Add a reporter that emits test-related Open Telemetry spans.

This commit introduces a variant of the Check reporter that records Open
Telemetry traces for package tests. At present it records a parent span
for each context/file and child spans for each test case.

Span attributes are drawn from the semantic conventions [0].

It also makes some effort to work out the package's GitHub URL so that
we can set VCS-related attributes.

Note that this uses the existing session API from the `otel` package to
allow parallel testing, but this API has known issues.

Basic unit tests are included.

[0]: https://opentelemetry.io/docs/specs/semconv/registry/attributes/test/

Signed-off-by: Aaron Jacobs <aaron.jacobs@posit.co>

Author: atheriel

DESCRIPTION

@@ -41,6 +41,8 @@ Suggests:
     curl (>= 0.9.5),
     diffviewer (>= 0.1.0),
     knitr,
+    otel (>= 0.0.0.9000),
+    otelsdk (>= 0.0.0.9000),
     rmarkdown,
     rstudioapi,
     S7,
@@ -57,3 +59,6 @@ Config/testthat/start-first: watcher, parallel*
 Encoding: UTF-8
 Roxygen: list(markdown = TRUE, r6 = FALSE)
 RoxygenNote: 7.3.2.9000
+Remotes:  
+    r-lib/otel,
+    r-lib/otelsdk

NAMESPACE

@@ -40,6 +40,7 @@ export(ListReporter)
 export(LocationReporter)
 export(MinimalReporter)
 export(MultiReporter)
+export(OpenTelemetryReporter)
 export(ParallelProgressReporter)
 export(ProgressReporter)
 export(RStudioReporter)

