20 files changed, 259 insertions, 240 deletions

diff --git a/tests/lint_tests/test_lint_changelog.py b/tests/lint_tests/test_lint_changelog.py
index 25dac0e..258c2fe 100644
--- a/tests/lint_tests/test_lint_changelog.py
+++ b/tests/lint_tests/test_lint_changelog.py
@@ -1,17 +1,11 @@
 import textwrap
-from typing import List, Optional
 
 import pytest
 
 from debputy.lsp.lsp_debian_changelog import _lint_debian_changelog
-from debputy.lsp.lsp_debian_control import _lint_debian_control
 from debputy.packages import DctrlParser
 from debputy.plugin.api.feature_set import PluginProvidedFeatureSet
-from lint_tests.lint_tutil import (
-    group_diagnostics_by_severity,
-    requires_levenshtein,
-    LintWrapper,
-)
+from lint_tests.lint_tutil import LintWrapper
 
 try:
     from lsprotocol.types import Diagnostic, DiagnosticSeverity
@@ -60,7 +54,7 @@ def test_dctrl_lint(line_linter: LintWrapper) -> None:
     
     Package: something-else
     """
-    )
+    ).splitlines(keepends=True)
 
     diagnostics = line_linter(lines)
     print(diagnostics)
@@ -73,7 +67,7 @@ def test_dctrl_lint(line_linter: LintWrapper) -> None:
 
     Package: something-else
     """
-    )
+    ).splitlines(keepends=True)
 
     diagnostics = line_linter(lines)
     print(diagnostics)
diff --git a/tests/lint_tests/test_lint_dctrl.py b/tests/lint_tests/test_lint_dctrl.py
index e9a5756..ce34d7c 100644
--- a/tests/lint_tests/test_lint_dctrl.py
+++ b/tests/lint_tests/test_lint_dctrl.py
@@ -153,6 +153,7 @@ def test_dctrl_lint_mx_value_with_typo(line_linter: LintWrapper) -> None:
 
