add missing files and adjust .gitignore rules for testing move

4 files changed, 1346 insertions, 10 deletions

diff --git a/.gitignore b/.gitignore
index af6e0cfa9..9dd96d838 100644
--- a/.gitignore
+++ b/.gitignore
@@ -42,10 +42,10 @@ src/bank-lib/test_bank_api_with_fakebank_twisted
 src/bank-lib/test_bank_api_with_pybank_twisted
 src/lib/test_exchange_api
 
-src/lib/test_taler_exchange_httpd_home/.local/share/taler/exchange/live-keys/
-src/lib/test_taler_exchange_httpd_home/.local/share/taler/exchange/wirefees/
-src/lib/test_taler_exchange_httpd_home/.local/share/taler/auditor/
-src/lib/test_taler_exchange_httpd_home/.local/share/taler/auditors/
+src/testing/test_taler_exchange_httpd_home/.local/share/taler/exchange/live-keys/
+src/testing/test_taler_exchange_httpd_home/.local/share/taler/exchange/wirefees/
+src/testing/test_taler_exchange_httpd_home/.local/share/taler/auditor/
+src/testing/test_taler_exchange_httpd_home/.local/share/taler/auditors/
 
 src/testing/test_exchange_api_keys_cherry_picking_home/.local/share/taler/exchange/live-keys/
 src/testing/test_exchange_api_keys_cherry_picking_home/.local/share/taler/exchange/wirefees/
@@ -55,7 +55,7 @@ src/testing/test_exchange_api_home/.local/share/taler/exchange/live-keys/
 src/testing/test_exchange_api_home/.local/share/taler/exchange/wirefees/
 src/testing/test_exchange_api_home/.local/share/taler/auditor/
 src/testing/test_exchange_api_home/.local/share/taler/auditors/
-src/lib/auditor.in
+src/testing/auditor.in
 src/testing/test_exchange_api_twisted
 src/exchange/taler-exchange-aggregator
 src/exchange/test_taler_exchange_aggregator-postgres
@@ -109,7 +109,7 @@ doc/manual/manual.vr
 doc/prebuilt/*
 contrib/taler-exchange.tag
 doxygen-doc/
-src/lib/test_exchange_api_keys_cherry_picking
+src/testing/test_exchange_api_keys_cherry_picking
 src/auditor/taler-wire-auditor
 contrib/auditor-report.aux
 contrib/auditor-report.log
@@ -117,10 +117,10 @@ contrib/auditor-report.tex
 contrib/auditor-report.pdf
 src/bank-lib/taler-bank-transfer
 src/bank-lib/test_bank_api_twisted
-src/lib/test_exchange_api
-src/lib/test_auditor_api
-src/lib/test_exchange_api_overlapping_keys_bug
-src/lib/test_exchange_api_home/.local/share/taler/exchange/revocations/
+src/testing/test_exchange_api
+src/testing/test_auditor_api
+src/testing/test_exchange_api_overlapping_keys_bug
+src/testing/test_exchange_api_home/.local/share/taler/exchange/revocations/
 src/wire-plugins/test_wire_plugin_legacy_taler_bank
 uncrustify.cfg
 vgcore.*
diff --git a/src/include/taler_twister_testing_lib.h b/src/include/taler_twister_testing_lib.h
new file mode 100644
index 000000000..fb0c352df
--- /dev/null
+++ b/src/include/taler_twister_testing_lib.h
@@ -0,0 +1,156 @@
+/*
+  This file is part of TALER
+  (C) 2018 Taler Systems SA
+
+  TALER is free software; you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as
+  published by the Free Software Foundation; either version 3, or
+  (at your option) any later version.
+
+  TALER is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public
+  License along with TALER; see the file COPYING.  If not, see
+  <http://www.gnu.org/licenses/>
+*/
+
+/**
+ * @file include/taler_twister_testing_lib.h
+ * @brief API for using twister-dependant test commands.
