diff --git a/packages/chronus/src/release-plan/assemble-release-plan.test.ts b/packages/chronus/src/release-plan/assemble-release-plan.test.ts
new file mode 100644
index 00000000..adf979de
--- /dev/null
+++ b/packages/chronus/src/release-plan/assemble-release-plan.test.ts
@@ -0,0 +1,99 @@
+import type { NewChangeset, VersionType } from "@changesets/types";
+import { describe, expect, it } from "vitest";
+import type { ChronusConfig } from "../config/types.js";
+import type { Workspace } from "../workspace-manager/types.js";
+import { assembleReleasePlan } from "./assemble-release-plan.js";
+
+describe("Assemble Release Plan", () => {
+  let idCounter = 0;
+  function makeChangeset(pkg: string, type: VersionType): NewChangeset {
+    const id = String(idCounter++);
+    return { id, summary: `Changeset ${id}`, releases: [{ name: pkg, type }] };
+  }
+  const workspace: Workspace = {
+    path: "/",
+    packages: [
+      { name: "pkg-a", manifest: {}, relativePath: "packages/pkg-a", version: "1.0.0" },
+      { name: "pkg-b", manifest: {}, relativePath: "packages/pkg-b", version: "1.0.0" },
+      { name: "pkg-c", manifest: {}, relativePath: "packages/pkg-c", version: "1.0.0" },
+    ],
+  };
+
+  const baseConfig: ChronusConfig = { baseBranch: "main" };
+
+  describe("bumps package independently", () => {
+    it("only packages with changeset ", () => {
+      const plan = assembleReleasePlan([makeChangeset("pkg-a", "minor")], workspace, baseConfig);
+      expect(plan.actions).toHaveLength(1);
+      expect(plan.actions[0]).toMatchObject({ packageName: "pkg-a", oldVersion: "1.0.0", newVersion: "1.1.0" });
+    });
+
+    describe("picks the heighest version type", () => {
+      it("major", () => {
+        const plan = assembleReleasePlan(
+          [makeChangeset("pkg-a", "patch"), makeChangeset("pkg-a", "minor"), makeChangeset("pkg-a", "major")],
+          workspace,
+          baseConfig,
+        );
+        expect(plan.actions).toHaveLength(1);
+        expect(plan.actions[0]).toMatchObject({ packageName: "pkg-a", oldVersion: "1.0.0", newVersion: "2.0.0" });
+      });
+      it("minor", () => {
+        const plan = assembleReleasePlan(
+          [makeChangeset("pkg-a", "patch"), makeChangeset("pkg-a", "minor")],
+          workspace,
+          baseConfig,
+        );
+        expect(plan.actions).toHaveLength(1);
+        expect(plan.actions[0]).toMatchObject({ packageName: "pkg-a", oldVersion: "1.0.0", newVersion: "1.1.0" });
+      });
+    });
+
+    it("each package with changeset gets bumped accordingly", () => {
+      const plan = assembleReleasePlan(
+        [makeChangeset("pkg-a", "minor"), makeChangeset("pkg-b", "patch")],
+        workspace,
+        baseConfig,
+      );
+      expect(plan.actions).toHaveLength(2);
+      expect(plan.actions[0]).toMatchObject({ packageName: "pkg-a", oldVersion: "1.0.0", newVersion: "1.1.0" });
+      expect(plan.actions[1]).toMatchObject({ packageName: "pkg-b", oldVersion: "1.0.0", newVersion: "1.0.1" });
+    });
+  });
+
+  describe("lockStepVersioning", () => {
+    const lockStepConfig: ChronusConfig = {
+      ...baseConfig,
+      versionPolicies: [{ name: "lockStep", type: "lockstep", step: "minor", packages: ["pkg-a", "pkg-b"] }],
+    };
+
+    it("bumps all packages in the lockstep if one changed", () => {
+      const plan = assembleReleasePlan([makeChangeset("pkg-a", "minor")], workspace, lockStepConfig);
+      expect(plan.actions).toHaveLength(2);
+      expect(plan.actions[0]).toMatchObject({ packageName: "pkg-a", oldVersion: "1.0.0", newVersion: "1.1.0" });
+      expect(plan.actions[1]).toMatchObject({ packageName: "pkg-b", oldVersion: "1.0.0", newVersion: "1.1.0" });
+    });
+
+    it("bumps all packages in the lockstep of the step regardless of what changesets says (higher)", () => {
+      const plan = assembleReleasePlan(
+        [makeChangeset("pkg-a", "minor"), makeChangeset("pkg-a", "major")],
+        workspace,
+        lockStepConfig,
+      );
+      expect(plan.actions).toHaveLength(2);
+      expect(plan.actions[0]).toMatchObject({ packageName: "pkg-a", oldVersion: "1.0.0", newVersion: "1.1.0" });
+      expect(plan.actions[1]).toMatchObject({ packageName: "pkg-b", oldVersion: "1.0.0", newVersion: "1.1.0" });
+    });
+
+    it("bumps all packages in the lockstep of the step regardless of what changesets says (lower)", () => {
+      const plan = assembleReleasePlan(
+        [makeChangeset("pkg-a", "patch"), makeChangeset("pkg-a", "patch")],
+        workspace,
+        lockStepConfig,
+      );
+      expect(plan.actions).toHaveLength(2);
+      expect(plan.actions[0]).toMatchObject({ packageName: "pkg-a", oldVersion: "1.0.0", newVersion: "1.1.0" });
+      expect(plan.actions[1]).toMatchObject({ packageName: "pkg-b", oldVersion: "1.0.0", newVersion: "1.1.0" });
+    });
+  });
+});