml, @r#"
+        [tool.mycooltool]
+        wow = "someconfig"
+
+        [dependency-groups]
+        dev = [
+            "sortedcontainers>=2.4.0",
+        ]
+        "#
+        );
+    });
+
+    Ok(())
+}
+
+#[test]
+fn add_virtual_dependency_group() -> Result<()> {
+    // testing basic `uv add --group` functionality
+    // when the pyproject.toml is fully virtual (no `[project]`)
+    let context = TestContext::new("3.12");
+
+    let pyproject_toml = context.temp_dir.child("pyproject.toml");
+    pyproject_toml.write_str(indoc! {r#"
+        [dependency-groups]
+        foo = ["sortedcontainers"]
+        bar = ["iniconfig"]
+        dev = ["sniffio"]
+    "#})?;
+
+    // Add to existing group
+    uv_snapshot!(context.filters(), context.add()
+        .arg("sortedcontainers")
+        .arg("--group").arg("dev"), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    warning: No `requires-python` value found in the workspace. Defaulting to `>=3.12`.
+    Resolved 3 packages in [TIME]
+    Prepared 2 packages in [TIME]
+    Installed 2 packages in [TIME]
+     + sniffio==1.3.1
+     + sortedcontainers==2.4.0
+    ");
+
+    let pyproject_toml = context.read("pyproject.toml");
+
+    insta::with_settings!({
+        filters => context.filters(),
+    }, {
+        assert_snapshot!(
+            pyproject_toml, @r#"
+        [dependency-groups]
+        foo = ["sortedcontainers"]
+        bar = ["iniconfig"]
+        dev = [
+            "sniffio",
+            "sortedcontainers>=2.4.0",
+        ]
+        "#
+        );
+    });
+
+    // Add to new group
+    uv_snapshot!(context.filters(), context.add()
+        .arg("sortedcontainers")
+        .arg("--group").arg("baz"), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    warning: No `requires-python` value found in the workspace. Defaulting to `>=3.12`.
+    Resolved 3 packages in [TIME]
+    Audited 2 packages in [TIME]
+    ");
+
+    let pyproject_toml = context.read("pyproject.toml");
+
+    insta::with_settings!({
+        filters => context.filters(),
+    }, {
+        assert_snapshot!(
+            pyproject_toml, @r#"
+        [dependency-groups]
+        foo = ["sortedcontainers"]
+        bar = ["iniconfig"]
+        dev = [
+            "sniffio",
+            "sortedcontainers>=2.4.0",
+        ]
+        baz = [
+            "sortedcontainers>=2.4.0",
+        ]
+        "#
+        );
+    });
+
+    Ok(())
+}
+
+#[test]
+fn remove_virtual_empty() -> Result<()> {
+    // testing how `uv remove` reacts to a pyproject with no `[project]` and nothing useful to it
+    let context = TestContext::new("3.12");
+
+    let pyproject_toml = context.temp_dir.child("pyproject.toml");
+    pyproject_toml.write_str(
+        r#"
+        [tool.mycooltool]
+        wow = "someconfig"
+
+        "#,
+    )?;
+
+    // Remove normal dep (doesn't make sense)
+    uv_snapshot!(context.filters(), context.remove()
+        .arg("sortedcontainers"), @r"
+    success: false
+    exit_code: 2
+    ----- stdout -----
+
+    ----- stderr -----
+    error: The dependency `sortedcontainers` could not be found in `project.dependencies`
