feat(FN-3234): refactor test-changed script and add workflow tests

This merge refactors the test-changed script and adds new CLI tests (FN-3234), keeping automation on the full-suite path. It includes a new test file for the root test command, updates to the CI workflow, and documentation improvements.

Fusion-Task-Id: FN-3234

packages/cli/src/__tests__/ci-workflow.test.ts

@@ -103,11 +103,12 @@ describe("CI workflow (.github/workflows/ci.yml)", () => {
   });
 
   it("keeps contributing docs aligned with verification and slow-lane contracts", () => {
-    expect(contributingContent).toContain("pnpm test` must be runnable in a clean worktree without requiring a prior `pnpm build`.");
+    expect(contributingContent).toContain("pnpm test:full` must be runnable in a clean worktree without requiring a prior `pnpm build`.");
     expect(contributingContent).toContain("`pnpm verify:workspace` is the canonical pre-merge gate");
     expect(contributingContent).toContain("1. `pnpm lint`");
-    expect(contributingContent).toContain("2. `pnpm test`");
+    expect(contributingContent).toContain("2. `pnpm test:full`");
     expect(contributingContent).toContain("3. `pnpm build`");
+    expect(contributingContent).toContain("`pnpm test` now uses a changed-only entrypoint");
 
     expect(contributingContent).toContain("pnpm test:slow-cli");
     expect(contributingContent).toContain("test:pre-release");
@@ -154,6 +155,35 @@ describe("CI workflow (.github/workflows/ci.yml)", () => {
   });
 });
 
+describe("PR checks workflow (.github/workflows/pr-checks.yml)", () => {
+  let workflow: any;
+  let content: string;
+  let steps: any[];
+
+  beforeAll(() => {
+    const result = loadWorkflow("pr-checks.yml");
+    workflow = result.parsed;
+    content = result.content;
+    steps = workflow.jobs?.checks?.steps ?? [];
+  });
+
+  it("is valid YAML", () => {
+    expect(workflow).toBeDefined();
+    expect(typeof workflow).toBe("object");
+  });
+
+  it("runs on pull requests targeting main", () => {
+    expect(workflow.on?.pull_request?.branches).toContain("main");
+  });
+
+  it("runs explicit full-suite tests (not changed-only root test)", () => {
+    const testStep = steps.find((step: any) => step.name?.includes("Test"));
+    expect(testStep).toBeDefined();
+    expect(testStep.run).toBe("pnpm test:full");
+    expect(content).not.toContain("run: pnpm test\n");
+  });
+});
+
 describe("Version & Release workflow (.github/workflows/version.yml)", () => {
   let workflow: any;
   let content: string;

packages/cli/src/__tests__/package-config.test.ts

@@ -114,19 +114,18 @@ describe("Scoped @fusion/* packages publishing config", () => {
 describe("Workspace bootstrap script contract", () => {
   const rootPkg = loadRootPackageJson();
 
-  it("keeps root test self-sufficient (no implicit pre-build dependency)", () => {
-    const testScript = rootPkg.scripts?.test;
-    expect(testScript).toBeDefined();
-    expect(testScript).toContain("pnpm -r");
-    expect(testScript).not.toContain("pnpm build");
+  it("makes root test changed-only while keeping explicit full-suite command", () => {
+    expect(rootPkg.scripts?.test).toBe("node scripts/test-changed.mjs");
+    expect(rootPkg.scripts?.["test:full"]).toContain("pnpm -r --workspace-concurrency=2 test");
+    expect(rootPkg.scripts?.["test:full"]).not.toContain("pnpm build");
   });
 
-  it("defines verify:workspace in lint -> test -> build order", () => {
+  it("defines verify:workspace in lint -> test:full -> build order", () => {
     const verifyScript = rootPkg.scripts?.["verify:workspace"];
-    expect(verifyScript).toBe("pnpm lint && pnpm test && pnpm build");
+    expect(verifyScript).toBe("pnpm lint && pnpm test:full && pnpm build");
 
     const lintIdx = verifyScript.indexOf("pnpm lint");
-    const testIdx = verifyScript.indexOf("pnpm test");
+    const testIdx = verifyScript.indexOf("pnpm test:full");
     const buildIdx = verifyScript.indexOf("pnpm build");
 
     expect(lintIdx).toBeGreaterThanOrEqual(0);

packages/cli/src/__tests__/root-test-command.test.ts

@@ -0,0 +1,57 @@
+import { describe, expect, it } from "vitest";
+import {
+  decideExecutionPlan,
+  resolveAffectedPackages,
+  shouldForceFullSuite,
+} from "../../../../scripts/test-changed.mjs";
+
+describe("root test command changed-only planning", () => {
+  it("uses changed mode when package-only changes are detected", () => {
+    const packageMap = new Map([
+      ["core", "@fusion/core"],
+      ["engine", "@fusion/engine"],
+    ]);
+
+    const plan = decideExecutionPlan({
+      forceFullSuite: false,
+      comparisonBase: "abc123",
+      changedFiles: ["packages/core/src/store.ts", "packages/engine/src/index.ts"],
+      packageNameByDir: packageMap,
+    });
+
+    expect(plan).toEqual({ mode: "changed", packages: ["@fusion/core", "@fusion/engine"] });
+  });
+
+  it("falls back to full suite when shared test infra changes", () => {
+    const plan = decideExecutionPlan({
+      forceFullSuite: false,
+      comparisonBase: "abc123",
+      changedFiles: ["scripts/test-with-lock.mjs"],
+      packageNameByDir: new Map([["core", "@fusion/core"]]),
+    });
+
+    expect(plan).toEqual({ mode: "full", reason: "shared-infra-changed" });
+  });
+
+  it("falls back to full suite when comparison base cannot be resolved", () => {
+    const plan = decideExecutionPlan({
+      forceFullSuite: false,
+      comparisonBase: null,
+      changedFiles: null,
+      packageNameByDir: new Map(),
+    });
+
+    expect(plan).toEqual({ mode: "full", reason: "missing-comparison-base" });
+  });
+
+  it("treats unknown package directories as full-suite fallback", () => {
+    const resolved = resolveAffectedPackages(["packages/unknown/src/index.ts"], new Map());
+    expect(resolved).toBeNull();
+  });
+
+  it("marks root workflow/config changes as full-suite triggers", () => {
+    expect(shouldForceFullSuite([".github/workflows/ci.yml"])).toBe(true);
+    expect(shouldForceFullSuite(["package.json"])).toBe(true);
+    expect(shouldForceFullSuite(["packages/core/src/store.ts"])).toBe(false);
+  });
+});