chore: add REST API tests

.gitattributes

@@ -0,0 +1 @@
+* text=auto

app_to_test/expenses.http

@@ -5,7 +5,7 @@ Content-Type: application/json
   "id": "{{$random.uuid}}",
   "amount": {{$random.integer}},
   "category":  "Shopping",
-  "date": "2023-08-10",
+  "date": "2023-08-10T00:00:00Z",
   "notes":  "Shopping spree"
 }
 

app_to_test/server/api/api.go

@@ -18,7 +18,15 @@ func addExpenseHandler(expenseRepo *ExpenseRepo) http.HandlerFunc {
 		var expense Expense
 		err := json.NewDecoder(r.Body).Decode(&expense)
 		if err != nil {
+			slog.With(slog.String("error", err.Error())).Warn("invalid request body")
 			w.WriteHeader(http.StatusBadRequest)
+			w.Write([]byte(`{"error": "invalid request body"}`))
+			return
+		}
+
+		if expense.Category == "" {
+			w.WriteHeader(http.StatusBadRequest)
+			w.Write([]byte(`{"error": "category is required"}`))
 			return
 		}
 

app_to_test/server/api/repo.go

@@ -23,7 +23,10 @@ func (r *ExpenseRepo) Add(expense Expense) error {
 }
 
 func (r *ExpenseRepo) All() ([]Expense, error) {
-	rows, err := r.db.Query("SELECT id, amount, category, date, notes FROM expenses")
+	rows, err := r.db.Query(`
+		SELECT id, amount, category, date, notes 
+		FROM expenses
+	`)
 	if err != nil {
 		return nil, err
 	}

test_repos/repo_test.go

@@ -3,16 +3,13 @@ package test_repos
 import (
 	"context"
 	"database/sql"
-	"fmt"
 	"testing"
 	"time"
 
 	"github.com/antosdaniel/go-presentation-beyond-unit-tests/app_to_test/server/api"
 	_ "github.com/jackc/pgx/v5/stdlib"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
-	tc "github.com/testcontainers/testcontainers-go/modules/compose"
-	"github.com/testcontainers/testcontainers-go/wait"
 )
 
 // This would usually live next to repo it is testing
@@ -21,7 +18,7 @@ func TestExpenseRepo_Add(t *testing.T) {
 	ctx, cancel := context.WithTimeout(context.Background(), 20*time.Second)
 	defer cancel()
 
-	db := startDB(t, ctx)
+	db := StartDB(t, ctx).DB
 	expenseRepo := api.NewExpenseRepo(db)
 
 	t.Run("successfully adds expense", func(t *testing.T) {
@@ -59,42 +56,14 @@ func TestExpenseRepo_Add(t *testing.T) {
 	})
 }
 
-// This should be reused by other repo tests. It is kept here for simplicity.
-
-func startDB(t *testing.T, ctx context.Context) *sql.DB {
-	t.Helper()
-
-	compose, err := tc.NewDockerCompose("./../docker-compose-db-only.yaml")
-	require.NoError(t, err, "docker compose setup")
-
-	t.Cleanup(func() {
-		compose.Down(context.Background(), tc.RemoveOrphans(true), tc.RemoveImagesLocal)
-	})
-
-	err = compose.WaitForService("migrate", wait.ForExit()).Up(ctx)
-	require.NoError(t, err, "docker compose up")
-
-	dbContainer, err := compose.ServiceContainer(ctx, "db")
-	require.NoError(t, err, "docker compose db container")
-
-	dbPort, err := dbContainer.MappedPort(ctx, "5432")
-	require.NoError(t, err, "docker compose db port")
-
-	dsn := fmt.Sprintf("postgres://postgres:secret123@localhost:%s/expense_tracker?sslmode=disable", dbPort.Port())
-	db, err := sql.Open("pgx", dsn)
-	require.NoError(t, err, "pgx open")
-	t.Cleanup(func() {
-		db.Close()
-	})
-
-	return db
-}
-
 // getAllExpenses Test helper for getting all expenses from the database.
 func getAllExpenses(t *testing.T, db *sql.DB) api.Expenses {
 	t.Helper()
 
-	row, err := db.Query("SELECT id, amount, category, date, notes FROM expenses")
+	row, err := db.Query(`
+		SELECT id, amount, category, date, notes 
+		FROM expenses
+	`)
 	if err != nil {
 		t.Fatalf("could not query expenses: %v", err)
 	}

test_repos/start_db.go

@@ -0,0 +1,49 @@
+package test_repos
+
+import (
+	"context"
+	"database/sql"
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	tc "github.com/testcontainers/testcontainers-go/modules/compose"
+	"github.com/testcontainers/testcontainers-go/wait"
+)
+
+type DBContainer struct {
+	DB  *sql.DB
+	DSN string
+}
+
+func StartDB(t *testing.T, ctx context.Context) DBContainer {
+	t.Helper()
+
+	compose, err := tc.NewDockerCompose("./../docker-compose-db-only.yaml")
+	require.NoError(t, err, "docker compose setup")
+
+	t.Cleanup(func() {
+		compose.Down(context.Background(), tc.RemoveOrphans(true), tc.RemoveImagesLocal)
+	})
+
+	err = compose.WaitForService("migrate", wait.ForExit()).Up(ctx)
+	require.NoError(t, err, "docker compose up")
+
+	dbContainer, err := compose.ServiceContainer(ctx, "db")
+	require.NoError(t, err, "docker compose db container")
+
+	dbPort, err := dbContainer.MappedPort(ctx, "5432")
+	require.NoError(t, err, "docker compose db port")
+
+	dsn := fmt.Sprintf("postgres://postgres:secret123@localhost:%s/expense_tracker?sslmode=disable", dbPort.Port())
+	db, err := sql.Open("pgx", dsn)
+	require.NoError(t, err, "pgx open")
+	t.Cleanup(func() {
+		db.Close()
+	})
+
+	return DBContainer{
+		DB:  db,
+		DSN: dsn,
+	}
+}