+ * @author Christian Grothoff <christian@grothoff.org>
+ * @author Marcello Stanisci
+ */
+#ifndef TALER_TWISTER_TESTING_LIB_H
+#define TALER_TWISTER_TESTING_LIB_H
+
+#include <taler/taler_testing_lib.h>
+
+#define TWISTER_FAIL() \
+  do {GNUNET_break (0); return NULL; } while (0)
+
+/**
+ * Define a "hack response code" CMD.  This causes the next
+ * response code (from the service proxied by the twister) to
+ * be substituted with @a http_status.
+ *
+ * @param label command label
+ * @param config_filename configuration filename.
+ * @param http_status new response code to use
+ * @return the command
+ */
+struct TALER_TESTING_Command
+TALER_TESTING_cmd_hack_response_code (const char *label,
+                                      const char *config_filename,
+                                      unsigned int http_status);
+
+/**
+ * Create a "delete object" CMD.  This command deletes
+ * the JSON object pointed by @a path.
+ *
+ * @param label command label
+ * @param config_filename configuration filename.
+ * @param path object-like path notation to point the object
+ *        to delete.
+ * @return the command
+ */
+struct TALER_TESTING_Command
+TALER_TESTING_cmd_delete_object (const char *label,
+                                 const char *config_filename,
+                                 const char *path);
+
+/**
+ * Create a "modify object" CMD.  This command instructs
+ * the twister to modify the next object that is downloaded
+ * from the proxied service.
+ *
+ * @param label command label
+ * @param config_filename configuration filename.
+ * @param path object-like path notation to point the object
+ *        to modify.
+ * @param value value to put as the object's.
+ *
+ * @return the command
+ */
+struct TALER_TESTING_Command
+TALER_TESTING_cmd_modify_object_dl (const char *label,
+                                    const char *config_filename,
+                                    const char *path,
+                                    const char *value);
+
+/**
+ * Create a "modify object" CMD.  This command instructs
+ * the twister to modify the next object that will be uploaded
+ * to the proxied service.
+ *
+ * @param label command label
+ * @param config_filename configuration filename.
+ * @param path object-like path notation pointing the object
+ *        to modify.
+ * @param value value to put as the object's.
+ * @return the command
+ */
+struct TALER_TESTING_Command
+TALER_TESTING_cmd_modify_object_ul (const char *label,
+                                    const char *config_filename,
+                                    const char *path,
+                                    const char *value);
+
+
+/**
+ * Create a "malform response" CMD.  This command makes
+ * the next response randomly malformed (by truncating it).
+ *
+ * @param label command label
+ * @param config_filename configuration filename.
+ *
+ * @return the command
+ */
+struct TALER_TESTING_Command
+TALER_TESTING_cmd_malform_response (const char *label,
+                                    const char *config_filename);
+
+/**
+ * Create a "malform request" CMD.  This command makes the
+ * next request randomly malformed (by truncating it).
+ *
+ * @param label command label
+ * @param config_filename configuration filename.
+ * @return the command
+ */
+struct TALER_TESTING_Command
+TALER_TESTING_cmd_malform_request (const char *label,
+                                   const char *config_filename);
+
+/**
+ * Define a "flip object" command, for objects to upload.
+ *
+ * @param label command label
+ * @param config_filename configuration filename.
+ * @param path object-like path notation to point the object
+ *        to flip.
+ * @return the command
+ */
+struct TALER_TESTING_Command
+TALER_TESTING_cmd_flip_upload (const char *label,
+                               const char *config_filename,
+                               const char *path);
+
+
+/**
+ * Define a "flip object" command, for objects to download.
+ *
+ * @param label command label
+ * @param config_filename configuration filename.
+ * @param path object-like path notation to point the object
+ *        to flip.
+ * @return the command
+ */
+struct TALER_TESTING_Command
+TALER_TESTING_cmd_flip_download (const char *label,
+                                 const char *config_filename,
+                                 const char *path);
+
+#endif
diff --git a/src/testing/testing_api_cmd_twister_exec_client.c b/src/testing/testing_api_cmd_twister_exec_client.c
new file mode 100644
index 000000000..6350d1d58
--- /dev/null
+++ b/src/testing/testing_api_cmd_twister_exec_client.c
@@ -0,0 +1,1023 @@
+/*
+  This file is part of TALER
+  (C) 2018 Taler Systems SA
+
+  TALER is free software; you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as
+  published by the Free Software Foundation; either version 3, or
+  (at your option) any later version.