     diagnostics = line_linter(lines)
     print(diagnostics)
+    assert diagnostics is not None
     assert len(diagnostics) == 2
     by_severity = group_diagnostics_by_severity(diagnostics)
     assert DiagnosticSeverity.Error in by_severity
diff --git a/tests/lint_tests/test_lint_debputy.py b/tests/lint_tests/test_lint_debputy.py
index 9c30392..8e405f8 100644
--- a/tests/lint_tests/test_lint_debputy.py
+++ b/tests/lint_tests/test_lint_debputy.py
@@ -1,187 +1,4 @@
-from typing import List, Optional, Callable
-
-import pytest
-
-from debputy.packages import DctrlParser
-from debputy.plugin.api.feature_set import PluginProvidedFeatureSet
-from lint_tests.lint_tutil import (
-    requires_levenshtein,
-    LintWrapper,
-)
-
-try:
-    from lsprotocol.types import Diagnostic, DiagnosticSeverity
-except ImportError:
-    pass
-
-
-@pytest.fixture
-def line_linter(
-    debputy_plugin_feature_set: PluginProvidedFeatureSet,
-    lint_dctrl_parser: DctrlParser,
-) -> LintWrapper:
-    return LintWrapper(
-        "/nowhere/debian/debputy.manifest",
-        _lint_debian_debputy_manifest,
-        debputy_plugin_feature_set,
-        lint_dctrl_parser,
-    )
-
-
-def test_debputy_lint_unknown_keys(line_linter: LintWrapper) -> None:
-    lines = textwrap.dedent(
-        """\
-    manifest-version: 0.1
-    installations:
-    - install-something:
-        sources:
-        - abc
-        - def
-    - install-docs:
-        source: foo
-        puff: true   # Unknown keyword (assuming install-docs)
-        when:
-          negated: cross-compiling
-    - install-docs:
-        source: bar
-        when: ross-compiling  # Typo of "cross-compiling"; FIXME not caught
-    packages:
-      foo:
-        blah: qwe    # Unknown keyword
-    """
-    ).splitlines(keepends=True)
-
-    diagnostics = line_linter(lines)
-    by_severity = group_diagnostics_by_severity(diagnostics)
-    # This example triggers errors only
-    assert DiagnosticSeverity.Error in by_severity
-
-    assert DiagnosticSeverity.Warning not in by_severity
-    assert DiagnosticSeverity.Hint not in by_severity
-    assert DiagnosticSeverity.Information not in by_severity
-
-    errors = by_severity[DiagnosticSeverity.Error]
-    print(errors)
-    assert len(errors) == 4
-
-    first_error, second_error, third_error, fourth_error = errors
-
-    msg = 'Unknown or unsupported key "install-something".'
-    assert first_error.message == msg
-    assert f"{first_error.range}" == "2:2-2:19"
-
-    msg = 'Unknown or unsupported key "puff".'
-    assert second_error.message == msg
-    assert f"{second_error.range}" == "8:4-8:8"
-
-    msg = 'Unknown or unsupported key "negated".'
-    assert third_error.message == msg
-    assert f"{third_error.range}" == "10:6-10:13"
-
-    msg = 'Unknown or unsupported key "blah".'
-    assert fourth_error.message == msg
-    assert f"{fourth_error.range}" == "16:4-16:8"
-
-
-@requires_levenshtein
-def test_debputy_lint_unknown_keys_spelling(line_linter: LintWrapper) -> None:
-    lines = textwrap.dedent(
-        """\
-    manifest-version: 0.1
-    installations:
-    - install-dcoss:  # typo
-        sources:
-        - abc
-        - def
-        puff: true   # Unknown keyword (assuming install-docs)
-        when:
-          nut: cross-compiling  # Typo of "not"
-    - install-docs:
-        source: bar
-        when: ross-compiling  # Typo of "cross-compiling"; FIXME not caught
-    """
-    ).splitlines(keepends=True)
-
-    diagnostics = line_linter(lines)
-    by_severity = group_diagnostics_by_severity(diagnostics)
-    # This example triggers errors only
-    assert DiagnosticSeverity.Error in by_severity
-
-    assert DiagnosticSeverity.Warning not in by_severity
-    assert DiagnosticSeverity.Hint not in by_severity
-    assert DiagnosticSeverity.Information not in by_severity
-
-    errors = by_severity[DiagnosticSeverity.Error]
-    print(errors)
-    assert len(errors) == 3
-
-    first_error, second_error, third_error = errors
-
-    msg = 'Unknown or unsupported key "install-dcoss". It looks like a typo of "install-docs".'
-    assert first_error.message == msg
-    assert f"{first_error.range}" == "2:2-2:15"
-
-    msg = 'Unknown or unsupported key "puff".'
-    assert second_error.message == msg
-    assert f"{second_error.range}" == "6:4-6:8"
-
-    msg = 'Unknown or unsupported key "nut". It looks like a typo of "not".'
-    assert third_error.message == msg
-    assert f"{third_error.range}" == "8:6-8:9"
-
-
-def test_debputy_lint_conflicting_keys(line_linter: LintWrapper) -> None:
-    lines = textwrap.dedent(
-        """\
-    manifest-version: 0.1
-    installations:
-    - install-docs:
-        sources:
-        - foo
-        - bar
-        as: baz      # Conflicts with "sources" (#85)
-    - install:
-        source: foo
-        sources:     # Conflicts with "source" (#85)
-        - bar
-        - baz
-    """
-    ).splitlines(keepends=True)
-
-    diagnostics = line_linter(lines)
-    by_severity = group_diagnostics_by_severity(diagnostics)
-    # This example triggers errors only
-    assert DiagnosticSeverity.Error in by_severity
-
-    assert DiagnosticSeverity.Warning not in by_severity
-    assert DiagnosticSeverity.Hint not in by_severity
-    assert DiagnosticSeverity.Information not in by_severity
-
-    errors = by_severity[DiagnosticSeverity.Error]
-    print(errors)
-    assert len(errors) == 4
-
-    first_error, second_error, third_error, fourth_error = errors
-
-    msg = 'The "sources" cannot be used with "as".'
-    assert first_error.message == msg
-    assert f"{first_error.range}" == "3:4-3:11"
-
-    msg = 'The "as" cannot be used with "sources".'
-    assert second_error.message == msg
-    assert f"{second_error.range}" == "6:4-6:6"
-
-    msg = 'The "source" cannot be used with "sources".'
-    assert third_error.message == msg
-    assert f"{third_error.range}" == "8:4-8:10"
-
-    msg = 'The "sources" cannot be used with "source".'
-    assert fourth_error.message == msg
-    assert f"{fourth_error.range}" == "9:4-9:11"
-
-
 import textwrap
-from typing import List, Optional, Callable
 
 import pytest
 
@@ -189,9 +6,9 @@ from debputy.lsp.lsp_debian_debputy_manifest import _lint_debian_debputy_manifes
 from debputy.packages import DctrlParser
 from debputy.plugin.api.feature_set import PluginProvidedFeatureSet
 from lint_tests.lint_tutil import (
-    group_diagnostics_by_severity,
     requires_levenshtein,
     LintWrapper,
+    group_diagnostics_by_severity,
 )
 
 try:
@@ -199,8 +16,6 @@ try:
 except ImportError:
     pass
 
-TestLintWrapper = Callable[[List[str]], Optional[List["Diagnostic"]]]
-
 
 @pytest.fixture
 def line_linter(
diff --git a/tests/lsp_tests/lsp_tutil.py b/tests/lsp_tests/lsp_tutil.py
index 0843f79..bc0fa91 100644
--- a/tests/lsp_tests/lsp_tutil.py
+++ b/tests/lsp_tests/lsp_tutil.py
@@ -1,16 +1,52 @@
-from typing import Tuple, Union
+import dataclasses
+from typing import Tuple, Union, FrozenSet, Optional, List
+
+from debputy.lsp.lsp_features import SEMANTIC_TOKENS_LEGEND
+from debputy.util import grouper
 
 try:
-    from pygls.server import LanguageServer
     from lsprotocol.types import (
         TextDocumentItem,
         Position,
+        Range,
+        SemanticTokens,
     )
     from debputy.lsp.debputy_ls import DebputyLanguageServer
 except ImportError:
     pass
 