test_rest_api/api_test.go

@@ -0,0 +1,106 @@
+package test_rest_api
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"testing"
+	"time"
+
+	"github.com/antosdaniel/go-presentation-beyond-unit-tests/app_to_test/server/api"
+	"github.com/antosdaniel/go-presentation-beyond-unit-tests/test_repos"
+	_ "github.com/jackc/pgx/v5/stdlib"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestAPI(t *testing.T) {
+	ctx, cancel := context.WithTimeout(context.Background(), 20*time.Second)
+	defer cancel()
+
+	server := startServer(t, ctx)
+
+	t.Run("summarize expenses", func(t *testing.T) {
+		// Notice that if we moved this test after add expense test, this test would fail.
+		// Usually it's better to reset the database before each test.
+		response, responseBody := call(t, server, http.MethodGet, "/expenses/summarize", "")
+
+		assert.Equal(t, http.StatusOK, response.StatusCode, "status code")
+		expected := getExpectedResponse(t)
+		assert.JSONEq(t, expected, responseBody, "response body")
+	})
+	t.Run("add expense successfully", func(t *testing.T) {
+		response, _ := call(t, server, http.MethodPost, "/expenses/add", getRequest(t))
+
+		assert.Equal(t, http.StatusCreated, response.StatusCode, "status code")
+		// We should check if expense was added to the database here.
+	})
+	t.Run("add expense fails", func(t *testing.T) {
+		response, responseBody := call(t, server, http.MethodPost, "/expenses/add", getRequest(t))
+
+		assert.Equal(t, http.StatusBadRequest, response.StatusCode, "status code")
+		expected := getExpectedResponse(t)
+		assert.JSONEq(t, expected, responseBody, "response body")
+	})
+}
+
+func startServer(t *testing.T, ctx context.Context) *httptest.Server {
+	t.Helper()
+
+	dbContainer := test_repos.StartDB(t, ctx)
+	require.NoError(t, os.Setenv("DB_URL", dbContainer.DSN), "set DB_URL env var")
+
+	setup, err := api.NewSetup()
+	require.NoError(t, err, "new setup")
+
+	server := httptest.NewServer(setup.APIMux)
+	t.Cleanup(func() {
+		server.Close()
+	})
+
+	return server
+}
+
+func call(t *testing.T, server *httptest.Server, method, path, body string) (*http.Response, string) {
+	t.Helper()
+
+	var b io.Reader
+	if body != "" {
+		b = bytes.NewBuffer([]byte(body))
+	}
+	request, err := http.NewRequest(method, server.URL+path, b)
+	require.NoError(t, err, "new request")
+
+	response, err := server.Client().Do(request)
+	require.NoError(t, err, "do request")
+
+	responseBody, err := io.ReadAll(response.Body)
+	require.NoError(t, err, "read response body")
+
+	return response, string(responseBody)
+
+}
+
+func getRequest(t *testing.T) string {
+	t.Helper()
+
+	path := fmt.Sprintf("./testdata/%s/request.json", t.Name())
+	file, err := os.ReadFile(path)
+	require.NoError(t, err, "read file")
+
+	return string(file)
+}
+
+func getExpectedResponse(t *testing.T) string {
+	t.Helper()
+
+	path := fmt.Sprintf("./testdata/%s/response.json", t.Name())
+	file, err := os.ReadFile(path)
+	require.NoError(t, err, "read file")
+
+	return string(file)
+}

test_rest_api/testdata/TestAPI/add_expense_fails/request.json

@@ -0,0 +1,7 @@
+{
+  "id": "057854f2-ca02-4ee7-92b0-d029125575d8",
+  "amount": 2500,
+  "category": "",
+  "date": "2023-08-10T00:00:00Z",
+  "notes": "Shopping spree"
+}

test_rest_api/testdata/TestAPI/add_expense_fails/response.json

@@ -0,0 +1,3 @@
+{
+  "error": "category is required"
+}

test_rest_api/testdata/TestAPI/add_expense_successfully/request.json

@@ -0,0 +1,7 @@
+{
+  "id": "057854f2-ca02-4ee7-92b0-d029125575d8",
+  "amount": 2500,
+  "category": "Shopping",
+  "date": "2023-08-10T00:00:00Z",
+  "notes": "Shopping spree"
+}

test_rest_api/testdata/TestAPI/summarize_expenses/response.json

@@ -0,0 +1,32 @@
+[
+  {
+    "year": 2023,
+    "month": 6,
+    "category": "Dining",
+    "total_amount": 130
+  },
+  {
+    "year": 2023,
+    "month": 6,
+    "category": "Entertainment",
+    "total_amount": 55
+  },
+  {
+    "year": 2023,
+    "month": 6,
+    "category": "Groceries",
+    "total_amount": 285
+  },
+  {
+    "year": 2023,
+    "month": 6,
+    "category": "Shopping",
+    "total_amount": 120
+  },
+  {
+    "year": 2023,
+    "month": 6,
+    "category": "Transportation",
+    "total_amount": 60
+  }
+]