R/reporter-otel.R

@@ -0,0 +1,246 @@
+#' OpenTelemetry reporter: traces for test results
+#'
+#' A variant of the Check reporter that also emits OpenTelemetry traces for
+#' tests. Span attributes are drawn from [the semantic conventions for
+#' tests](https://opentelemetry.io/docs/specs/semconv/registry/attributes/test/).
+#'
+#' @export
+#' @family reporters
+OpenTelemetryReporter <- R6::R6Class(
+  "OpenTelemetryReporter",
+  inherit = CheckReporter,
+  public = list(
+    tracer = NULL,
+    sessions = NULL,
+    suite_spans = NULL,
+    test_spans = NULL,
+    current_file = NULL,
+
+    #' @param pkg A path to an R package, by default the one in the current
+    #'   directory.
+    #' @param tracer An \pkg{otel} tracer, or `NULL` to use the default tracer.
+    initialize = function(pkg = ".", tracer = NULL, ..., call = caller_env()) {
+      check_installed("otel", "for emitting Open Telemetry traces", call = call)
+      set_pkg_resource_attributes(pkg)
+      self$tracer <- tracer %||% otel::get_tracer("testthat")
+      self$sessions <- new_environment()
+      self$suite_spans <- new_environment()
+      self$test_spans <- new_environment()
+      super$initialize(...)
+    },
+
+    start_file = function(file) {
+      # Track the current file so we can set it as an attribute on spans.
+      self$current_file <- file.path("tests/testthat", file)
+      context_start_file(file)
+    },
+
+    end_file = function(file) {
+      self$current_file <- NULL
+    },
+
+    start_context = function(context) {
+      # In order to handle concurrency issues with parallel tests, we maintain
+      # an otel session for each context and switch in and out of it as needed.
+      session <- self$tracer$start_session()
+      env_poke(self$sessions, context, session)
+      on.exit(self$tracer$deactivate_session())
+
+      span <- self$tracer$start_span(
+        name = "test_suite",
+        attributes = compact(list(
+          "test.suite.name" = context,
+          "code.filepath" = self$current_file
+        )),
+        scope = NULL
+      )
+      env_poke(self$suite_spans, context, span)
+    },
+
+    end_context = function(context) {
+      span <- env_get(self$suite_spans, context)
+      span$end()
+      env_unbind(self$suite_spans, context)
+
+      # Clean up the session.
+      session <- env_get(self$sessions, context)
+      self$tracer$finish_session(session)
+      env_unbind(self$sessions, context)
+    },
+
+    start_test = function(context, test) {
+      if (is.null(context)) {
+        # It seems like this can happen when running tests with a filter.
+        context <- names(self$sessions)[1]
+      }
+
+      # Ensure we start test spans (and any spans started by functions within
+      # that test) in the context's session.
+      session <- env_get(self$sessions, context)
+      self$tracer$activate_session(session)
+
+      key <- paste(context, test, sep = "|")
+      parent <- env_get(self$suite_spans, context)
+      span <- self$tracer$start_span(
+        name = "test_case",
+        attributes = list("test.case.name" = test),
+        options = list(parent = parent),
+        scope = NULL
+      )
+      env_poke(self$test_spans, key, span)
+    },
+
+    end_test = function(context, test) {
+      # Deactivate the context's session before starting the next test (which
+      # might have a different one).
+      on.exit(self$tracer$deactivate_session())
+
+      context <- context %||% names(self$sessions)[1]
+      key <- paste(context, test, sep = "|")
+      span <- env_get(self$test_spans, key)
+      if (span$is_recording() && !span$status_set) {
+        # If the span's status hasn't been set, we assume the test passed.
+        span$set_status("ok")
+        span$set_attribute("test.case.result.status", "pass")
+      }
+      span$end()
+      env_unbind(self$test_spans, key)
+    },
+
+    add_result = function(context, test, result) {
+      if (expectation_broken(result) || expectation_skip(result)) {
+        context <- context %||% names(self$sessions)[1]
+        key <- paste(context, test, sep = "|")
+        span <- env_get(self$test_spans, key)
+        if (!span$is_recording()) {
+          return(super$add_result(context, test, result))
+        }
+
+        # Extract source references, if possible.
+        filename <- NULL
+        line <- NULL
+        column <- NULL
+        if (inherits(result$srcref, "srcref")) {
+          filename <- attr(result$srcref, "srcfile")$filename
+          line <- result$srcref[1]
+          column <- result$srcref[2]
+        }
+        attributes <- compact(list(
+          "code.filepath" = file.path("tests/testthat", filename),
+          "code.lineno" = line,
+          "code.column" = column
+        ))
+
+        if (expectation_broken(result)) {
+          # Record error or failure expectations as exceptions on the test span.
+          span$record_exception(result, attributes = attributes)
+          # Mark the span as having errored. This is also what
+          # pytest-opentelemetry does.
+          span$set_status("error")
+          span$set_attribute("test.case.result.status", "fail")
+        } else if (expectation_skip(result)) {
+          # Record a special "skipped" event for skip expectations.
+          span$add_event("test_skipped", attributes = attributes)
+          span$set_status("unset")
+          span$set_attribute("test.case.result.status", "skipped")
+        }
+      }
+      super$add_result(context, test, result)
+    }
+  )
+)
+
+set_pkg_resource_attributes <- function(pkg = ".") {
+  attributes <- get_pkg_resource_attributes(pkg)
+  if (is.null(attributes)) {
+    return()
+  }
+  set_resource_attributes(.attributes = attributes)
+}
+
+get_pkg_resource_attributes <- function(pkg = ".") {
+  # Try to detect when we are testing a package.
+  if (!env_var_is_true("NOT_CRAN")) {
+    return(NULL)
+  }
+  # Use what we know about the package to set some resource attributes.
+  desc <- pkgload::pkg_desc(pkg)
+  attributes <- list(
+    "service.name" = desc$get_field("Package"),
+    "service.version" = desc$get_version(),
+    "vcs.repository.url.full" = get_repo_url(),
+    "vcs.repository.ref.revision" = get_git_revision()
+  )
+  # Existing environment variables take precedence.
+  from_env <- get_resource_attributes()
+  utils::modifyList(attributes, from_env)
+}
+
+get_repo_url <- function(pkg = ".") {
+  # Default to using the Github Actions context, if available.
+  if (nchar(repo <- Sys.getenv("GITHUB_REPOSITORY")) != 0) {
+    return(paste0(Sys.getenv("GITHUB_SERVER_URL"), "/", repo))
+  }
+  # Otherwise check if the package has a GitHub URL in its DESCRIPTION file.
+  desc <- pkgload::pkg_desc(pkg)
+  github_urls <- startsWith(desc$get_urls(), "https://github.com")
+  if (any(github_urls)) {
+    return(desc$get_urls()[github_urls][1])
+  }
+  NULL
+}
+
+get_git_revision <- function() {
+  # Default to using the Github Actions context, if available.
+  if (nchar(revision <- Sys.getenv("GITHUB_SHA")) != 0) {
+    return(revision)
+  }
+  tryCatch(
+    system2(
+      "git",
+      c("rev-parse", "HEAD"),
+      stdout = TRUE,
+      stderr = TRUE
+    )[1],
+    error = function(e) NULL
+  )
+}
+
+get_resource_attributes <- function(
+  env = Sys.getenv("OTEL_RESOURCE_ATTRIBUTES")
+) {
+  if (nchar(env) == 0) {
+    return(list())
+  }
+  # Split the attributes by comma and then by equals sign.
+  attrs <- strsplit(env, ",", fixed = TRUE)[[1]]
+  split <- strsplit(attrs, "=", fixed = TRUE)
+  out <- structure(
+    vector("list", length(split)),
+    .Names = character(length(split))
+  )
+  for (i in seq_along(split)) {
+    x <- split[[i]]
+    if (length(x) != 2) {
+      cli::cli_abort(
+        "Invalid {.env OTEL_RESOURCE_ATTRIBUTES} format: {.str {env}}",
+        .internal = TRUE
+      )
+    }
+    out[[i]] <- x[2]
+    names(out)[i] <- x[1]
+  }
+  out
+}
+
+set_resource_attributes <- function(..., .attributes = list()) {
+  attrs <- utils::modifyList(list(...), .attributes)
+  # Special handling for service.name, which isn't picked up by the SDK unless
+  # it's set in the dedicated environment variable.
+  if (!is.null(attrs["service.name"])) {
+    Sys.setenv(OTEL_SERVICE_NAME = attrs[["service.name"]])
+  }
+  attrs <- vapply(attrs, format, character(1L))
+  formatted <- paste(names(attrs), attrs, sep = "=", collapse = ",")
+  Sys.setenv(OTEL_RESOURCE_ATTRIBUTES = formatted)
+}