 
+@dataclasses.dataclass(slots=True, frozen=True)
+class ResolvedSemanticToken:
+    range: "Range"
+    token_name: str
+    modifiers: FrozenSet[str] = frozenset()
+
+
+def resolved_semantic_token(
+    line_no: int,
+    col_start: int,
+    token_len: int,
+    token_type: str,
+    *,
+    token_modifiers: FrozenSet[str] = frozenset(),
+) -> ResolvedSemanticToken:
+    return ResolvedSemanticToken(
+        Range(
+            Position(
+                line_no,
+                col_start,
+            ),
+            Position(
+                line_no,
+                col_start + token_len,
+            ),
+        ),
+        token_type,
+        token_modifiers,
+    )
+
+
 def _locate_cursor(text: str) -> Tuple[str, "Position"]:
     lines = text.splitlines(keepends=True)
     for line_no in range(len(lines)):
@@ -27,12 +63,27 @@ def _locate_cursor(text: str) -> Tuple[str, "Position"]:
 
 
 def put_doc_with_cursor(
-    ls: Union["LanguageServer", "DebputyLanguageServer"],
+    ls: "DebputyLanguageServer",
     uri: str,
     language_id: str,
     content: str,
 ) -> "Position":
     cleaned_content, cursor_pos = _locate_cursor(content)
+    put_doc_no_cursor(
+        ls,
+        uri,
+        language_id,
+        cleaned_content,
+    )
+    return cursor_pos
+
+
+def put_doc_no_cursor(
+    ls: "DebputyLanguageServer",
+    uri: str,
+    language_id: str,
+    content: str,
+) -> None:
     doc_version = 1
     existing = ls.workspace.text_documents.get(uri)
     if existing is not None:
@@ -42,7 +93,38 @@ def put_doc_with_cursor(
             uri,
             language_id,
             doc_version,
-            cleaned_content,
+            content,
         )
     )
-    return cursor_pos
+
+
+def resolve_semantic_tokens(
+    token_result: Optional["SemanticTokens"],
+) -> Optional[List[ResolvedSemanticToken]]:
+    if token_result is None:
+        return None
+    assert (len(token_result.data) % 5) == 0
+    current_line = 0
+    current_col = 0
+    resolved_tokens = []
+    token_types = SEMANTIC_TOKENS_LEGEND.token_types
+    for token_data in grouper(token_result.data, 5, incomplete="strict"):
+        line_delta, col_start_delta, token_len, token_code, modifier_codes = token_data
+        if line_delta:
+            current_col = 0
+        current_line += line_delta
+        current_col += col_start_delta
+        assert (
+            not modifier_codes
+        ), "TODO: Modifiers not supported (no modifiers defined)"
+
+        resolved_tokens.append(
+            resolved_semantic_token(
+                current_line,
+                current_col,
+                token_len,
+                token_types[token_code],
+            ),
+        )
+
+    return resolved_tokens
diff --git a/tests/lsp_tests/test_debpkg_metadata.py b/tests/lsp_tests/test_debpkg_metadata.py
new file mode 100644
index 0000000..f784b0a
--- /dev/null
+++ b/tests/lsp_tests/test_debpkg_metadata.py
@@ -0,0 +1,25 @@
+from typing import Optional
+
+import pytest
+
+from debputy.lsp.lsp_debian_control_reference_data import package_name_to_section
+
+
+@pytest.mark.parametrize(
+    "name,guessed_section",
+    [
+        ("foo-udeb", "debian-installer"),
+        ("python-foo", "python"),
+        ("python-foo-doc", "doc"),
+        ("libfoo-dev", "libdevel"),
+        ("php-foo", "php"),
+        ("libpam-foo", "admin"),
+        ("fonts-foo", "fonts"),
+        ("xxx-l10n", "localization"),
+        ("xxx-l10n-bar", "localization"),
+        ("libfoo4", "libs"),
+        ("unknown", None),
+    ]
+)
+def test_package_name_to_section(name: str, guessed_section: Optional[str]) -> None:
+    assert package_name_to_section(name) == guessed_section
diff --git a/tests/lsp_tests/test_lsp_dctrl.py b/tests/lsp_tests/test_lsp_dctrl.py
index 122b929..2bc90ba 100644
--- a/tests/lsp_tests/test_lsp_dctrl.py
+++ b/tests/lsp_tests/test_lsp_dctrl.py
@@ -1,25 +1,34 @@
 import textwrap
 
