Assignment 4: add unit, integration, and e2e tests; refactor for testability

internal/store/snippet_store.go

@@ -2,9 +2,11 @@ package store
 
 import (
 	"context"
+	"errors"
 	"sync"
 
 	"5803025015/w04/internal/models"
+
 	"github.com/google/uuid"
 	"github.com/jackc/pgx/v5"
 )
@@ -45,23 +47,28 @@ func (s *SnippetStore) GetByID(ctx context.Context, id string) (*models.Snippet,
 	query := `SELECT id, title, content, user_id FROM snippets WHERE id = $1`
 	err := s.conn.QueryRow(ctx, query, id).Scan(&sn.ID, &sn.Title, &sn.Content, &sn.UserID)
 	if err != nil {
+		if errors.Is(err, pgx.ErrNoRows) {
+			return nil, ErrNotFound
+		}
 		return nil, err
 	}
 	return &sn, nil
 }
 
-func (s *SnippetStore) GetAll(ctx context.Context) ([]*models.Snippet, error) {
+// ListByOwner returns only the snippets belonging to ownerID.
+// Return value is always non-nil (empty slice when none).
+func (s *SnippetStore) ListByOwner(ctx context.Context, ownerID string) ([]*models.Snippet, error) {
 	s.mu.Lock()
 	defer s.mu.Unlock()
 
-	query := `SELECT id, title, content, user_id FROM snippets`
-	rows, err := s.conn.Query(ctx, query)
+	query := `SELECT id, title, content, user_id FROM snippets WHERE user_id = $1`
+	rows, err := s.conn.Query(ctx, query, ownerID)
 	if err != nil {
 		return nil, err
 	}
 	defer rows.Close()
 
-	snippets := make([]*models.Snippet, 0)
+	snippets := make([]*models.Snippet, 0) // non-nil!
 	for rows.Next() {
 		var sn models.Snippet
 		if err := rows.Scan(&sn.ID, &sn.Title, &sn.Content, &sn.UserID); err != nil {
@@ -80,6 +87,12 @@ func (s *SnippetStore) Delete(ctx context.Context, id string) error {
 	defer s.mu.Unlock()
 
 	query := `DELETE FROM snippets WHERE id = $1`
-	_, err := s.conn.Exec(ctx, query, id)
-	return err
+	tag, err := s.conn.Exec(ctx, query, id)
+	if err != nil {
+		return err
+	}
+	if tag.RowsAffected() == 0 {
+		return ErrNotFound
+	}
+	return nil
 }