fix(artifacts): exclude removed paths from unchanged counts (#569)

src/domain/artifactComparison.ts

@@ -403,7 +403,8 @@ const summarize = (
     unchanged: covered
       ? Math.max(
           0,
-          Math.min(left.occurrences.length, right.occurrences.length) -
+          left.occurrences.length -
+            counts.removed -
             counts.changed -
             counts.contradiction -
             counts.unknown,

tests/boundary/filesystem/artifactComparisonSummary.test.ts

@@ -0,0 +1,88 @@
+import { mkdir, writeFile } from "node:fs/promises";
+import { join } from "node:path";
+
+import { describe, expect, it } from "vitest";
+
+import { inventoryArtifact } from "../../../src/application/ArtifactInventory.js";
+import { compareArtifacts } from "../../../src/domain/artifactComparison.js";
+import { createEvidence } from "../../../src/domain/evidence.js";
+import { jsonValueSchema } from "../../../src/domain/jsonValue.js";
+import { createTestTempDirectory } from "../../fixtures/temporaryDirectory.js";
+
+const observe = async (path: string) => {
+  const inventory = await inventoryArtifact(path);
+  return createEvidence(
+    {
+      path,
+      sha256: inventory.manifest.root_sha256,
+      format: inventory.manifest.root_format,
+    },
+    { id: "rea-artifact-graph", name: "REA artifact graph", version: "1" },
+    {
+      operation: "inventory_artifact",
+      parameters: {},
+      result: jsonValueSchema.parse(inventory),
+      confidence: "observed",
+      authority: "shipped-artifact",
+    },
+  );
+};
+
+describe("artifact comparison summary", () => {
+  it.each([
+    { removed: 1, added: 1 },
+    { removed: 1, added: 2 },
+    { removed: 2, added: 1 },
+    { removed: 0, added: 1 },
+    { removed: 1, added: 0 },
+    { removed: 0, added: 0 },
+  ])(
+    "counts unchanged paths with $removed removals and $added additions",
+    async ({ removed, added }) => {
+      const root = await createTestTempDirectory("rea-artifact-summary-");
+      const leftPath = join(root, "left");
+      const rightPath = join(root, "right");
+      await Promise.all([mkdir(leftPath), mkdir(rightPath)]);
+      await Promise.all(
+        [leftPath, rightPath].flatMap((path) =>
+          ["same.txt", "duplicate.txt"].map((name) =>
+            writeFile(join(path, name), "unchanged content"),
+          ),
+        ),
+      );
+      await Promise.all([
+        ...Array.from({ length: removed }, (_, index) =>
+          writeFile(join(leftPath, `removed-${index}.txt`), "old content"),
+        ),
+        ...Array.from({ length: added }, (_, index) =>
+          writeFile(join(rightPath, `added-${index}.txt`), "new content"),
+        ),
+      ]);
+      const [left, right] = await Promise.all([
+        observe(leftPath),
+        observe(rightPath),
+      ]);
+      const comparison = compareArtifacts(left, right);
+      const changed = removed + added > 0 ? 1 : 0;
+
+      expect(comparison.summary).toEqual({
+        unchanged: 3 - changed,
+        added,
+        removed,
+        changed,
+        unknown: 0,
+        contradiction: 0,
+      });
+      expect(comparison.changes).toHaveLength(removed + added + changed);
+      expect(comparison.summary.unchanged + comparison.changes.length).toBe(
+        3 + removed + added,
+      );
+      expect(
+        comparison.changes.map(({ logical_path }) => logical_path),
+      ).not.toContain("same.txt");
+      expect(
+        comparison.changes.map(({ logical_path }) => logical_path),
+      ).not.toContain("duplicate.txt");
+    },
+  );
+});