+from debputy.lsp.debputy_ls import DebputyLanguageServer
+
 try:
     from lsprotocol.types import (
         CompletionParams,
         TextDocumentIdentifier,
         HoverParams,
         MarkupContent,
+        SemanticTokensParams,
     )
 
     from debputy.lsp.lsp_debian_control import (
         _debian_control_completions,
         _debian_control_hover,
+        _debian_control_semantic_tokens_full,
     )
 
     from pygls.server import LanguageServer
 except ImportError:
     pass
-from lsp_tests.lsp_tutil import put_doc_with_cursor
+from lsp_tests.lsp_tutil import (
+    put_doc_with_cursor,
+    put_doc_no_cursor,
+    resolve_semantic_tokens,
+    resolved_semantic_token,
+)
 
 
-def test_dctrl_complete_field(ls: "LanguageServer") -> None:
+def test_dctrl_complete_field(ls: "DebputyLanguageServer") -> None:
     dctrl_uri = "file:///nowhere/debian/control"
 
     cursor_pos = put_doc_with_cursor(
@@ -48,7 +57,7 @@ def test_dctrl_complete_field(ls: "LanguageServer") -> None:
     assert "Source" not in keywords
 
 
-def test_dctrl_hover_doc_field(ls: "LanguageServer") -> None:
+def test_dctrl_hover_doc_field(ls: "DebputyLanguageServer") -> None:
     dctrl_uri = "file:///nowhere/debian/control"
     cursor_pos = put_doc_with_cursor(
         ls,
@@ -72,7 +81,7 @@ def test_dctrl_hover_doc_field(ls: "LanguageServer") -> None:
     assert "Determines which architecture" in hover_doc.contents.value
 
 
-def test_dctrl_hover_doc_synopsis(ls: "LanguageServer") -> None:
+def test_dctrl_hover_doc_synopsis(ls: "DebputyLanguageServer") -> None:
     dctrl_uri = "file:///nowhere/debian/control"
     cursor_pos = put_doc_with_cursor(
         ls,
@@ -98,7 +107,7 @@ def test_dctrl_hover_doc_synopsis(ls: "LanguageServer") -> None:
     assert "super charged tool with batteries included" in hover_doc.contents.value
 
 
-def test_dctrl_hover_doc_substvars(ls: "LanguageServer") -> None:
+def test_dctrl_hover_doc_substvars(ls: "DebputyLanguageServer") -> None:
     dctrl_uri = "file:///nowhere/debian/control"
     matching_cases = [
         "bar (= <CURSOR>${binary:Version})",
@@ -158,3 +167,54 @@ def test_dctrl_hover_doc_substvars(ls: "LanguageServer") -> None:
         if hover_doc is not None and isinstance(hover_doc.contents, MarkupContent):
             provided_doc = hover_doc.contents.value
         assert not provided_doc.startswith("# Substvar `${binary:Version}`")
+
+
+def test_dctrl_semantic_tokens(ls: "DebputyLanguageServer") -> None:
+    dctrl_uri = "file:///nowhere/debian/control"
+    put_doc_no_cursor(
+        ls,
+        dctrl_uri,
+        "debian/control",
+        textwrap.dedent(
+            """\
+        # Some leading comment
+
+        Source: foo
+
+        # Comment between stanzas
+
+        Package: foo
+        # Comment before Architecture
+        Architecture: any
+        Depends:
+        # Comment about bar
+             bar (>= 1.0),
+             baz [linux-any] <!pkg.foo.bootstrap>
+        Description: super charged tool with batteries included
+        Unknown-Field: Some value
+        # Comment in that field
+          that we do not know about.
+"""
+        ),
+    )
+
+    semantic_tokens = _debian_control_semantic_tokens_full(
+        ls,
+        SemanticTokensParams(TextDocumentIdentifier(dctrl_uri)),
+    )
+    resolved_semantic_tokens = resolve_semantic_tokens(semantic_tokens)
+    assert resolved_semantic_tokens is not None
+    assert resolved_semantic_tokens == [
+        resolved_semantic_token(0, 0, len("# Some leading comment"), "comment"),
+        resolved_semantic_token(2, 0, len("Source"), "keyword"),
+        resolved_semantic_token(4, 0, len("# Comment between stanzas"), "comment"),
+        resolved_semantic_token(6, 0, len("Package"), "keyword"),
+        resolved_semantic_token(7, 0, len("# Comment before Architecture"), "comment"),
+        resolved_semantic_token(8, 0, len("Architecture"), "keyword"),
+        resolved_semantic_token(8, len("Architecture: "), len("any"), "enumMember"),
+        resolved_semantic_token(9, 0, len("Depends"), "keyword"),
+        resolved_semantic_token(10, 0, len("# Comment about bar"), "comment"),
+        resolved_semantic_token(13, 0, len("Description"), "keyword"),
+        resolved_semantic_token(14, 0, len("Unknown-Field"), "keyword"),
+        # TODO: resolved_semantic_token(15, 0, len("# Comment in that field"), "comment"),
+    ]
diff --git a/tests/lsp_tests/test_lsp_debputy_manifest_hover.py b/tests/lsp_tests/test_lsp_debputy_manifest_hover.py
index c66db80..54c6b6a 100644
--- a/tests/lsp_tests/test_lsp_debputy_manifest_hover.py
+++ b/tests/lsp_tests/test_lsp_debputy_manifest_hover.py
@@ -2,6 +2,7 @@ import textwrap
 
