chore: import upstream snapshot with attribution

agent/loop_test.go

@@ -0,0 +1,71 @@
+package agent
+
+import (
+	"strings"
+	"testing"
+)
+
+// Repeating the same tool call with the same arguments is refused once it
+// exceeds LoopLimit, and the model is told to change approach.
+func TestLoopDetectionStopsRepeats(t *testing.T) {
+	a := newTestAgent(Name("looper"), LoopLimit(3))
+	h := a.toolHandler()
+
+	// First 3 identical calls are allowed (they fall through to RPC,
+	// which fails harmlessly — we only care they weren't refused as loops).
+	for i := 1; i <= 3; i++ {
+		content := toolContent(h, "demo_Svc_Do", map[string]any{"q": "x"})
+		if strings.Contains(content, "loop detected") {
+			t.Fatalf("call %d wrongly flagged as a loop", i)
+		}
+	}
+
+	// The 4th identical call is refused as a loop.
+	content := toolContent(h, "demo_Svc_Do", map[string]any{"q": "x"})
+	if !strings.Contains(content, "loop detected") {
+		t.Errorf("4th identical call should be refused as a loop; got %q", content)
+	}
+}
+
+// Different arguments are not a loop, even past the limit.
+func TestLoopDetectionAllowsDistinctCalls(t *testing.T) {
+	a := newTestAgent(Name("distinct"), LoopLimit(2))
+	h := a.toolHandler()
+
+	for i := 0; i < 5; i++ {
+		content := toolContent(h, "demo_Svc_Do", map[string]any{"q": i}) // distinct args each time
+		if strings.Contains(content, "loop detected") {
+			t.Fatalf("distinct call %d wrongly flagged as a loop", i)
+		}
+	}
+}
+
+// LoopLimit(0) disables detection.
+func TestLoopDetectionDisabled(t *testing.T) {
+	a := newTestAgent(Name("noloop"), LoopLimit(0))
+	h := a.toolHandler()
+	for i := 0; i < 6; i++ {
+		content := toolContent(h, "demo_Svc_Do", map[string]any{"q": "same"})
+		if strings.Contains(content, "loop detected") {
+			t.Fatalf("loop detection should be disabled with LoopLimit(0)")
+		}
+	}
+}
+
+// It defaults on (lenient) so repeated identical calls are caught without
+// any configuration.
+func TestLoopDetectionDefaultOn(t *testing.T) {
+	a := New(Name("d"), Provider("fake")).(*agentImpl)
+	a.setup()
+	if a.opts.LoopLimit <= 0 {
+		t.Fatalf("LoopLimit should default on, got %d", a.opts.LoopLimit)
+	}
+	h := a.toolHandler()
+	var lastContent string
+	for i := 0; i < a.opts.LoopLimit+1; i++ {
+		lastContent = toolContent(h, "demo_Svc_Do", map[string]any{})
+	}
+	if !strings.Contains(lastContent, "loop detected") {
+		t.Errorf("default loop detection should catch repeated calls; got %q", lastContent)
+	}
+}