test: add simple unit tests for backend and logging packages

internal/backend/characters_test.go

@@ -0,0 +1,90 @@
+package backend
+
+import (
+	"io/fs"
+	"os"
+	"testing"
+)
+
+func TestIsImage(t *testing.T) {
+	tests := []struct {
+		name     string
+		entry    fs.DirEntry
+		expected bool
+	}{
+		{
+			name:     "jpg file",
+			entry:    &mockDirEntry{name: "test.jpg", isDir: false},
+			expected: true,
+		},
+		{
+			name:     "jpeg file",
+			entry:    &mockDirEntry{name: "test.jpeg", isDir: false},
+			expected: true,
+		},
+		{
+			name:     "png file",
+			entry:    &mockDirEntry{name: "test.png", isDir: false},
+			expected: true,
+		},
+		{
+			name:     "directory",
+			entry:    &mockDirEntry{name: "test", isDir: true},
+			expected: false,
+		},
+		{
+			name:     "txt file",
+			entry:    &mockDirEntry{name: "test.txt", isDir: false},
+			expected: false,
+		},
+		{
+			name:     "mp3 file",
+			entry:    &mockDirEntry{name: "test.mp3", isDir: false},
+			expected: false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := isImage(tt.entry)
+			if result != tt.expected {
+				t.Errorf("isImage() = %v, want %v", result, tt.expected)
+			}
+		})
+	}
+}
+
+type mockDirEntry struct {
+	name  string
+	isDir bool
+}
+
+func (m *mockDirEntry) Name() string       { return m.name }
+func (m *mockDirEntry) IsDir() bool         { return m.isDir }
+func (m *mockDirEntry) Type() fs.FileMode   { return 0 }
+func (m *mockDirEntry) Info() (fs.FileInfo, error) { return nil, nil }
+func (m *mockDirEntry) Sys() interface{}    { return nil }
+
+func TestGetCharacter(t *testing.T) {
+	os.Setenv("CHARACTERS_PATH", "/test/path")
+	defer os.Unsetenv("CHARACTERS_PATH")
+
+	result := GetCharacter("test.jpg")
+	expected := "/test/path/test.jpg"
+
+	if result != expected {
+		t.Errorf("GetCharacter() = %v, want %v", result, expected)
+	}
+}
+
+func TestGetCharacterWithTrailingSlash(t *testing.T) {
+	os.Setenv("CHARACTERS_PATH", "/test/path/")
+	defer os.Unsetenv("CHARACTERS_PATH")
+
+	result := GetCharacter("test.jpg")
+	expected := "/test/path/test.jpg"
+
+	if result != expected {
+		t.Errorf("GetCharacter() = %v, want %v", result, expected)
+	}
+}