+
+  TALER is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public
+  License along with TALER; see the file COPYING.  If not, see
+  <http://www.gnu.org/licenses/>
+*/
+
+/**
+ * @file include/testing_api_cmd_exec_client.h
+ * @brief test commands aimed to call the CLI twister client
+ *        to drive its behaviour.
+ * @author Christian Grothoff <christian@grothoff.org>
+ * @author Marcello Stanisci
+ */
+
+#include "platform.h"
+#include <taler/taler_testing_lib.h>
+#include "taler_twister_testing_lib.h"
+
+
+/**
+ * State for a "modify object" CMD.
+ */
+struct ModifyObjectState
+{
+  /**
+   * Process handle for the twister CLI client.
+   */
+  struct GNUNET_OS_Process *proc;
+
+  /**
+   * Object-like notation to the object to delete.
+   */
+  const char *path;
+
+
+  /**
+   * Value to substitute to the original one.
+   */
+  const char *value;
+
+  /**
+   * Config file name to pass to the CLI client.
+   */
+  const char *config_filename;
+};
+
+
+/**
+ * State for a "flip object" CMD.
+ */
+struct FlipObjectState
+{
+  /**
+   * Process handle for the twister CLI client.
+   */
+  struct GNUNET_OS_Process *proc;
+
+  /**
+   * Object-like notation to the string-object to flip.
+   */
+  const char *path;
+
+  /**
+   * Config file name to pass to the CLI client.
+   */
+  const char *config_filename;
+};
+
+
+/**
+ * State for a "delete object" CMD.
+ */
+struct DeleteObjectState
+{
+  /**
+   * Process handle for the twister CLI client.
+   */
+  struct GNUNET_OS_Process *proc;
+
+  /**
+   * Object-like notation to the object to delete.
+   */
+  const char *path;
+
+  /**
+   * Config file name to pass to the CLI client.
+   */
+  const char *config_filename;
+};
+
+
+/**
+ * State for a "malform request" CMD.
+ */
+struct MalformRequestState
+{
+  /**
+   * Process handle for the twister CLI client.
+   */
+  struct GNUNET_OS_Process *proc;
+
+  /**
+   * Config file name to pass to the CLI client.
+   */
+  const char *config_filename;
+};
+
+
+/**
+ * State for a "malform response" CMD.
+ */
+struct MalformResponseState
+{
+  /**
+   * Process handle for the twister CLI client.
+   */
+  struct GNUNET_OS_Process *proc;
+
+  /**
+   * Config file name to pass to the CLI client.
+   */
+  const char *config_filename;
+};
+
+
+/**
+ * State for a "hack response code" CMD.
+ */
+struct HackResponseCodeState
+{
+  /**
+   * Process handle for the twister CLI client.
+   */
+  struct GNUNET_OS_Process *proc;
+
+  /**
+   * HTTP status code to substitute to the original one.
+   */
+  unsigned int http_status;
+
+  /**
+   * Config file name to pass to the CLI client.
+   */
+  const char *config_filename;
+};
+
+
+/**
+ * Free the state from a "hack response code" CMD, and
+ * possibly kill its process if it did not terminate yet.
+ *
+ * @param cls closure.
+ * @param cmd the command being cleaned up.
+ */
+static void
+hack_response_code_cleanup
+  (void *cls,
+  const struct TALER_TESTING_Command *cmd)
+{
+  struct HackResponseCodeState *hrcs = cls;
+
+  if (NULL != hrcs->proc)
+  {
+    GNUNET_break (0 == GNUNET_OS_process_kill (hrcs->proc,
+                                               SIGKILL));
+    GNUNET_OS_process_wait (hrcs->proc);
+    GNUNET_OS_process_destroy (hrcs->proc);
+    hrcs->proc = NULL;
+  }
+  GNUNET_free (hrcs);
+}
+
+
+/**
+ * Offer data internal to a "hack response code" CMD,
+ * to other commands.
