Refactor testing to use Fakes and Dependency Injection

src/agent_engine_cli/dependencies.py

@@ -0,0 +1,19 @@
+"""Dependency injection for AgentEngineClient."""
+
+from agent_engine_cli.client import AgentEngineClient
+
+
+def get_client(project: str, location: str) -> AgentEngineClient:
+    """Create a new AgentEngineClient instance.
+
+    This function serves as a dependency injection point for the CLI.
+    Tests can patch this function to return a fake client.
+
+    Args:
+        project: Google Cloud project ID
+        location: Google Cloud region
+
+    Returns:
+        An instance of AgentEngineClient
+    """
+    return AgentEngineClient(project=project, location=location)

src/agent_engine_cli/main.py

@@ -1,5 +1,6 @@
 import asyncio
 import json
+from collections.abc import MutableMapping
 from typing import Annotated, Literal
 
 import typer
@@ -10,8 +11,8 @@
 
 from agent_engine_cli import __version__
 from agent_engine_cli.chat import run_chat
-from agent_engine_cli.client import AgentEngineClient
 from agent_engine_cli.config import ConfigurationError, resolve_project
+from agent_engine_cli.dependencies import get_client
 
 console = Console()
 
@@ -41,8 +42,8 @@ def list_agents(
         raise typer.Exit(code=1)
 
     try:
-        client = AgentEngineClient(project=project, location=location)
-        agents = client.list_agents()
+        client = get_client(project=project, location=location)
+        agents = list(client.list_agents())
 
         if not agents:
             console.print("No agents found.")
@@ -107,7 +108,7 @@ def get_agent(
         raise typer.Exit(code=1)
 
     try:
-        client = AgentEngineClient(project=project, location=location)
+        client = get_client(project=project, location=location)
         agent = client.get_agent(agent_id)
 
         # v1beta1 api_resource uses 'name' instead of 'resource_name'
@@ -247,7 +248,7 @@ def create_agent(
         raise typer.Exit(code=1)
 
     try:
-        client = AgentEngineClient(project=project, location=location)
+        client = get_client(project=project, location=location)
         console.print(f"Creating agent '{escape(display_name)}'...")
 
         agent = client.create_agent(
@@ -288,7 +289,7 @@ def delete_agent(
             raise typer.Exit()
 
     try:
-        client = AgentEngineClient(project=project, location=location)
+        client = get_client(project=project, location=location)
         client.delete_agent(agent_id, force=force)
         console.print(f"[red]Agent '{escape(agent_id)}' deleted.[/red]")
     except Exception as e:
@@ -315,7 +316,7 @@ def list_sessions(
         raise typer.Exit(code=1)
 
     try:
-        client = AgentEngineClient(project=project, location=location)
+        client = get_client(project=project, location=location)
         sessions = list(client.list_sessions(agent_id))
 
         if not sessions:
@@ -383,8 +384,12 @@ def list_sandboxes(
         raise typer.Exit(code=1)
 
     try:
-        client = AgentEngineClient(project=project, location=location)
-        sandboxes = client.list_sandboxes(agent_id)
+        client = get_client(project=project, location=location)
+        sandboxes = list(client.list_sandboxes(agent_id))
+
+        if not sandboxes:
+            console.print("No sandboxes found.")
+            return
 
         table = Table(title="Sandboxes")
         table.add_column("Sandbox ID", style="cyan")
@@ -393,9 +398,7 @@ def list_sandboxes(
         table.add_column("Created")
         table.add_column("Expires")
 
-        has_items = False
         for sandbox in sandboxes:
-            has_items = True
             # Extract sandbox ID from full resource name
             sandbox_name = getattr(sandbox, "name", "") or ""
             sandbox_id = sandbox_name.split("/")[-1] if sandbox_name else ""
@@ -430,10 +433,6 @@ def list_sandboxes(
                 expire_time,
             )
 
-        if not has_items:
-            console.print("No sandboxes found.")
-            return
-
         console.print(table)
     except Exception as e:
         console.print(f"[red]Error listing sandboxes: {e}[/red]")
@@ -459,8 +458,8 @@ def list_memories(
         raise typer.Exit(code=1)
 
     try:
-        client = AgentEngineClient(project=project, location=location)
-        memories = client.list_memories(agent_id)
+        client = get_client(project=project, location=location)
+        memories = list(client.list_memories(agent_id))
 
         if not memories:
             console.print("No memories found.")
@@ -484,7 +483,7 @@ def list_memories(
 
             # Format scope dict as key=value pairs
             scope_raw = getattr(memory, "scope", None)
-            if scope_raw and isinstance(scope_raw, dict):
+            if scope_raw and isinstance(scope_raw, (dict, MutableMapping)):
                 scope = ", ".join(f"{k}={v}" for k, v in scope_raw.items())
             else:
                 scope = ""