 import pytest
 
+from debputy.lsp.debputy_ls import DebputyLanguageServer
 from lsp_tests.lsp_tutil import put_doc_with_cursor
 
 try:
@@ -25,7 +26,7 @@ except ImportError:
     HAS_PYGLS = False
 
 
-def test_basic_debputy_hover_tlk(ls: "LanguageServer") -> None:
+def test_basic_debputy_hover_tlk(ls: "DebputyLanguageServer") -> None:
     debputy_manifest_uri = "file:///nowhere/debian/debputy.manifest"
     cursor_pos = put_doc_with_cursor(
         ls,
@@ -52,7 +53,7 @@ def test_basic_debputy_hover_tlk(ls: "LanguageServer") -> None:
     assert hover_doc.contents.value.startswith("Installations")
 
 
-def test_basic_debputy_hover_install_docs_key(ls: "LanguageServer") -> None:
+def test_basic_debputy_hover_install_docs_key(ls: "DebputyLanguageServer") -> None:
     debputy_manifest_uri = "file:///nowhere/debian/debputy.manifest"
     cursor_pos = put_doc_with_cursor(
         ls,
@@ -79,7 +80,7 @@ def test_basic_debputy_hover_install_docs_key(ls: "LanguageServer") -> None:
     assert hover_doc.contents.value.startswith("Install documentation (`install-docs`)")
 
 
-def test_basic_debputy_hover_install_docs_sources(ls: "LanguageServer") -> None:
+def test_basic_debputy_hover_install_docs_sources(ls: "DebputyLanguageServer") -> None:
     debputy_manifest_uri = "file:///nowhere/debian/debputy.manifest"
     cursor_pos = put_doc_with_cursor(
         ls,
@@ -106,7 +107,7 @@ def test_basic_debputy_hover_install_docs_sources(ls: "LanguageServer") -> None:
     assert hover_doc.contents.value.startswith("# Attribute `sources`")
 
 
-def test_basic_debputy_hover_install_docs_when(ls: "LanguageServer") -> None:
+def test_basic_debputy_hover_install_docs_when(ls: "DebputyLanguageServer") -> None:
     debputy_manifest_uri = "file:///nowhere/debian/debputy.manifest"
     cursor_pos = put_doc_with_cursor(
         ls,
@@ -134,7 +135,7 @@ def test_basic_debputy_hover_install_docs_when(ls: "LanguageServer") -> None:
     assert hover_doc.contents.value.startswith("# Attribute `when`")
 
 
-def test_basic_debputy_hover_install_docs_str_cond(ls: "LanguageServer") -> None:
+def test_basic_debputy_hover_install_docs_str_cond(ls: "DebputyLanguageServer") -> None:
     debputy_manifest_uri = "file:///nowhere/debian/debputy.manifest"
     cursor_pos = put_doc_with_cursor(
         ls,
@@ -165,7 +166,7 @@ def test_basic_debputy_hover_install_docs_str_cond(ls: "LanguageServer") -> None
 
 
 def test_basic_debputy_hover_install_docs_mapping_cond_key(
-    ls: "LanguageServer",
+    ls: "DebputyLanguageServer",
 ) -> None:
     debputy_manifest_uri = "file:///nowhere/debian/debputy.manifest"
     cursor_pos = put_doc_with_cursor(
@@ -197,7 +198,7 @@ def test_basic_debputy_hover_install_docs_mapping_cond_key(
 
 @pytest.mark.xfail
 def test_basic_debputy_hover_install_docs_mapping_cond_str_value(
-    ls: "LanguageServer",
+    ls: "DebputyLanguageServer",
 ) -> None:
     debputy_manifest_uri = "file:///nowhere/debian/debputy.manifest"
     cursor_pos = put_doc_with_cursor(
@@ -230,7 +231,7 @@ def test_basic_debputy_hover_install_docs_mapping_cond_str_value(
     )
 
 
-def test_basic_debputy_hover_binary_version(ls: "LanguageServer") -> None:
+def test_basic_debputy_hover_binary_version(ls: "DebputyLanguageServer") -> None:
     debputy_manifest_uri = "file:///nowhere/debian/debputy.manifest"
     cursor_pos = put_doc_with_cursor(
         ls,
@@ -256,7 +257,7 @@ def test_basic_debputy_hover_binary_version(ls: "LanguageServer") -> None:
     )
 
