encore-go-testing — Claude Code skill: tests and install

---
name: encore-go-testing
description: Write or run automated tests for Encore Go code with `encore test` and the standard library `testing` package. Covers isolated per-test databases, calling handlers directly, and `*testing.T` patterns.
when_to_use: >-
  User wants to add/write/fix a test in Go, write a `*_test.go` file, test an endpoint or service, set up `encore test`, configure isolated test databases, write `t.Cleanup`/`t.Helper` for db cleanup, mock external dependencies, or assert on API request/response behaviour. Trigger phrases: "write a Go test", "add tests for", "go test", "encore test", "test the endpoint", "test the service", "integration test", "isolated database".
---

# Testing Encore Go Applications

## Instructions

Encore Go uses standard Go testing with `encore test`.

### Run Tests

```bash
# Run all tests with Encore (recommended)
encore test ./...

# Run tests for a specific package
encore test ./user/...

# Run with verbose output
encore test -v ./...
```

Using `encore test` instead of `go test` is recommended because it:
- Sets up test databases automatically
- Provides isolated infrastructure per test
- Handles service dependencies

### Test an API Endpoint

```go
// hello/hello_test.go
package hello

import (
    "context"
    "testing"
)

func TestHello(t *testing.T) {
    ctx := context.Background()
    
    resp, err := Hello(ctx)
    if err != nil {
        t.Fatalf("unexpected error: %v", err)
    }
    
    if resp.Message != "Hello, World!" {
        t.Errorf("expected 'Hello, World!', got '%s'", resp.Message)
    }
}
```

### Test with Request Parameters

```go
// user/user_test.go
package user

import (
    "context"
    "testing"
)

func TestGetUser(t *testing.T) {
    ctx := context.Background()
    
    user, err := GetUser(ctx, &GetUserParams{ID: "123"})
    if err != nil {
        t.Fatalf("unexpected error: %v", err)
    }
    
    if user.ID != "123" {
        t.Errorf("expected ID '123', got '%s'", user.ID)
    }
}
```

### Test Database Operations

Encore provides isolated test databases:

```go
// user/user_test.go
package user

import (
    "context"
    "testing"
    
    "encore.dev/storage/sqldb"
)

func TestCreateUser(t *testing.T) {
    ctx := context.Background()
    
    // Clean up
    _, _ = sqldb.Exec(ctx, db, "DELETE FROM users")
    
    // Create user
    created, err := CreateUser(ctx, &CreateUserParams{
        Email: "[email protected]",
        Name:  "Test User",
    })
    if err != nil {
        t.Fatalf("failed to create user: %v", err)
    }
    
    // Retrieve and verify
    retrieved, err := GetUser(ctx, &GetUserParams{ID: created.ID})
    if err != nil {
        t.Fatalf("failed to get user: %v", err)
    }
    
    if retrieved.Email != "[email protected]" {
        t.Errorf("expected email '[email protected]', got '%s'", retrieved.Email)
    }
}
```

### Test Service-to-Service Calls

```go
// order/order_test.go
package order

import (
    "context"
    "testing"
)

func TestCreateOrder(t *testing.T) {
    ctx := context.Background()
    
    // Service calls work normally in tests
    order, err := CreateOrder(ctx, &CreateOrderParams{
        UserID: "user-123",
        Items: []OrderItem{
            {ProductID: "prod-1", Quantity: 2},
        },
    })
    if err != nil {
        t.Fatalf("failed to create order: %v", err)
    }
    
    if order.Status != "pending" {
        t.Errorf("expected status 'pending', got '%s'", order.Status)
    }
}
```

### Test Error Cases

```go
package user

import (
    "context"
    "errors"
    "testing"
    
    "encore.dev/beta/errs"
)

func TestGetUser_NotFound(t *testing.T) {
    ctx := context.Background()
    
    _, err := GetUser(ctx, &GetUserParams{ID: "nonexistent"})
    if err == nil {
        t.Fatal("expected error, got nil")
    }
    
    // Check error code
    var e *errs.Error
    if errors.As(err, &e) {
        if e.Code != errs.NotFound {
            t.Errorf("expected NotFound, got %v", e.Code)
        }
    } else {
        t.Errorf("expected errs.Error, got %T", err)
    }
}
```

### Test Pub/Sub

```go
// notifications/notifications_test.go
package notifications

import (
    "context"
    "testing"
    
    "myapp/events"
)

func TestPublishOrderCreated(t *testing.T) {
    ctx := context.Background()
    
    msgID, err := events.OrderCreated.Publish(ctx, &events.OrderCreatedEvent{
        OrderID: "order-123",
        UserID:  "user-456",
        Total:   9999,
    })
    if err != nil {
        t.Fatalf("failed to publish: %v", err)
    }
    
    if msgID == "" {
        t.Error("expected message ID, got empty string")
    }
}
```