tests/fakes.py

@@ -0,0 +1,127 @@
+"""Fake implementations for testing."""
+
+from datetime import datetime
+from typing import Any, Iterator
+from dataclasses import dataclass
+from enum import Enum
+
+from google.cloud.aiplatform_v1beta1.types import ReasoningEngine, ReasoningEngineSpec, Session, Memory
+
+
+class SandboxState(str, Enum):
+    STATE_UNSPECIFIED = "STATE_UNSPECIFIED"
+    STATE_RUNNING = "STATE_RUNNING"
+    STATE_STOPPED = "STATE_STOPPED"
+
+
+@dataclass
+class Sandbox:
+    """Fake Sandbox since the real one is not easily importable."""
+    name: str
+    display_name: str
+    state: Any
+    create_time: datetime
+    expire_time: datetime
+
+
+@dataclass
+class CreateAgentCall:
+    """Records the arguments passed to create_agent."""
+    display_name: str
+    identity_type: str
+    service_account: str | None
+
+
+class FakeAgentEngineClient:
+    """Fake client for Agent Engine."""
+
+    def __init__(self, project: str, location: str):
+        self.project = project
+        self.location = location
+        self._agents: dict[str, ReasoningEngine] = {}
+        self._sessions: dict[str, list[Session]] = {}
+        self._sandboxes: dict[str, list[Sandbox]] = {}
+        self._memories: dict[str, list[Memory]] = {}
+        self.create_agent_calls: list[CreateAgentCall] = []
+
+    def _get_full_name(self, resource_type: str, resource_id: str) -> str:
+        return f"projects/{self.project}/locations/{self.location}/{resource_type}/{resource_id}"
+
+    def list_agents(self) -> Iterator[ReasoningEngine]:
+        return iter(self._agents.values())
+
+    def get_agent(self, agent_id: str) -> ReasoningEngine:
+        if "/" in agent_id:
+            name = agent_id
+        else:
+            name = self._get_full_name("reasoningEngines", agent_id)
+
+        if name in self._agents:
+            return self._agents[name]
+
+        for agent_name, agent in self._agents.items():
+            if agent_name.endswith(f"/{agent_id}"):
+                return agent
+
+        raise Exception(f"Agent {agent_id} not found")
+
+    def create_agent(
+        self,
+        display_name: str,
+        identity_type: str,
+        service_account: str | None = None,
+    ) -> ReasoningEngine:
+        self.create_agent_calls.append(
+            CreateAgentCall(display_name=display_name, identity_type=identity_type, service_account=service_account)
+        )
+
+        agent_id = f"agent-{len(self._agents) + 1}"
+        name = self._get_full_name("reasoningEngines", agent_id)
+
+        spec = ReasoningEngineSpec(agent_framework="langchain")
+        agent = ReasoningEngine(
+            name=name,
+            display_name=display_name,
+            spec=spec,
+            create_time=datetime.now(),
+            update_time=datetime.now(),
+        )
+
+        self._agents[name] = agent
+        return agent
+
+    def delete_agent(self, agent_id: str, force: bool = False) -> None:
+        if "/" in agent_id:
+            name = agent_id
+        else:
+            name = self._get_full_name("reasoningEngines", agent_id)
+
+        if name not in self._agents:
+            for agent_name in list(self._agents.keys()):
+                if agent_name.endswith(f"/{agent_id}"):
+                    name = agent_name
+                    break
+
+        if name in self._agents:
+            if not force:
+                if self._sessions.get(name) or self._memories.get(name) or self._sandboxes.get(name):
+                    raise Exception("Agent has resources, use force to delete")
+
+            del self._agents[name]
+            self._sessions.pop(name, None)
+            self._sandboxes.pop(name, None)
+            self._memories.pop(name, None)
+        else:
+            raise Exception(f"Agent {agent_id} not found")
+
+    def list_sessions(self, agent_id: str) -> Iterator[Session]:
+        agent = self.get_agent(agent_id)
+        return iter(self._sessions.get(agent.name, []))
+
+    def list_sandboxes(self, agent_id: str) -> Iterator[Sandbox]:
+        agent = self.get_agent(agent_id)
+        return iter(self._sandboxes.get(agent.name, []))
+
+    def list_memories(self, agent_id: str) -> Iterator[Memory]:
+        agent = self.get_agent(agent_id)
+        return iter(self._memories.get(agent.name, []))

tests/test_fix_attribute_error.py

@@ -4,8 +4,8 @@
 
 runner = CliRunner()
 
-@patch("agent_engine_cli.main.AgentEngineClient")
-def test_get_agent_with_none_class_methods(mock_client_class):
+@patch("agent_engine_cli.main.get_client")
+def test_get_agent_with_none_class_methods(mock_get_client):
     """Test get command when spec.class_methods is None (regression test)."""
 
     # Mock spec with class_methods=None
@@ -25,7 +25,7 @@ def test_get_agent_with_none_class_methods(mock_client_class):
 
     mock_client = MagicMock()
     mock_client.get_agent.return_value = mock_agent
-    mock_client_class.return_value = mock_client
+    mock_get_client.return_value = mock_client
 
     result = runner.invoke(
         app, ["get", "agent1", "--project", "test-project", "--location", "us-central1"]

tests/test_get_effective_identity.py

@@ -4,8 +4,8 @@
 
 runner = CliRunner()
 
-@patch("agent_engine_cli.main.AgentEngineClient")
-def test_get_agent_shows_effective_identity(mock_client_class):
+@patch("agent_engine_cli.main.get_client")
+def test_get_agent_shows_effective_identity(mock_get_client):
     """Test get command shows effective identity."""
     mock_spec = MagicMock()
     mock_spec.effective_identity = "service-account@test.iam.gserviceaccount.com"
@@ -27,7 +27,7 @@ def test_get_agent_shows_effective_identity(mock_client_class):
 
     mock_client = MagicMock()
     mock_client.get_agent.return_value = mock_agent
-    mock_client_class.return_value = mock_client
+    mock_get_client.return_value = mock_client
 
     result = runner.invoke(
         app, ["get", "agent1", "--project", "test-project", "--location", "us-central1"]