 
-def test_basic_debputy_hover_services(ls: "LanguageServer") -> None:
+def test_basic_debputy_hover_services(ls: "DebputyLanguageServer") -> None:
     debputy_manifest_uri = "file:///nowhere/debian/debputy.manifest"
     cursor_pos = put_doc_with_cursor(
         ls,
@@ -283,7 +284,7 @@ def test_basic_debputy_hover_services(ls: "LanguageServer") -> None:
     )
 
 
-def test_basic_debputy_hover_services_service(ls: "LanguageServer") -> None:
+def test_basic_debputy_hover_services_service(ls: "DebputyLanguageServer") -> None:
     debputy_manifest_uri = "file:///nowhere/debian/debputy.manifest"
     cursor_pos = put_doc_with_cursor(
         ls,
diff --git a/tests/plugin_tests/__init__.py b/tests/plugin_tests/__init__.py
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/tests/plugin_tests/__init__.py
diff --git a/tests/plugin_tests/conftest.py b/tests/plugin_tests/conftest.py
index f2a8aea..6b28755 100644
--- a/tests/plugin_tests/conftest.py
+++ b/tests/plugin_tests/conftest.py
@@ -1,10 +1,11 @@
 import os
+from typing import Iterator
 
 import pytest
 
 
 @pytest.fixture(autouse=True)
-def workaround_debputys_own_test_suite() -> None:
+def workaround_debputys_own_test_suite() -> Iterator[None]:
     # This fixture is only required as long as the tests are run inside `debputy`'s
     # own test suite.  If you copy out a plugin + tests, you should *not* need this
     # fixture.
diff --git a/tests/plugin_tests/numpy3_test.py b/tests/plugin_tests/numpy3_test.py
index 9b252fb..62fbd77 100644
--- a/tests/plugin_tests/numpy3_test.py
+++ b/tests/plugin_tests/numpy3_test.py
@@ -1,4 +1,5 @@
 import os
+from typing import Iterator
 
 import pytest
 
@@ -12,7 +13,7 @@ DATA_FILE = os.path.join(os.path.dirname(__file__), "numpy3_test.data")
 
 
 @pytest.fixture(scope="session")
-def numpy3_stub_data_file() -> None:
+def numpy3_stub_data_file() -> Iterator[None]:
     os.environ["_NUMPY_TEST_PATH"] = DATA_FILE
     yield
     try:
diff --git a/tests/plugin_tests/perl-openssl_test.py b/tests/plugin_tests/perl-openssl_test.py
index 37f2ba1..27d680d 100644
--- a/tests/plugin_tests/perl-openssl_test.py
+++ b/tests/plugin_tests/perl-openssl_test.py
@@ -1,5 +1,6 @@
 import stat
 import os
+from typing import Iterator
 
 import pytest
 
@@ -13,7 +14,7 @@ STUB_CMD = os.path.join(os.path.dirname(__file__), "perl-ssl_test.sh")
 
 
 @pytest.fixture(scope="session")
-def perl_ssl_stub_cmd() -> None:
+def perl_ssl_stub_cmd() -> Iterator[None]:
     os.environ["_PERL_SSL_DEFAULTS_TEST_PATH"] = STUB_CMD
     mode = stat.S_IMODE(os.stat(STUB_CMD).st_mode)
     if (mode & 0o500) != 0o500:
diff --git a/tests/test_alternatives.py b/tests/test_alternatives.py
index 2a42d69..c395dab 100644
--- a/tests/test_alternatives.py
+++ b/tests/test_alternatives.py
@@ -79,6 +79,8 @@ def test_alternatives(
     prerm = maintscript_snippets["prerm"].generate_snippet(reverse=True)
     postinst = maintscript_snippets["postinst"].generate_snippet(reverse=True)
 
+    assert prerm is not None
+    assert postinst is not None
     assert "--remove x-terminal-emulator /usr/bin/xterm" in prerm
     assert (
         "--install /usr/bin/x-terminal-emulator x-terminal-emulator /usr/bin/xterm 20"
diff --git a/tests/test_deb_packaging_support.py b/tests/test_deb_packaging_support.py
index d47526d..e4e13da 100644
--- a/tests/test_deb_packaging_support.py
+++ b/tests/test_deb_packaging_support.py
@@ -203,9 +203,9 @@ def test_upstream_changelog_salsa_issue_49(
 ) -> None:
     # https://salsa.debian.org/debian/debputy/-/issues/49
     dctrl = package_single_foo_arch_all_cxt_amd64["foo"]
-    doc_dir = f"./usr/share/doc/{dctrl.name}"
+    doc_dir_path = f"./usr/share/doc/{dctrl.name}"
     data_fs_root = build_virtual_fs(
-        [virtual_path_def(f"{doc_dir}", link_target="foo-data")], read_write_fs=True
+        [virtual_path_def(doc_dir_path, link_target="foo-data")], read_write_fs=True
     )
     source_fs_root = build_virtual_fs(
         [virtual_path_def("changelog", materialized_content="Wrong file!")]
diff --git a/tests/test_debputy_plugin.py b/tests/test_debputy_plugin.py
index a5d7758..dc60597 100644
--- a/tests/test_debputy_plugin.py
+++ b/tests/test_debputy_plugin.py
@@ -1,6 +1,6 @@
 import os
 import textwrap
-from typing import Sequence
+from typing import Sequence, Any, List, Optional
 
 import pytest
 
@@ -643,6 +643,8 @@ def test_system_service_detection() -> None:
     systemd_service_system_dir = f"{systemd_service_root_dir}/system"
     systemd_service_user_dir = f"{systemd_service_root_dir}/user"
 