+    ");
+
+    let pyproject_toml = context.read("pyproject.toml");
+
+    insta::with_settings!({
+        filters => context.filters(),
+    }, {
+        assert_snapshot!(
+            pyproject_toml, @r#"
+        [tool.mycooltool]
+        wow = "someconfig"
+        "#
+        );
+    });
+
+    // Remove dependency-group (can make sense, but nothing there!)
+    uv_snapshot!(context.filters(), context.remove()
+        .arg("sortedcontainers")
+        .arg("--group").arg("dev"), @r"
+    success: false
+    exit_code: 2
+    ----- stdout -----
+
+    ----- stderr -----
+    error: The dependency `sortedcontainers` could not be found in `tool.uv.dev-dependencies` or `tool.uv.dependency-groups.dev`
+    ");
+
+    let pyproject_toml = context.read("pyproject.toml");
+
+    insta::with_settings!({
+        filters => context.filters(),
+    }, {
+        assert_snapshot!(
+            pyproject_toml, @r#"
+        [tool.mycooltool]
+        wow = "someconfig"
+        "#
+        );
+    });
+
+    Ok(())
+}
+
+#[test]
+fn remove_virtual_dependency_group() -> Result<()> {
+    // testing basic `uv remove --group` functionality
+    // when the pyproject.toml is fully virtual (no `[project]`)
+    let context = TestContext::new("3.12");
+
+    let pyproject_toml = context.temp_dir.child("pyproject.toml");
+    pyproject_toml.write_str(indoc! {r#"
+        [dependency-groups]
+        foo = ["sortedcontainers"]
+        bar = ["iniconfig"]
+        dev = ["sniffio"]
+    "#})?;
+
+    // Remove from group
+    uv_snapshot!(context.filters(), context.remove()
+        .arg("sortedcontainers")
+        .arg("--group").arg("foo"), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    warning: No `requires-python` value found in the workspace. Defaulting to `>=3.12`.
+    Resolved 2 packages in [TIME]
+    Prepared 1 package in [TIME]
+    Installed 1 package in [TIME]
+     + sniffio==1.3.1
+    ");
+
+    let pyproject_toml = context.read("pyproject.toml");
+
+    insta::with_settings!({
+        filters => context.filters(),
+    }, {
+        assert_snapshot!(
+            pyproject_toml, @r#"
+        [dependency-groups]
+        foo = []
+        bar = ["iniconfig"]
+        dev = ["sniffio"]
+        "#
+        );
+    });
+
+    // Remove from non-existent group
+    uv_snapshot!(context.filters(), context.remove()
+        .arg("sortedcontainers")
+        .arg("--group").arg("baz"), @r"
+    success: false
+    exit_code: 2
+    ----- stdout -----
+
+    ----- stderr -----
+    error: The dependency `sortedcontainers` could not be found in `dependency-groups.baz`
+    ");
+
+    let pyproject_toml = context.read("pyproject.toml");
+
+    insta::with_settings!({
+        filters => context.filters(),
+    }, {
+        assert_snapshot!(
+            pyproject_toml, @r#"
+        [dependency-groups]
+        foo = []
+        bar = ["iniconfig"]
+        dev = ["sniffio"]
+        "#
+        );
+    });
+
+    Ok(())
+}
+
 /// Add the same requirement multiple times.
 #[test]
 fn add_repeat() -> Result<()> {