+ *
+ * @param cls closure
+ * @param ret[out] result (could be anything)
+ * @param trait name of the trait
+ * @param index index number of the object to offer.
+ * @return #GNUNET_OK on success
+ */
+static int
+hack_response_code_traits (void *cls,
+                           const void **ret,
+                           const char *trait,
+                           unsigned int index)
+{
+
+  struct HackResponseCodeState *hrcs = cls;
+  struct TALER_TESTING_Trait traits[] = {
+    TALER_TESTING_make_trait_process (0, &hrcs->proc),
+    TALER_TESTING_trait_end ()
+  };
+
+  return TALER_TESTING_get_trait (traits,
+                                  ret,
+                                  trait,
+                                  index);
+}
+
+
+/**
+ * Run a "hack response code" CMD.
+ *
+ * @param cls closure.
+ * @param cmd the command being run.
+ * @param is the interpreter state.
+ */
+static void
+hack_response_code_run (void *cls,
+                        const struct TALER_TESTING_Command *cmd,
+                        struct TALER_TESTING_Interpreter *is)
+{
+  struct HackResponseCodeState *hrcs = cls;
+  char *http_status;
+
+  GNUNET_asprintf (&http_status, "%u",
+                   hrcs->http_status);
+
+  hrcs->proc = GNUNET_OS_start_process
+                 (GNUNET_NO,
+                 GNUNET_OS_INHERIT_STD_ALL,
+                 NULL, NULL, NULL,
+                 "taler-twister",
+                 "taler-twister",
+                 "-c", hrcs->config_filename,
+                 "--responsecode", http_status,
+                 NULL);
+  if (NULL == hrcs->proc)
+  {
+    GNUNET_break (0);
+    TALER_TESTING_interpreter_fail (is);
+    return;
+  }
+  TALER_TESTING_wait_for_sigchld (is);
+  GNUNET_free (http_status);
+}
+
+
+/**
+ * Define a "hack response code" CMD.  This causes the next
+ * response code (from the service proxied by the twister) to
+ * be substituted with @a http_status.
+ *
+ * @param label command label
+ * @param config_filename configuration filename.
+ * @param http_status new response code to use
+ * @return the command
+ */
+struct TALER_TESTING_Command
+TALER_TESTING_cmd_hack_response_code (const char *label,
+                                      const char *config_filename,
+                                      unsigned int http_status)
+{
+  struct HackResponseCodeState *hrcs;
+
+  hrcs = GNUNET_new (struct HackResponseCodeState);
+  hrcs->http_status = http_status;
+  hrcs->config_filename = config_filename;
+
+  struct TALER_TESTING_Command cmd = {
+    .label = label,
+    .run = &hack_response_code_run,
+    .cleanup = &hack_response_code_cleanup,
+    .traits = &hack_response_code_traits,
+    .cls = hrcs
+  };
+
+  return cmd;
+}
+
+
+/**
+ * Free the state from a "delete object" CMD, and
+ * possibly kill its process if it did not terminate yet.
+ *
+ * @param cls closure.
+ * @param cmd the command being cleaned up.
+ */
+static void
+delete_object_cleanup
+  (void *cls,
+  const struct TALER_TESTING_Command *cmd)
+{
+  struct DeleteObjectState *dos = cls;
+
+  if (NULL != dos->proc)
+  {
+    GNUNET_break (0 == GNUNET_OS_process_kill (dos->proc,
+                                               SIGKILL));
+    GNUNET_OS_process_wait (dos->proc);
+    GNUNET_OS_process_destroy (dos->proc);
+    dos->proc = NULL;
+  }
+  GNUNET_free (dos);
+}
+
+
+/**
+ * Offer data internal to a "delete object" CMD,
+ * to other commands.
+ *
+ * @param cls closure
+ * @param ret[out] result (could be anything)
+ * @param trait name of the trait
+ * @param index index number of the object to offer.