+    services: List[DetectedService[Optional[object]]]
+
     services, _ = plugin.run_service_detection_and_integrations(
         "systemd", build_virtual_file_system([])
     )
@@ -704,7 +706,9 @@ def test_system_service_detection() -> None:
     assert foo_service.enable_by_default
     assert foo_service.start_by_default
     assert foo_service.default_upgrade_rule == "restart"
-    assert foo_service.service_context.had_install_section
+    foo_service_context = foo_service.service_context
+    assert isinstance(foo_service_context, SystemdServiceContext)
+    assert foo_service_context.had_install_section
 
     bar_timer = _extract_service(services, "bar.timer")
     assert set(bar_timer.names) == {"bar.timer"}
@@ -713,7 +717,9 @@ def test_system_service_detection() -> None:
     assert not bar_timer.enable_by_default
     assert bar_timer.start_by_default
     assert bar_timer.default_upgrade_rule == "restart"
-    assert not bar_timer.service_context.had_install_section
+    bar_service_context = bar_timer.service_context
+    assert isinstance(bar_service_context, SystemdServiceContext)
+    assert not bar_service_context.had_install_section
 
     snippets = metadata.maintscripts()
     assert len(snippets) == 4
@@ -742,6 +748,8 @@ def test_sysv_service_detection() -> None:
     )
     init_dir = "etc/init.d"
 
+    services: List[DetectedService[Optional[object]]]
+
     services, _ = plugin.run_service_detection_and_integrations(
         "sysvinit", build_virtual_file_system([])
     )
@@ -1135,9 +1143,9 @@ def test_pam_auth_update() -> None:
     assert postinst.registration_method == "on_configure"
     assert "pam-auth-update --package" in postinst.plugin_provided_script
 
-    prerms = prerms[0]
-    assert prerms.registration_method == "on_before_removal"
-    assert "pam-auth-update --package --remove foo-pam" in prerms.plugin_provided_script
+    prerm = prerms[0]
+    assert prerm.registration_method == "on_before_removal"
+    assert "pam-auth-update --package --remove foo-pam" in prerm.plugin_provided_script
 
 
 def test_auto_depends_solink() -> None:
diff --git a/tests/test_declarative_parser.py b/tests/test_declarative_parser.py
index 94341ea..26291dd 100644
--- a/tests/test_declarative_parser.py
+++ b/tests/test_declarative_parser.py
@@ -1,4 +1,11 @@
-from typing import List, TypedDict, NotRequired, Annotated, Union, Mapping
+from typing import (
+    List,
+    TypedDict,
+    NotRequired,
+    Annotated,
+    Union,
+    Mapping,
+)
 
 import pytest
 
@@ -25,7 +32,7 @@ class TFinalEntity(DebputyParsedContent):
 
 class TSourceEntity(TypedDict):
     sources: NotRequired[List[str]]
-    source: Annotated[NotRequired[str], DebputyParseHint.target_attribute("sources")]
+    source: NotRequired[Annotated[str, DebputyParseHint.target_attribute("sources")]]
     as_: NotRequired[
         Annotated[
             str,
diff --git a/tests/test_fs_metadata.py b/tests/test_fs_metadata.py
index 14a397f..f32afb0 100644
--- a/tests/test_fs_metadata.py
+++ b/tests/test_fs_metadata.py
@@ -1,11 +1,13 @@
 import dataclasses
 import textwrap
-from typing import Tuple, List, Optional, Union
+from typing import Tuple, List, Optional, Union, Sequence
 
 import pytest
 
 from debputy.filesystem_scan import PathDef, build_virtual_fs
-from debputy.highlevel_manifest_parser import YAMLManifestParser
+from debputy.highlevel_manifest_parser import (
+    YAMLManifestParser,
+)
 from debputy.intermediate_manifest import PathType, IntermediateManifest, TarMember
 from debputy.plugin.api import virtual_path_def
 from debputy.plugin.api.test_api import build_virtual_file_system
@@ -57,7 +59,7 @@ def _has_fs_path(tm: TarMember) -> bool:
 
 def verify_paths(
     intermediate_manifest: IntermediateManifest,
-    expected_results: List[Tuple[Union[str, PathDef], Expected]],
+    expected_results: Sequence[Tuple[Union[str, PathDef], Expected]],
 ) -> None:
     result = {tm.member_path: tm for tm in intermediate_manifest}
     expected_table = {
@@ -89,7 +91,9 @@ def verify_paths(
             assert tm.member_path in expected_table
 