crates/uv/tests/it/export.rs

@@ -1143,6 +1143,102 @@ fn requirements_txt_non_project() -> Result<()> {
     Ok(())
 }
 
+#[test]
+fn virtual_empty() -> Result<()> {
+    // testing how `uv export` reacts to a pyproject with no `[project]` and nothing useful to it
+    let context = TestContext::new("3.12");
+
+    let pyproject_toml = context.temp_dir.child("pyproject.toml");
+    pyproject_toml.write_str(indoc! {r#"
+        [tool.mycooltool]
+        wow = "someconfig"
+    "#})?;
+
+    uv_snapshot!(context.filters(), context.export(), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+    # This file was autogenerated by uv via the following command:
+    #    uv export --cache-dir [CACHE_DIR]
+
+    ----- stderr -----
+    warning: No `requires-python` value found in the workspace. Defaulting to `>=3.12`.
+    Resolved in [TIME]
+    ");
+
+    Ok(())
+}
+
+#[test]
+fn virtual_dependency_group() -> Result<()> {
+    // testing basic `uv export --group` functionality
+    // when the pyproject.toml is fully virtual (no `[project]`)
+    let context = TestContext::new("3.12");
+
+    let pyproject_toml = context.temp_dir.child("pyproject.toml");
+    pyproject_toml.write_str(indoc! {r#"
+        [dependency-groups]
+        foo = ["sortedcontainers"]
+        bar = ["iniconfig"]
+        dev = ["sniffio"]
+    "#})?;
+
+    // default groups
+    uv_snapshot!(context.filters(), context.export(), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+    # This file was autogenerated by uv via the following command:
+    #    uv export --cache-dir [CACHE_DIR]
+    sniffio==1.3.1 \
+        --hash=sha256:2f6da418d1f1e0fddd844478f41680e794e6051915791a034ff65e5f100525a2 \
+        --hash=sha256:f4324edc670a0f49750a81b895f35c3adb843cca46f0530f79fc1babb23789dc
+
+    ----- stderr -----
+    warning: No `requires-python` value found in the workspace. Defaulting to `>=3.12`.
+    Resolved 3 packages in [TIME]
+    ");
+
+    // explicit --group
+    uv_snapshot!(context.filters(), context.export()
+        .arg("--group").arg("bar"), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+    # This file was autogenerated by uv via the following command:
+    #    uv export --cache-dir [CACHE_DIR] --group bar
+    iniconfig==2.0.0 \
+        --hash=sha256:2d91e135bf72d31a410b17c16da610a82cb55f6b0477d1a902134b24a455b8b3 \
+        --hash=sha256:b6a85871a79d2e3b22d2d1b94ac2824226a63c6b741c88f7ae975f18b6778374
+    sniffio==1.3.1 \
+        --hash=sha256:2f6da418d1f1e0fddd844478f41680e794e6051915791a034ff65e5f100525a2 \
+        --hash=sha256:f4324edc670a0f49750a81b895f35c3adb843cca46f0530f79fc1babb23789dc
+
+    ----- stderr -----
+    warning: No `requires-python` value found in the workspace. Defaulting to `>=3.12`.
+    Resolved 3 packages in [TIME]
+    ");
+
+    // explicit --only-group
+    uv_snapshot!(context.filters(), context.export()
+        .arg("--only-group").arg("foo"), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+    # This file was autogenerated by uv via the following command:
+    #    uv export --cache-dir [CACHE_DIR] --only-group foo
+    sortedcontainers==2.4.0 \
+        --hash=sha256:25caa5a06cc30b6b83d11423433f65d1f9d76c4c6a0c90e3379eaa43b9bfdb88 \
+        --hash=sha256:a163dcaede0f1c021485e957a39245190e74249897e2ae4b2aa38595db237ee0
+
+    ----- stderr -----
+    warning: No `requires-python` value found in the workspace. Defaulting to `>=3.12`.
+    Resolved 3 packages in [TIME]
+    ");
+
+    Ok(())
+}
+
 #[cfg(feature = "git")]
 #[test]
 fn requirements_txt_https_git_credentials() -> Result<()> {

