test: add update version and checksum tests

internal/update/apply_test.go

@@ -0,0 +1,43 @@
+package update
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestParseChecksums(t *testing.T) {
+	checksums := `ABCDEF0123  godeez_1.0.0_darwin_arm64
+deadbeef  *godeez_1.0.0_linux_amd64
+malformed-line
+one two three
+cafebabe  godeez_1.0.0_windows_amd64.exe
+`
+
+	tests := []struct {
+		name  string
+		asset string
+		want  string
+	}{
+		{"plain name lowercased", "godeez_1.0.0_darwin_arm64", "abcdef0123"},
+		{"star-prefixed name", "godeez_1.0.0_linux_amd64", "deadbeef"},
+		{"windows asset", "godeez_1.0.0_windows_amd64.exe", "cafebabe"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := parseChecksums(strings.NewReader(checksums), tt.asset)
+			if err != nil {
+				t.Fatalf("parseChecksums: %v", err)
+			}
+			if got != tt.want {
+				t.Errorf("parseChecksums() = %q, want %q", got, tt.want)
+			}
+		})
+	}
+}
+
+func TestParseChecksumsMissing(t *testing.T) {
+	if _, err := parseChecksums(strings.NewReader("abc  other_asset\n"), "godeez_1.0.0_darwin_arm64"); err == nil {
+		t.Error("expected error for missing asset name")
+	}
+}