Add SQLCipher _key DSN support

sqlite3_test.go

@@ -103,6 +103,29 @@ func TestOpen(t *testing.T) {
 	}
 }
 
+func TestSQLCipherKeyPragma(t *testing.T) {
+	rawKey := "x'0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef'"
+	tests := []struct {
+		key  string
+		want string
+	}{
+		{rawKey, "PRAGMA key = \"" + rawKey + "\";"},
+		{"pass'word; PRAGMA foreign_keys = OFF", "PRAGMA key = 'pass''word; PRAGMA foreign_keys = OFF';"},
+	}
+	for _, test := range tests {
+		got, err := sqlCipherKeyPragma(test.key)
+		if err != nil {
+			t.Fatalf("sqlCipherKeyPragma(%q): %v", test.key, err)
+		}
+		if got != test.want {
+			t.Errorf("sqlCipherKeyPragma(%q) = %q; want %q", test.key, got, test.want)
+		}
+	}
+	if _, err := sqlCipherKeyPragma("pass\x00word"); err == nil {
+		t.Error("sqlCipherKeyPragma accepted a key containing NUL")
+	}
+}
+
 func TestOpenWithVFS(t *testing.T) {
 	filename := t.Name() + ".sqlite"