+ * @return #GNUNET_OK on success
+ */
+static int
+delete_object_traits (void *cls,
+                      const void **ret,
+                      const char *trait,
+                      unsigned int index)
+{
+
+  struct DeleteObjectState *dos = cls;
+  struct TALER_TESTING_Trait traits[] = {
+    TALER_TESTING_make_trait_process (0, &dos->proc),
+    TALER_TESTING_trait_end ()
+  };
+
+  return TALER_TESTING_get_trait (traits,
+                                  ret,
+                                  trait,
+                                  index);
+}
+
+
+/**
+ * Run a "delete object" CMD.
+ *
+ * @param cls closure.
+ * @param cmd the command being run.
+ * @param is the interpreter state.
+ */
+static void
+delete_object_run (void *cls,
+                   const struct TALER_TESTING_Command *cmd,
+                   struct TALER_TESTING_Interpreter *is)
+{
+  struct DeleteObjectState *dos = cls;
+
+  dos->proc = GNUNET_OS_start_process (GNUNET_NO,
+                                       GNUNET_OS_INHERIT_STD_ALL,
+                                       NULL, NULL, NULL,
+                                       "taler-twister",
+                                       "taler-twister",
+                                       "-c", dos->config_filename,
+                                       "--deleteobject", dos->path,
+                                       NULL);
+  if (NULL == dos->proc)
+  {
+    GNUNET_break (0);
+    TALER_TESTING_interpreter_fail (is);
+    return;
+  }
+  TALER_TESTING_wait_for_sigchld (is);
+}
+
+
+/**
+ * Free the state from a "modify object" CMD, and
+ * possibly kill its process if it did not terminate yet.
+ *
+ * @param cls closure.
+ * @param cmd the command being cleaned up.
+ */
+static void
+modify_object_cleanup
+  (void *cls,
+  const struct TALER_TESTING_Command *cmd)
+{
+  struct ModifyObjectState *mos = cls;
+
+  if (NULL != mos->proc)
+  {
+    GNUNET_break (0 == GNUNET_OS_process_kill (mos->proc,
+                                               SIGKILL));
+    GNUNET_OS_process_wait (mos->proc);
+    GNUNET_OS_process_destroy (mos->proc);
+    mos->proc = NULL;
+  }
+  GNUNET_free (mos);
+}
+
+
+/**
+ * Offer data internal to a "modify object" CMD,
+ * to other commands.
+ *
+ * @param cls closure
+ * @param ret[out] result (could be anything)
+ * @param trait name of the trait
+ * @param index index number of the object to offer.
+ * @return #GNUNET_OK on success
+ */
+static int
+modify_object_traits (void *cls,
+                      const void **ret,
+                      const char *trait,
+                      unsigned int index)
+{
+
+  struct ModifyObjectState *mos = cls;
+  struct TALER_TESTING_Trait traits[] = {
+    TALER_TESTING_make_trait_process (0, &mos->proc),
+    TALER_TESTING_trait_end ()
+  };
+
+  return TALER_TESTING_get_trait (traits,
+                                  ret,
+                                  trait,
+                                  index);
+}
+
+
+/**
+ * Run a "modify object" CMD.  The "download fashion" of it.
+ *
+ * @param cls closure.
+ * @param cmd the command being run.
+ * @param is the interpreter state.
+ */
+static void
+modify_object_dl_run (void *cls,
+                      const struct TALER_TESTING_Command *cmd,
+                      struct TALER_TESTING_Interpreter *is)
+{
+  struct ModifyObjectState *mos = cls;
+
+  mos->proc = GNUNET_OS_start_process (GNUNET_NO,
+                                       GNUNET_OS_INHERIT_STD_ALL,
+                                       NULL, NULL, NULL,
+                                       "taler-twister",
+                                       "taler-twister",
+                                       "-c", mos->config_filename,
+                                       "-m", mos->path,
+                                       "--value", mos->value,
+                                       NULL);
+  if (NULL == mos->proc)
+  {
+    GNUNET_break (0);
+    TALER_TESTING_interpreter_fail (is);
+    return;
+  }
+  TALER_TESTING_wait_for_sigchld (is);
+}
+
+
+/**
+ * Run a "modify object" CMD, the "upload fashion" of it.
