From 9cd21186b171597a3b0af4e6ccd4d96fedf398cb Mon Sep 17 00:00:00 2001
From: "Michael B. Gale" <mbg@github.com>
Date: Mon, 12 Oct 2026 16:56:51 +0100
Subject: [PATCH] Add test for new `generateFailedSarif` behaviour

---
 src/init-action-post-helper.test.ts | 45 +++++++++++++++++++++++++++++
 src/init-action-post-helper.ts      | 11 ++++++-
 2 files changed, 55 insertions(+), 1 deletion(-)

diff --git a/src/init-action-post-helper.test.ts b/src/init-action-post-helper.test.ts
index fd1f489f7..4291361c2 100644
--- a/src/init-action-post-helper.test.ts
+++ b/src/init-action-post-helper.test.ts
@@ -1,3 +1,6 @@
+import * as fs from "fs";
+import * as path from "path";
+
 import * as core from "@actions/core";
 import test, { ExecutionContext } from "ava";
 import * as sinon from "sinon";
@@ -8,6 +11,7 @@ import * as apiClient from "./api-client";
 import * as codeql from "./codeql";
 import * as configUtils from "./config-utils";
 import * as debugArtifacts from "./debug-artifacts";
+import { getTempDiagnosticPath } from "./diagnostics";
 import { EnvVar } from "./environment";
 import { Feature } from "./feature-flags";
 import * as initActionPostHelper from "./init-action-post-helper";
@@ -35,6 +39,47 @@ const NUM_BYTES_PER_GIB = 1024 * 1024 * 1024;
 
 setupTests(test);
 
+test.serial("generateFailedSarif picks up unwritten diagnostics", async (t) =>
+  util.withTmpDir(async (tmpDir) => {
+    const logger = new RecordingLogger();
+
+    const tempDiagDir = getTempDiagnosticPath(tmpDir);
+    fs.mkdirSync(tempDiagDir);
+
+    const codeqlObject = await codeql.getCodeQLForTesting();
+    const diagnosticsExport = sinon
+      .stub(codeqlObject, "diagnosticsExport")
+      .resolves();
+
+    sinon.stub(codeql, "getCodeQL").resolves(codeqlObject);
+
+    const sarifFile = path.join(tmpDir, "failed.sarif");
+    const result = await initActionPostHelper.generateFailedSarif(
+      logger,
+      createFeatures([]),
+      createTestConfig({
+        tempDir: tmpDir,
+        // Explicitly undefined to ensure we get the "no database" path.
+        dbLocation: undefined,
+      }),
+      "category",
+      "",
+      sarifFile,
+    );
+
+    t.truthy(result);
+    t.is(diagnosticsExport.callCount, 1);
+    t.true(
+      diagnosticsExport.calledOnceWith(
+        sarifFile,
+        "category",
+        sinon.match.any,
+        tempDiagDir,
+      ),
+    );
+  }),
+);
+
 test.serial("init-post action with debug mode off", async (t) => {
   return await util.withTmpDir(async (tmpDir) => {
     setupActionsVars(tmpDir, tmpDir);
diff --git a/src/init-action-post-helper.ts b/src/init-action-post-helper.ts
index 9bae34654..873c0afc8 100644
--- a/src/init-action-post-helper.ts
+++ b/src/init-action-post-helper.ts
@@ -169,7 +169,16 @@ async function prepareFailedSarif(
   }
 }
 
-async function generateFailedSarif(
+/**
+ * Generates a SARIF file for a failed run, i.e. an analysis where no SARIF was produced as a result of the analysis.
+ *
+ * Not intended to be called directly, other than by `prepareFailedSarif`.
+ *
+ * @param category The analysis category to include in the SARIF.
+ * @param checkoutPath The path where the repository was checked out at.
+ * @param sarifFile The SARIF file to produce.
+ */
+export async function generateFailedSarif(
   logger: Logger,
   features: FeatureEnablement,
   config: ActionConfig<"codeQLCmd" | "tempDir">,