Make diagnostics less dependent on global state

Add limited test coverage

src/diagnostics.test.ts

@@ -0,0 +1,111 @@
+import * as fs from "fs";
+import path from "path";
+
+import test, { type ExecutionContext } from "ava";
+
+import * as diagnostics from "./diagnostics";
+import { BuiltInLanguage } from "./languages";
+import {
+  checkExpectedLogMessages,
+  createTestConfig,
+  initAllState,
+  RecordingLogger,
+  setupTests,
+} from "./testing-utils";
+import { withTmpDir } from "./util";
+
+setupTests(test);
+
+const id = "codeql-action/test-diagnostic";
+const name = "Test title";
+
+test("makeDiagnostic - adds expected properties", (t) => {
+  const diagnostic = diagnostics.makeDiagnostic(id, name, {});
+
+  t.truthy(diagnostic.timestamp);
+  t.is(diagnostic.source.id, id);
+  t.is(diagnostic.source.name, name);
+});
+
+/**
+ * Diagnostic files that are written to disk don't have deterministic names.
+ * This function recursively finds all `.json` files at {@link rootPath},
+ * asserts that there is exactly one, and that it matches {@link expected}.
+ *
+ * @param rootPath The path to start searching from.
+ */
+function assertSingleDiagnosticIn(
+  t: ExecutionContext<unknown>,
+  rootPath: string,
+  expected: diagnostics.DiagnosticMessage,
+) {
+  // Find all `.json` files in `rootPath` and check that there is exactly one.
+  const filePaths = fs
+    .readdirSync(rootPath, {
+      recursive: true,
+      encoding: "utf-8",
+    })
+    .filter((p) => p.endsWith(".json"));
+
+  t.is(filePaths.length, 1);
+
+  // Check that the written diagnostic matches the one we added.
+  const contents = fs.readFileSync(
+    path.resolve(rootPath, filePaths[0]),
+    "utf-8",
+  );
+
+  const readDiagnostic = JSON.parse(contents) as diagnostics.DiagnosticMessage;
+  t.deepEqual(readDiagnostic, expected);
+}
+
+test("addDiagnostic writes temporary diagnostics and flushDiagnostics moves them to the database", async (t) =>
+  withTmpDir(async (tmpDir) => {
+    const logger = new RecordingLogger();
+
+    const tempDiagDir = path.resolve(tmpDir, "temp");
+    const testDbDir = path.resolve(tmpDir, "test", "database");
+    const diagnostic = diagnostics.makeDiagnostic(id, name, {});
+
+    // Write the diagnostic. The path provided for `dbLocation` doesn't exist,
+    // so the diagnostic will be written to a temporary location.
+    t.notThrows(() => {
+      diagnostics.addDiagnostic(
+        createTestConfig({ tempDir: tempDiagDir, dbLocation: testDbDir }),
+        BuiltInLanguage.actions,
+        diagnostic,
+        logger,
+      );
+    });
+
+    // Check that `tempDiagDir` was created.
+    t.true(fs.existsSync(tempDiagDir));
+
+    // Check that the diagnostic exists under `tempDiagDir`.
+    assertSingleDiagnosticIn(t, tempDiagDir, diagnostic);
+
+    // Flush the diagnostics. This will cause the diagnostic we wrote previously to
+    // be moved to a location under `dbLocation`.
+    t.notThrows(() => {
+      diagnostics.flushDiagnostics(
+        initAllState({ logger }),
+        createTestConfig({
+          tempDir: tempDiagDir,
+          dbLocation: testDbDir,
+        }),
+      );
+    });
+
+    // Check that `testDbDir` was created.
+    t.true(fs.existsSync(testDbDir));
+
+    // Check that the diagnostic exists under `testDbDir`.
+    assertSingleDiagnosticIn(t, testDbDir, diagnostic);
+
+    // Check that we logged that the database directory doesn't exist yet
+    // and that we moved one diagnostic.
+    checkExpectedLogMessages(t, logger.messages, [
+      `but the database at ${path.join(testDbDir, "actions")} does not exist yet`,
+      "Moving 1 diagnostic(s) to their respective databases.",
+    ]);
+  }));