+ *
+ * @param cls closure.
+ * @param cmd the command being run.
+ * @param is the interpreter state.
+ */
+static void
+modify_object_ul_run (void *cls,
+                      const struct TALER_TESTING_Command *cmd,
+                      struct TALER_TESTING_Interpreter *is)
+{
+  struct ModifyObjectState *mos = cls;
+
+  mos->proc = GNUNET_OS_start_process (GNUNET_NO,
+                                       GNUNET_OS_INHERIT_STD_ALL,
+                                       NULL, NULL, NULL,
+                                       "taler-twister",
+                                       "taler-twister",
+                                       "-c", mos->config_filename,
+                                       "-X", mos->path,
+                                       "--value", mos->value,
+                                       NULL);
+  if (NULL == mos->proc)
+  {
+    GNUNET_break (0);
+    TALER_TESTING_interpreter_fail (is);
+    return;
+  }
+  TALER_TESTING_wait_for_sigchld (is);
+}
+
+
+/**
+ * Create a "delete object" CMD.  This command deletes
+ * the JSON object pointed by @a path.
+ *
+ * @param label command label
+ * @param config_filename configuration filename.
+ * @param path object-like path notation to point the object
+ *        to delete.
+ * @return the command
+ */
+struct TALER_TESTING_Command
+TALER_TESTING_cmd_delete_object (const char *label,
+                                 const char *config_filename,
+                                 const char *path)
+{
+  struct DeleteObjectState *dos;
+
+  dos = GNUNET_new (struct DeleteObjectState);
+  dos->path = path;
+  dos->config_filename = config_filename;
+
+  struct TALER_TESTING_Command cmd = {
+    .label = label,
+    .run = &delete_object_run,
+    .cleanup = &delete_object_cleanup,
+    .traits = &delete_object_traits,
+    .cls = dos
+  };
+
+  return cmd;
+}
+
+
+/**
+ * Free the state from a "flip object" CMD, and
+ * possibly kill its process if it did not terminate yet.
+ *
+ * @param cls closure.
+ * @param cmd the command being cleaned up.
+ */
+static void
+flip_object_cleanup
+  (void *cls,
+  const struct TALER_TESTING_Command *cmd)
+{
+  struct FlipObjectState *fos = cls;
+
+  if (NULL != fos->proc)
+  {
+    GNUNET_break (0 == GNUNET_OS_process_kill (fos->proc,
+                                               SIGKILL));
+    GNUNET_OS_process_wait (fos->proc);
+    GNUNET_OS_process_destroy (fos->proc);
+    fos->proc = NULL;
+  }
+  GNUNET_free (fos);
+}
+
+
+/**
+ * Offer data internal to a "flip object" CMD,
+ * to other commands.
+ *
+ * @param cls closure
+ * @param ret[out] result (could be anything)
+ * @param trait name of the trait
+ * @param index index number of the object to offer.
+ * @return #GNUNET_OK on success
+ */
+static int
+flip_object_traits (void *cls,
+                    const void **ret,
+                    const char *trait,
+                    unsigned int index)
+{
+
+  struct FlipObjectState *fos = cls;
+  struct TALER_TESTING_Trait traits[] = {
+    TALER_TESTING_make_trait_process (0, &fos->proc),
+    TALER_TESTING_trait_end ()
+  };
+
+  return TALER_TESTING_get_trait (traits,
+                                  ret,
+                                  trait,
+                                  index);
+}
+
+
+/**
+ * Run a "flip object" CMD, the upload fashion of it.
+ *
+ * @param cls closure.
+ * @param cmd the command being run.
+ * @param is the interpreter state.