crates/uv/tests/it/python_find.rs

@@ -403,6 +403,180 @@ fn python_find_project() {
     "###);
 }
 
+#[test]
+fn virtual_empty() {
+    // testing how `uv python find` reacts to a pyproject with no `[project]` and nothing useful to it
+    let context = TestContext::new_with_versions(&["3.10", "3.11", "3.12"]);
+
+    let pyproject_toml = context.temp_dir.child("pyproject.toml");
+    pyproject_toml
+        .write_str(indoc! {r#"
+        [tool.mycooltool]
+        wow = "someconfig"
+    "#})
+        .unwrap();
+
+    // Ask for the python
+    uv_snapshot!(context.filters(), context.python_find(), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+    [PYTHON-3.10]
+
+    ----- stderr -----
+    ");
+
+    // Ask for the python (--no-project)
+    uv_snapshot!(context.filters(), context.python_find()
+        .arg("--no-project"), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+    [PYTHON-3.10]
+
+    ----- stderr -----
+    ");
+
+    // Ask for specific python (3.11)
+    uv_snapshot!(context.filters(), context.python_find().arg("3.11"), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+    [PYTHON-3.11]
+
+    ----- stderr -----
+    ");
+
+    // Create a pin
+    uv_snapshot!(context.filters(), context.python_pin().arg("3.12"), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+    Pinned `.python-version` to `3.12`
+
+    ----- stderr -----
+    "###);
+
+    // Ask for the python
+    uv_snapshot!(context.filters(), context.python_find(), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+    [PYTHON-3.12]
+
+    ----- stderr -----
+    "###);
+
+    // Ask for specific python (3.11)
+    uv_snapshot!(context.filters(), context.python_find().arg("3.11"), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+    [PYTHON-3.11]
+
+    ----- stderr -----
+    ");
+
+    // Ask for the python (--no-project)
+    uv_snapshot!(context.filters(), context.python_find(), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+    [PYTHON-3.12]
+
+    ----- stderr -----
+    "###);
+}
+
+#[test]
+fn virtual_dependency_group() {
+    // testing basic `uv python find` functionality
+    // when the pyproject.toml is fully virtual (no `[project]`, but `[dependency-groups]` defined,
+    // which really shouldn't matter)
+    let context = TestContext::new_with_versions(&["3.10", "3.11", "3.12"]);
+
+    let pyproject_toml = context.temp_dir.child("pyproject.toml");
+    pyproject_toml
+        .write_str(indoc! {r#"
+        [dependency-groups]
+        foo = ["sortedcontainers"]
+        bar = ["iniconfig"]
+        dev = ["sniffio"]
+    "#})
+        .unwrap();
+
+    // Ask for the python
+    uv_snapshot!(context.filters(), context.python_find(), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+    [PYTHON-3.10]
+
+    ----- stderr -----
+    ");
+
+    // Ask for the python (--no-project)
+    uv_snapshot!(context.filters(), context.python_find()
+        .arg("--no-project"), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+    [PYTHON-3.10]
+
+    ----- stderr -----
+    ");
+
+    // Ask for specific python (3.11)
+    uv_snapshot!(context.filters(), context.python_find().arg("3.11"), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+    [PYTHON-3.11]
+
+    ----- stderr -----
+    ");
+
+    // Create a pin
+    uv_snapshot!(context.filters(), context.python_pin().arg("3.12"), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+    Pinned `.python-version` to `3.12`
+
+    ----- stderr -----
+    "###);
+
+    // Ask for the python
+    uv_snapshot!(context.filters(), context.python_find(), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+    [PYTHON-3.12]
+
+    ----- stderr -----
+    "###);
+
+    // Ask for specific python (3.11)
+    uv_snapshot!(context.filters(), context.python_find().arg("3.11"), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+    [PYTHON-3.11]
+
+    ----- stderr -----
+    ");
+
+    // Ask for the python (--no-project)
+    uv_snapshot!(context.filters(), context.python_find(), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+    [PYTHON-3.12]
+
+    ----- stderr -----
+    "###);
+}
+
 #[test]
 fn python_find_venv() {
     let context: TestContext = TestContext::new_with_versions(&["3.11", "3.12"])

crates/uv/tests/it/run.rs

@@ -3063,9 +3063,9 @@ fn run_module_stdin() {
     "###);
 }
 
-/// When the `pyproject.toml` file is invalid.
+/// Test for how run reacts to a pyproject.toml without a `[project]`
 #[test]
-fn run_project_toml_error() -> Result<()> {
+fn virtual_empty() -> Result<()> {
     let context = TestContext::new("3.12")
         .with_filtered_python_names()
         .with_filtered_virtualenv_bin()
@@ -3081,17 +3081,20 @@ fn run_project_toml_error() -> Result<()> {
     let init = src.child("__init__.py");
     init.touch()?;
 
-    // `run` should fail
-    uv_snapshot!(context.filters(), context.run().arg("python").arg("-c").arg("import sys; print(sys.executable)"), @r###"
-    success: false
-    exit_code: 2
+    // `run` should work fine
+    uv_snapshot!(context.filters(), context.run().arg("python").arg("-c").arg("import sys; print(sys.executable)"), @r"
+    success: true
+    exit_code: 0
     ----- stdout -----
+    [VENV]/[BIN]/python
 
     ----- stderr -----
-    error: No `project` table found in: `[TEMP_DIR]/pyproject.toml`
-    "###);
+    warning: No `requires-python` value found in the workspace. Defaulting to `>=3.12`.
+    Resolved in [TIME]
+    Audited in [TIME]
+    ");
 
