Use the open-source free `coverlet` toolchain for .NET code coverage.
Test Trait Tagging
Classifies existing tests by standard traits and reports their distribution. MUST USE to categorize/tag/label tests, compare happy vs error paths, audit the test mix, or describe coverage shape by test type. Read bodies when names mislead. Apply canonical attributes; otherwise report only. DO NOT USE for test-quality audits, executed coverage or CRAP, behavioral gaps, writing tests, or migration.
Workflow
Step 1: Detect the language, framework, and tagging capability
Identify the codebase's language and test framework. Call the test-analysis-extensions skill and read the matching extension file. The extension file declares a tag-support capability for each framework:
- `auto-edit` — framework has canonical tag syntax this skill can safely insert (.NET
[TestCategory]/[Trait]/[Category]/[Property], pytest@pytest.mark.<name>, JUnit 5@Tag("..."), TestNGgroups = {"..."}, RSpec metadatait "..." , :tag => true, Pester-Tag '...', Kotest@Tags(...), Swift Testing@Tag(.tagName), Catch2[tag], doctest* doctest::test_suite("tag")decorator). - `report-only` — framework has no canonical, agreed-upon tag attribute; report tags in a Markdown table only and do not edit source (Go standard
testingwithout build-tag conventions, Jest/Vitest without consistent describe-prefix convention, Rust without project-specific cfg conventions, XCTest without a test plan, GoogleTest without test-name prefix conventions, Mocha without describe-prefix conventions). - `convention-based` — framework uses naming or file conventions for tagging (Go
//go:build integrationbuild tags, file-name suffixes like*_integration_test.go, GoogleTestINTEGRATION_*filter prefix). Only emit canonical edits when the user has confirmed the project convention; otherwise treat asreport-only.
Capture the capability before Step 4.
Step 2: Scan existing traits
Check which tests already have trait attributes. Use the loaded language extension as the source of truth — examples:
| Framework | Existing Attribute | Example | |-----------|--------------------|---------| | MSTest | [TestCategory("...")] | [TestCategory("positive")] | | xUnit | [Trait("Category", "...")] | [Trait("Category", "positive")] | | NUnit | [Category("...")] | [Category("positive")] | | TUnit | [Property("Category", "...")] | [Property("Category", "positive")] | | JUnit 5 | @Tag("...") | @Tag("positive") | | TestNG | @Test(groups = {"..."}) | @Test(groups = {"positive"}) | | pytest | @pytest.mark.<name> | @pytest.mark.positive | | RSpec | metadata after it | it "...", :positive do | | Pester | -Tag '...' | It '...' -Tag 'positive' | | Kotest | @Tags(...) | @Tags(Positive) | | Swift Testing | @Tag(.<name>) | @Test(.tags(.positive)) | | Catch2 | [tag] in name | TEST_CASE("...", "[positive]") | | doctest | * doctest::test_suite("...") decorator | TEST_CASE("..." *doctest::test_suite("positive")) |
Record which tests already have tags to avoid duplication.
Step 3: Classify each test method
Build one canonical inventory containing each discovered test exactly once. Record the test identifier, behavioral classification, and traits in that inventory; use the same rows for source edits, per-test reporting, totals, and distribution counts. Do not hand-count a separate denominator. Before publishing, reconcile the reported total with the number of inventory rows and verify that every row contributes to each displayed trait count.