### Test Cron Jobs

Test the underlying function, not the cron schedule:

```go
// cleanup/cleanup_test.go
package cleanup

import (
    "context"
    "testing"
)

func TestCleanupExpiredSessions(t *testing.T) {
    ctx := context.Background()
    
    // Create some expired sessions first
    createExpiredSession(ctx)
    
    // Call the endpoint directly
    err := CleanupExpiredSessions(ctx)
    if err != nil {
        t.Fatalf("cleanup failed: %v", err)
    }
    
    // Verify cleanup happened
    count := countSessions(ctx)
    if count != 0 {
        t.Errorf("expected 0 sessions, got %d", count)
    }
}
```

### Table-Driven Tests

```go
func TestValidateEmail(t *testing.T) {
    tests := []struct {
        name    string
        email   string
        wantErr bool
    }{
        {"valid email", "[email protected]", false},
        {"missing @", "userexample.com", true},
        {"empty", "", true},
        {"valid with subdomain", "[email protected]", false},
    }
    
    for _, tt := range tests {
        t.Run(tt.name, func(t *testing.T) {
            err := validateEmail(tt.email)
            if (err != nil) != tt.wantErr {
                t.Errorf("validateEmail(%q) error = %v, wantErr %v", tt.email, err, tt.wantErr)
            }
        })
    }
}
```

### Test with Subtests

```go
func TestUserCRUD(t *testing.T) {
    ctx := context.Background()
    var userID string
    
    t.Run("create", func(t *testing.T) {
        user, err := CreateUser(ctx, &CreateUserParams{
            Email: "[email protected]",
            Name:  "Test",
        })
        if err != nil {
            t.Fatalf("create failed: %v", err)
        }
        userID = user.ID
    })
    
    t.Run("read", func(t *testing.T) {
        user, err := GetUser(ctx, &GetUserParams{ID: userID})
        if err != nil {
            t.Fatalf("read failed: %v", err)
        }
        if user.Email != "[email protected]" {
            t.Errorf("wrong email: %s", user.Email)
        }
    })
    
    t.Run("delete", func(t *testing.T) {
        err := DeleteUser(ctx, &DeleteUserParams{ID: userID})
        if err != nil {
            t.Fatalf("delete failed: %v", err)
        }
    })
}
```

### Test Database Isolation

Create isolated, fully-migrated test databases using `et.NewTestDatabase()`:

```go
import "encore.dev/et"

func TestWithFreshDatabase(t *testing.T) {
    // Creates a new database with all migrations applied
    testDB := et.NewTestDatabase(t, db)

    // Use testDB for queries - it's completely isolated
    _, err := testDB.Exec(ctx, "INSERT INTO users (email) VALUES ($1)", "[email protected]")
    if err != nil {
        t.Fatal(err)
    }
}
```

### Service Instance Isolation

By default, service structs are shared across tests for performance. Enable isolation when tests modify service state:

```go
import "encore.dev/et"

func TestWithServiceIsolation(t *testing.T) {
    // Enable service instance isolation for this test
    et.EnableServiceInstanceIsolation()

    // Now this test gets its own service struct instance
    // preventing state interference with other tests
}
```

### Test Tracing Dashboard

View test execution traces in the development dashboard at `http://localhost:9400` while tests run. This helps diagnose failures by showing:
- Request/response data
- Database queries
- Service-to-service calls
- Errors and stack traces

### Mocking Endpoints and Services

Mock endpoints or entire services for isolated unit testing:

```go
import "encore.dev/et"

func TestWithMockedEndpoint(t *testing.T) {
    // Mock a specific endpoint
    et.MockEndpoint(products.GetPrice, func(ctx context.Context, p *products.PriceParams) (*products.PriceResponse, error) {
        return &products.PriceResponse{Price: 100}, nil
    })

    // Mock an entire service
    et.MockService("products", &mockProductService{})
}
```

### Guidelines

- Use `encore test` to run tests with infrastructure setup
- Each test gets access to real infrastructure (databases, Pub/Sub)
- Test API endpoints by calling them directly as functions
- Service-to-service calls work normally in tests
- Use table-driven tests for testing multiple cases
- Use `et.NewTestDatabase()` for isolated database testing
- Use `et.EnableServiceInstanceIsolation()` when tests modify service state
- Don't mock Encore infrastructure - use the real thing
- Mock external dependencies (third-party APIs, email services, etc.)