 
-def test_mtime_clamp_and_builtin_dir_mode(manifest_parser_pkg_foo):
+def test_mtime_clamp_and_builtin_dir_mode(
+    manifest_parser_pkg_foo: YAMLManifestParser,
+) -> None:
     manifest = manifest_parser_pkg_foo.build_manifest()
     claim_mtime_to = 255
     path_defs: List[Tuple[PathDef, Expected]] = [
diff --git a/tests/test_interpreter.py b/tests/test_interpreter.py
index 6cbfd44..154ee4a 100644
--- a/tests/test_interpreter.py
+++ b/tests/test_interpreter.py
@@ -82,7 +82,7 @@ def test_interpreter_detection(
 ) -> None:
     interpreter = extract_shebang_interpreter(raw_shebang)
     # The `and ...` part is just to get the raw line in the error message
-    assert interpreter is not None or raw_shebang == b""
+    assert interpreter is not None
 
     assert interpreter.original_command == original_command
     assert interpreter.command_full_basename == command_full_basename
@@ -147,11 +147,11 @@ def test_interpreter_rewrite(empty_manifest: HighLevelManifest) -> None:
     foo = fs_root.lookup("usr/bin/foo")
     foo_sh = fs_root.lookup("usr/bin/foo.sh")
 
-    assert foo.is_file
+    assert foo is not None and foo.is_file
     with foo.open() as fd:
         assert fd.read() == "random data"
 
-    assert foo_sh.is_file
+    assert foo_sh is not None and foo_sh.is_file
     with foo_sh.open() as fd:
         expected = textwrap.dedent(
             """\
diff --git a/tests/test_migrations.py b/tests/test_migrations.py
index cbf3f79..9d43549 100644
--- a/tests/test_migrations.py
+++ b/tests/test_migrations.py
@@ -119,8 +119,10 @@ def _assert_unsupported_feature(
 
 
 def _write_manifest(manifest: HighLevelManifest) -> str:
+    mutable_manifest = manifest.mutable_manifest
+    assert mutable_manifest is not None
     with io.StringIO() as fd:
-        manifest.mutable_manifest.write_to(fd)
+        mutable_manifest.write_to(fd)
         return fd.getvalue()
 
 
@@ -134,7 +136,7 @@ def _verify_migrator_generates_parsable_manifest(
     expected_warnings: Optional[List[str]] = None,
     expected_renamed_paths: Optional[List[Tuple[str, str]]] = None,
     expected_removals: Optional[List[str]] = None,
-    required_plugins: Optional[Sequence[str]] = tuple(),
+    required_plugins: Sequence[str] = tuple(),
     dh_config_mode: Optional[int] = None,
 ) -> None:
     # No file, no changes
diff --git a/tests/test_packager_provided_files.py b/tests/test_packager_provided_files.py
index 149564d..b0e075f 100644
--- a/tests/test_packager_provided_files.py
+++ b/tests/test_packager_provided_files.py
@@ -1,5 +1,5 @@
 import random
-from typing import cast
+from typing import cast, TYPE_CHECKING
 
 import pytest
 
@@ -10,9 +10,17 @@ from debputy.plugin.api.test_api import (
     InitializedPluginUnderTest,
     build_virtual_file_system,
 )
-from debputy.plugin.api.test_api.test_impl import initialize_plugin_under_test_preloaded
+from debputy.plugin.api.test_api.test_impl import (
+    initialize_plugin_under_test_preloaded,
+)
 from tutil import faked_binary_package, binary_package_table
 
+if TYPE_CHECKING:
+    from debputy.plugin.api.test_api.test_impl import InitializedPluginUnderTestImpl
+
+    # Irrelevant, but makes the import not "unused" for things that does not parse `cast("...", ...)` expressions
+    assert InitializedPluginUnderTestImpl is not None
+
 
 def ppf_test_plugin(api: DebputyPluginInitializer) -> None:
     api.packager_provided_file(
diff --git a/tests/test_plugin_tester.py b/tests/test_plugin_tester.py
index 8078a02..b41f8a3 100644
--- a/tests/test_plugin_tester.py
+++ b/tests/test_plugin_tester.py
@@ -1,6 +1,6 @@
 import json
 import os.path
-from typing import List, Tuple, Type, cast
+from typing import List, Tuple, Type, cast, TYPE_CHECKING
 
 import pytest
 
@@ -25,6 +25,13 @@ from debputy.plugin.api.test_api.test_impl import (
     initialize_plugin_under_test_from_inline_json,
 )
 
+if TYPE_CHECKING:
+    from debputy.plugin.api import PluginInitializationEntryPoint
+
+    # Irrelevant, but makes the import not "unused" for things that does not parse `cast("...", ...)` expressions
+    assert PluginInitializationEntryPoint is not None
+
+
 CUSTOM_PLUGIN_JSON_FILE = os.path.join(
     os.path.dirname(__file__), "data", "custom-plugin.json.in"
 )