-    // `run --no-project` should not
+    // `run --no-project` should also work fine
     uv_snapshot!(context.filters(), context.run().arg("--no-project").arg("python").arg("-c").arg("import sys; print(sys.executable)"), @r###"
     success: true
     exit_code: 0

crates/uv/tests/it/sync.rs

@@ -3875,6 +3875,95 @@ fn virtual_no_build() -> Result<()> {
     Ok(())
 }
 
+#[test]
+fn virtual_empty() -> Result<()> {
+    // testing how `uv sync` reacts to a pyproject with no `[project]` and nothing useful to it
+    let context = TestContext::new("3.12");
+
+    let pyproject_toml = context.temp_dir.child("pyproject.toml");
+    pyproject_toml.write_str(indoc! {r#"
+        [tool.mycooltool]
+        wow = "someconfig"
+    "#})?;
+
+    uv_snapshot!(context.filters(), context.sync(), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    warning: No `requires-python` value found in the workspace. Defaulting to `>=3.12`.
+    Resolved in [TIME]
+    Audited in [TIME]
+    ");
+
+    Ok(())
+}
+
+#[test]
+fn virtual_dependency_group() -> Result<()> {
+    // testing basic `uv sync --group` functionality
+    // when the pyproject.toml is fully virtual (no `[project]`)
+    let context = TestContext::new("3.12");
+
+    let pyproject_toml = context.temp_dir.child("pyproject.toml");
+    pyproject_toml.write_str(indoc! {r#"
+        [dependency-groups]
+        foo = ["sortedcontainers"]
+        bar = ["iniconfig"]
+        dev = ["sniffio"]
+    "#})?;
+
+    // default groups
+    uv_snapshot!(context.filters(), context.sync(), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    warning: No `requires-python` value found in the workspace. Defaulting to `>=3.12`.
+    Resolved 3 packages in [TIME]
+    Prepared 1 package in [TIME]
+    Installed 1 package in [TIME]
+     + sniffio==1.3.1
+    ");
+
+    // explicit --group
+    uv_snapshot!(context.filters(), context.sync()
+        .arg("--group").arg("bar"), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    warning: No `requires-python` value found in the workspace. Defaulting to `>=3.12`.
+    Resolved 3 packages in [TIME]
+    Prepared 1 package in [TIME]
+    Installed 1 package in [TIME]
+     + iniconfig==2.0.0
+    ");
+
+    // explicit --only-group
+    uv_snapshot!(context.filters(), context.sync()
+        .arg("--only-group").arg("foo"), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    warning: No `requires-python` value found in the workspace. Defaulting to `>=3.12`.
+    Resolved 3 packages in [TIME]
+    Prepared 1 package in [TIME]
+    Uninstalled 2 packages in [TIME]
+    Installed 1 package in [TIME]
+     - iniconfig==2.0.0
+     - sniffio==1.3.1
+     + sortedcontainers==2.4.0
+    ");
+
+    Ok(())
+}
+
 #[test]
 fn virtual_no_build_dynamic_cached() -> Result<()> {
     let context = TestContext::new("3.12");

crates/uv/tests/it/venv.rs

@@ -189,6 +189,59 @@ fn create_venv_project_environment() -> Result<()> {
     Ok(())
 }
 
+#[test]
+fn virtual_empty() -> Result<()> {
+    // testing how `uv venv` reacts to a pyproject with no `[project]` and nothing useful to it
+    let context = TestContext::new("3.12");
+
+    let pyproject_toml = context.temp_dir.child("pyproject.toml");
+    pyproject_toml.write_str(indoc! {r#"
+        [tool.mycooltool]
+        wow = "someconfig"
+    "#})?;
+
+    uv_snapshot!(context.filters(), context.venv(), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Using CPython 3.12.[X] interpreter at: [PYTHON-3.12]
+    Creating virtual environment at: .venv
+    Activate with: source .venv/[BIN]/activate
+    ");
+
+    Ok(())
+}
+
+#[test]
+fn virtual_dependency_group() -> Result<()> {
+    // testing basic `uv venv` functionality
+    // when the pyproject.toml is fully virtual (no `[project]`, but `[dependency-groups]` defined)
+    let context = TestContext::new("3.12");
+
+    let pyproject_toml = context.temp_dir.child("pyproject.toml");
+    pyproject_toml.write_str(indoc! {r#"
+        [dependency-groups]
+        foo = ["sortedcontainers"]
+        bar = ["iniconfig"]
+        dev = ["sniffio"]
+    "#})?;
+
+    uv_snapshot!(context.filters(), context.venv(), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Using CPython 3.12.[X] interpreter at: [PYTHON-3.12]
+    Creating virtual environment at: .venv
+    Activate with: source .venv/[BIN]/activate
+    ");
+
+    Ok(())
+}
+
 #[test]
 fn create_venv_defaults_to_cwd() {
     let context = TestContext::new_with_versions(&["3.12"]);

