refactor: extract base exporter, add sentinel errors, document unused fields

internal/apperrors/errors.go

@@ -0,0 +1,28 @@
+// Package apperrors provides sentinel errors for the articulate-parser application.
+package apperrors
+
+import "errors"
+
+// Export errors.
+var (
+	// ErrUnsupportedFormat is returned when an unknown export format is requested.
+	ErrUnsupportedFormat = errors.New("unsupported export format")
+)
+
+// URI parsing errors.
+var (
+	// ErrInvalidURI is returned when a URI cannot be parsed.
+	ErrInvalidURI = errors.New("invalid URI")
+
+	// ErrInvalidDomain is returned when the URI domain is not an Articulate Rise domain.
+	ErrInvalidDomain = errors.New("invalid domain for Articulate Rise URI")
+
+	// ErrNoShareID is returned when a share ID cannot be extracted from the URI.
+	ErrNoShareID = errors.New("could not extract share ID from URI")
+)
+
+// Operation errors.
+var (
+	// ErrOperationCanceled is returned when an operation is canceled via context.
+	ErrOperationCanceled = errors.New("operation canceled")
+)

internal/apperrors/errors_test.go

@@ -0,0 +1,50 @@
+package apperrors
+
+import (
+	"errors"
+	"fmt"
+	"testing"
+)
+
+func TestSentinelErrors_Unwrap(t *testing.T) {
+	tests := []struct {
+		name     string
+		sentinel error
+		wrapped  error
+	}{
+		{"ErrUnsupportedFormat", ErrUnsupportedFormat, fmt.Errorf("%w: xyz", ErrUnsupportedFormat)},
+		{"ErrInvalidURI", ErrInvalidURI, fmt.Errorf("%w: bad", ErrInvalidURI)},
+		{"ErrInvalidDomain", ErrInvalidDomain, fmt.Errorf("%w: evil.com", ErrInvalidDomain)},
+		{"ErrNoShareID", ErrNoShareID, fmt.Errorf("%w: no match", ErrNoShareID)},
+		{"ErrOperationCanceled", ErrOperationCanceled, fmt.Errorf("%w: ctx done", ErrOperationCanceled)},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if !errors.Is(tt.wrapped, tt.sentinel) {
+				t.Errorf("errors.Is(%v, %v) = false, want true", tt.wrapped, tt.sentinel)
+			}
+		})
+	}
+}
+
+func TestSentinelErrors_Message(t *testing.T) {
+	tests := []struct {
+		err      error
+		expected string
+	}{
+		{ErrUnsupportedFormat, "unsupported export format"},
+		{ErrInvalidURI, "invalid URI"},
+		{ErrInvalidDomain, "invalid domain for Articulate Rise URI"},
+		{ErrNoShareID, "could not extract share ID from URI"},
+		{ErrOperationCanceled, "operation canceled"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.expected, func(t *testing.T) {
+			if tt.err.Error() != tt.expected {
+				t.Errorf("got %q, want %q", tt.err.Error(), tt.expected)
+			}
+		})
+	}
+}