+ */
+static void
+flip_upload_run (void *cls,
+                 const struct TALER_TESTING_Command *cmd,
+                 struct TALER_TESTING_Interpreter *is)
+{
+  struct FlipObjectState *fos = cls;
+
+  fos->proc = GNUNET_OS_start_process (GNUNET_NO,
+                                       GNUNET_OS_INHERIT_STD_ALL,
+                                       NULL, NULL, NULL,
+                                       "taler-twister",
+                                       "taler-twister",
+                                       "-c", fos->config_filename,
+                                       "--flip-ul", fos->path,
+                                       NULL);
+  if (NULL == fos->proc)
+  {
+    GNUNET_break (0);
+    TALER_TESTING_interpreter_fail (is);
+    return;
+  }
+  TALER_TESTING_wait_for_sigchld (is);
+}
+
+
+/**
+ * Run a "flip object" CMD, the download fashion of it.
+ *
+ * @param cls closure.
+ * @param cmd the command being run.
+ * @param is the interpreter state.
+ */
+static void
+flip_download_run (void *cls,
+                   const struct TALER_TESTING_Command *cmd,
+                   struct TALER_TESTING_Interpreter *is)
+{
+  struct FlipObjectState *fos = cls;
+
+  fos->proc = GNUNET_OS_start_process (GNUNET_NO,
+                                       GNUNET_OS_INHERIT_STD_ALL,
+                                       NULL, NULL, NULL,
+                                       "taler-twister",
+                                       "taler-twister",
+                                       "-c", fos->config_filename,
+                                       "--flip-dl", fos->path,
+                                       NULL);
+  if (NULL == fos->proc)
+  {
+    GNUNET_break (0);
+    TALER_TESTING_interpreter_fail (is);
+    return;
+  }
+  TALER_TESTING_wait_for_sigchld (is);
+}
+
+
+/**
+ * Define a "flip object" command, for objects to upload.
+ *
+ * @param label command label
+ * @param config_filename configuration filename.
+ * @param path object-like path notation to point the object
+ *        to flip.
+ * @return the command
+ */
+struct TALER_TESTING_Command
+TALER_TESTING_cmd_flip_upload (const char *label,
+                               const char *config_filename,
+                               const char *path)
+{
+  struct FlipObjectState *dos;
+
+  dos = GNUNET_new (struct FlipObjectState);
+  dos->path = path;
+  dos->config_filename = config_filename;
+
+  struct TALER_TESTING_Command cmd = {
+    .label = label,
+    .run = &flip_upload_run,
+    .cleanup = &flip_object_cleanup,
+    .traits = &flip_object_traits,
+    .cls = dos
+  };
+
+  return cmd;
+}
+
+
+/**
+ * Define a "flip object" command, for objects to download.
+ *
+ * @param label command label
+ * @param config_filename configuration filename.
+ * @param path object-like path notation to point the object
+ *        to flip.
+ * @return the command
+ */
+struct TALER_TESTING_Command
+TALER_TESTING_cmd_flip_download (const char *label,
+                                 const char *config_filename,
+                                 const char *path)
+{
+  struct FlipObjectState *dos;
+
+  dos = GNUNET_new (struct FlipObjectState);
+  dos->path = path;
+  dos->config_filename = config_filename;
+
+  struct TALER_TESTING_Command cmd = {
+    .label = label,
+    .run = &flip_download_run,
+    .cleanup = &flip_object_cleanup,
+    .traits = &flip_object_traits,
+    .cls = dos
+  };
+
+  return cmd;
+}
+
+
+/**
+ * Free the state from a "malform request" CMD, and
+ * possibly kill its process if it did not terminate yet.
+ *
+ * @param cls closure.
+ * @param cmd the command being cleaned up.
+ */
+static void
+malform_request_cleanup (void *cls,
+                         const struct TALER_TESTING_Command *cmd)
+{
+  struct MalformRequestState *mrs = cls;
+
+  if (NULL != mrs->proc)
+  {
+    GNUNET_break (0 == GNUNET_OS_process_kill (mrs->proc,
+                                               SIGKILL));
+    GNUNET_OS_process_wait (mrs->proc);
+    GNUNET_OS_process_destroy (mrs->proc);
+    mrs->proc = NULL;
+  }
+  GNUNET_free (mrs);
+}
+
+
+/**
+ * Offer data internal to a "malform request" CMD,
+ * to other commands.