crates/uv/tests/it/version.rs

@@ -1958,3 +1958,134 @@ fn version_set_evil_constraints() -> Result<()> {
 
     Ok(())
 }
+
+#[test]
+fn virtual_empty() -> Result<()> {
+    // testing how `uv version` reacts to a pyproject with no `[project]` and nothing useful to it
+    let context = TestContext::new("3.12");
+
+    let pyproject_toml = context.temp_dir.child("pyproject.toml");
+    pyproject_toml.write_str(indoc! {r#"
+        [tool.mycooltool]
+        wow = "someconfig"
+    "#})?;
+
+    // Get version (doesn't make sense)
+    uv_snapshot!(context.filters(), context.version()
+        .arg("sortedcontainers"), @r"
+    success: false
+    exit_code: 2
+    ----- stdout -----
+
+    ----- stderr -----
+    error: Missing `project.name` field in: pyproject.toml
+    ");
+
+    let pyproject_toml = context.read("pyproject.toml");
+
+    insta::with_settings!({
+        filters => context.filters(),
+    }, {
+        assert_snapshot!(
+            pyproject_toml, @r#"
+        [tool.mycooltool]
+        wow = "someconfig"
+        "#
+        );
+    });
+
+    // Set version (can make sense, but we should still refuse?)
+    uv_snapshot!(context.filters(), context.version()
+        .arg("1.0.0"), @r"
+    success: false
+    exit_code: 2
+    ----- stdout -----
+
+    ----- stderr -----
+    error: Missing `project.name` field in: pyproject.toml
+    ");
+
+    let pyproject_toml = context.read("pyproject.toml");
+
+    insta::with_settings!({
+        filters => context.filters(),
+    }, {
+        assert_snapshot!(
+            pyproject_toml, @r#"
+        [tool.mycooltool]
+        wow = "someconfig"
+        "#
+        );
+    });
+
+    Ok(())
+}
+
+#[test]
+fn add_virtual_dependency_group() -> Result<()> {
+    // testing basic `uv version` functionality
+    // when the pyproject.toml is fully virtual (no `[project]`)
+    // But at least has some dependency-group tables (shouldn't matter to this command)
+    let context = TestContext::new("3.12");
+
+    let pyproject_toml = context.temp_dir.child("pyproject.toml");
+    pyproject_toml.write_str(indoc! {r#"
+        [dependency-groups]
+        foo = ["sortedcontainers"]
+        bar = ["iniconfig"]
+        dev = ["sniffio"]
+    "#})?;
+
+    // Get the version (doesn't make sense)
+    uv_snapshot!(context.filters(), context.version(), @r"
+    success: false
+    exit_code: 2
+    ----- stdout -----
+
+    ----- stderr -----
+    error: Missing `project.name` field in: pyproject.toml
+    ");
+
+    let pyproject_toml = context.read("pyproject.toml");
+
+    insta::with_settings!({
+        filters => context.filters(),
+    }, {
+        assert_snapshot!(
+            pyproject_toml, @r#"
+        [dependency-groups]
+        foo = ["sortedcontainers"]
+        bar = ["iniconfig"]
+        dev = ["sniffio"]
+        "#
+        );
+    });
+
+    // Set the version (can make sense, we should refuse?)
+    uv_snapshot!(context.filters(), context.version()
+        .arg("1.0.0"), @r"
+    success: false
+    exit_code: 2
+    ----- stdout -----
+
+    ----- stderr -----
+    error: Missing `project.name` field in: pyproject.toml
+    ");
+
+    let pyproject_toml = context.read("pyproject.toml");
+
+    insta::with_settings!({
+        filters => context.filters(),
+    }, {
+        assert_snapshot!(
+            pyproject_toml, @r#"
+        [dependency-groups]
+        foo = ["sortedcontainers"]
+        bar = ["iniconfig"]
+        dev = ["sniffio"]
+        "#
+        );
+    });
+
+    Ok(())
+}