For each test method without traits, analyze:
- Method name -- names containing
Invalid,Fail,Error,Throw,Reject,BadInput,Null,None,Nil,Negative,raises_,_throws_,_returns_errorsuggestnegative - Assertion type --
Assert.ThrowsException/Assert.Throws/Should().Throw()/pytest.raises/expect(fn).toThrow/assertThrows/assert.Error(t, err)/expect { ... }.to raise_error/#[should_panic]/XCTAssertThrowsError/Should -Throw/EXPECT_THROWsuggestnegative - Input values --
null/None/nil/undefined,"",0,-1,int.MaxValue/sys.maxsize/Number.MAX_SAFE_INTEGER/math.MaxInt64/i32::MAX, empty collections suggestboundary - Setup complexity -- minimal setup with basic assertions suggests
smoke; external dependencies (file/db/net/env) suggestintegration - Comments and names -- references to issue numbers or "regression" / "bug" / "fix for #..." suggest
regression - Timing assertions --
Stopwatch,BenchmarkDotNet, elapsed-time checks; pytest-benchmark fixtures; benchmark.js; JMH@Benchmark;go test -bench; criterion.rs; XCTMetric; Google Benchmark; kotlinx-benchmark suggestperformance - Feature centrality -- tests on primary public API entry points or critical user workflows suggest
critical-path - Security patterns -- validates auth, checks permissions, sanitizes input, tests for injection, handles tokens/secrets suggest
security - Parallel/async constructs -- per-language concurrency primitives (see Trait Taxonomy table) suggest
concurrency - Fault injection -- simulates failures, tests retries, timeouts, or circuit breakers suggest
resilience - State mutation -- deletes external records, drops resources, modifies shared/global state suggest
destructive - Full-stack flow -- test spans entry point through data layer to final response, covering a complete user scenario suggest
end-to-end - Config/settings -- loads configuration, tests missing keys, validates options, checks environment variables suggest
configuration - Known instability -- test has skip / ignore annotations with comments about flakiness, or names contain "flaky" / "intermittent" suggest
flaky - Default -- if the test verifies a normal success path, tag
positive
When in doubt between positive and negative, read the assertion: if it asserts success -> positive; if it asserts failure -> negative.
Step 4: Apply trait attributes (or report only)
If the loaded language extension declares `auto-edit` for the framework, add the appropriate attribute to each test method. Place trait attributes adjacent to the existing test attribute. Examples:
MSTest:
[TestMethod]
[TestCategory("negative")]
[TestCategory("boundary")]
public void Parse_NullInput_ThrowsArgumentNullException() { ... }
xUnit:
[Fact]
[Trait("Category", "positive")]
[Trait("Category", "critical-path")]
public void CreateOrder_ValidItems_ReturnsConfirmation() { ... }
NUnit:
[Test]
[Category("regression")]
[Category("negative")]
public void Calculate_OverflowInput_ReturnsError() // Fix for #1234
{ ... }
pytest:
@pytest.mark.negative
@pytest.mark.boundary
def test_parse_none_input_raises_value_error():
...
JUnit 5:
@Test
@Tag("positive")
@Tag("critical-path")
void createOrder_validItems_returnsConfirmation() { ... }
TestNG:
@Test(groups = {"negative", "boundary"})
public void parse_nullInput_throwsIllegalArgumentException() { ... }
RSpec:
it "rejects null input", :negative, :boundary do
...
end
Pester:
It 'Rejects null input' -Tag 'negative','boundary' {
...
}
Kotest:
@Tags(Negative, Boundary)
class ParserSpec : StringSpec({
"rejects null input" { ... }
})
Swift Testing:
@Test(.tags(.negative, .boundary))
func parseNullInputThrows() throws { ... }
Catch2:
TEST_CASE("Parse null input throws", "[negative][boundary]") { ... }
If the loaded language extension declares `report-only` for the framework (Go standard testing, plain Jest/Vitest without convention, Rust without project-specific cfg, plain XCTest, plain GoogleTest, plain Mocha), do NOT modify source files. Instead emit a concise mapping from each test to its suggested tags. Recommend a project-wide convention only when the user asks how to persist or filter those tags; an analysis-only request should report and stop.
If the loaded language extension declares `convention-based` (e.g., Go //go:build integration, *_integration_test.go, GoogleTest INTEGRATION_* prefix), only emit canonical edits when the user has confirmed the project's convention. Otherwise treat as report-only.
Step 5: Generate trait summary
After tagging, produce a summary table. Include only traits with a non-zero count unless the user asks for the full taxonomy; zero-filled rows obscure the suite's actual shape. For a small report-only suite, keep the per-test mapping and non-zero distribution together rather than expanding into a dashboard.
Related skills
Write, run, or repair .NET tests that use MSTest.
Write, run, or repair .NET tests that use NUnit.