test(core): cover CappedTextBuffer and ToolCallIdAllocator (#9)

2026-07-22 22:06:58 +08:00
parent 1425b2fb5f
commit 7e0525af9f
2 changed files with 133 additions and 0 deletions
@@ -0,0 +1,62 @@
+/**
+ * CappedTextBuffer unit tests: capacity drop keeps the tail, the omitted tally accumulates,
+ * drain() prefixes the drop marker and clears the buffer, and isEmpty tracks both text and tally.
+ */
+import { describe, expect, it } from "vitest";
+import { CappedTextBuffer } from "../src/environment/tools/background/index.js";
+
+describe("CappedTextBuffer", () => {
+  it("starts empty and drains to an empty string", () => {
+    const buf = new CappedTextBuffer(10, "earlier output");
+    expect(buf.isEmpty).toBe(true);
+    expect(buf.drain()).toBe("");
+  });
+
+  it("keeps content under capacity verbatim", () => {
+    const buf = new CappedTextBuffer(10, "earlier output");
+    buf.append("hello");
+    expect(buf.isEmpty).toBe(false);
+    expect(buf.drain()).toBe("hello");
+    expect(buf.isEmpty).toBe(true);
+  });
+
+  it("drops the oldest chars past capacity and keeps the tail", () => {
+    const buf = new CappedTextBuffer(5, "earlier output");
+    buf.append("abcdefg"); // 7 chars, cap 5 -> drop "ab", keep "cdefg"
+    expect(buf.drain()).toBe("[... 2 chars of earlier output dropped ...]\ncdefg");
+  });
+
+  it("handles a single append larger than the cap", () => {
+    const buf = new CappedTextBuffer(3, "earlier output");
+    buf.append("0123456789"); // drop 7, keep "789"
+    expect(buf.drain()).toBe("[... 7 chars of earlier output dropped ...]\n789");
+  });
+
+  it("accumulates the omitted tally across multiple over-cap appends", () => {
+    const buf = new CappedTextBuffer(4, "earlier output");
+    buf.append("aaaaaa"); // drop 2, keep "aaaa"
+    buf.append("bb"); // now "aaaabb" -> drop 2 more, keep "aabb"
+    expect(buf.drain()).toBe("[... 4 chars of earlier output dropped ...]\naabb");
+  });
+
+  it("clears text and tally after drain", () => {
+    const buf = new CappedTextBuffer(2, "earlier output");
+    buf.append("xyz"); // drop 1, keep "yz"
+    buf.drain();
+    expect(buf.isEmpty).toBe(true);
+    expect(buf.drain()).toBe("");
+  });
+
+  it("uses the drop label in the marker", () => {
+    const buf = new CappedTextBuffer(1, "earlier subagent output");
+    buf.append("ab"); // drop 1
+    expect(buf.drain()).toBe("[... 1 chars of earlier subagent output dropped ...]\nb");
+  });
+
+  it("stays non-empty when only dropped chars remain unread", () => {
+    const buf = new CappedTextBuffer(0, "earlier output");
+    buf.append("ab"); // cap 0 -> everything dropped, text empty but tally=2
+    expect(buf.isEmpty).toBe(false);
+    expect(buf.drain()).toBe("[... 2 chars of earlier output dropped ...]\n");
+  });
+});