+ *
+ * @param cls closure
+ * @param ret[out] result (could be anything)
+ * @param trait name of the trait
+ * @param index index number of the object to offer.
+ * @return #GNUNET_OK on success
+ */
+static int
+malform_request_traits (void *cls,
+                        const void **ret,
+                        const char *trait,
+                        unsigned int index)
+{
+  struct MalformRequestState *mrs = cls;
+  struct TALER_TESTING_Trait traits[] = {
+    TALER_TESTING_make_trait_process (0, &mrs->proc),
+    TALER_TESTING_trait_end ()
+  };
+
+  return TALER_TESTING_get_trait (traits,
+                                  ret,
+                                  trait,
+                                  index);
+}
+
+
+/**
+ * Run a "malform request" CMD.
+ *
+ * @param cls closure.
+ * @param cmd the command being run.
+ * @param is the interpreter state.
+ */
+static void
+malform_request_run (void *cls,
+                     const struct TALER_TESTING_Command *cmd,
+                     struct TALER_TESTING_Interpreter *is)
+{
+  struct MalformRequestState *mrs = cls;
+
+  mrs->proc = GNUNET_OS_start_process (GNUNET_NO,
+                                       GNUNET_OS_INHERIT_STD_ALL,
+                                       NULL, NULL, NULL,
+                                       "taler-twister",
+                                       "taler-twister",
+                                       "-c", mrs->config_filename,
+                                       "--malformupload",
+                                       NULL);
+  if (NULL == mrs->proc)
+  {
+    GNUNET_break (0);
+    TALER_TESTING_interpreter_fail (is);
+    return;
+  }
+  TALER_TESTING_wait_for_sigchld (is);
+}
+
+
+/**
+ * Free the state from a "malform response" CMD, and
+ * possibly kill its process if it did not terminate yet.
+ *
+ * @param cls closure.
+ * @param cmd the command being cleaned up.
+ */
+static void
+malform_response_cleanup
+  (void *cls,
+  const struct TALER_TESTING_Command *cmd)
+{
+  struct MalformResponseState *mrs = cls;
+
+  if (NULL != mrs->proc)
+  {
+    GNUNET_break (0 == GNUNET_OS_process_kill (mrs->proc,
+                                               SIGKILL));
+    GNUNET_OS_process_wait (mrs->proc);
+    GNUNET_OS_process_destroy (mrs->proc);
+    mrs->proc = NULL;
+  }
+  GNUNET_free (mrs);
+}
+
+
+/**
+ * Offer data internal to a "malform response" CMD,
+ * to other commands.
+ *
+ * @param cls closure
+ * @param ret[out] result (could be anything)
+ * @param trait name of the trait
+ * @param index index number of the object to offer.
+ * @return #GNUNET_OK on success
+ */
+static int
+malform_response_traits (void *cls,
+                         const void **ret,
+                         const char *trait,
+                         unsigned int index)
+{
+  struct MalformResponseState *mrs = cls;
+  struct TALER_TESTING_Trait traits[] = {
+    TALER_TESTING_make_trait_process (0, &mrs->proc),
+    TALER_TESTING_trait_end ()
+  };
+
+  return TALER_TESTING_get_trait (traits,
+                                  ret,
+                                  trait,
+                                  index);
+}
+
+
+/**
+ * Run a "malform response" CMD.
+ *
+ * @param cls closure.
+ * @param cmd the command being run.
+ * @param is the interpreter state.
+ */
+static void
+malform_response_run (void *cls,
+                      const struct TALER_TESTING_Command *cmd,
+                      struct TALER_TESTING_Interpreter *is)
+{
+  struct MalformResponseState *mrs = cls;
+
+  mrs->proc = GNUNET_OS_start_process (GNUNET_NO,
+                                       GNUNET_OS_INHERIT_STD_ALL,
+                                       NULL, NULL, NULL,
+                                       "taler-twister",
+                                       "taler-twister",
+                                       "-c", mrs->config_filename,
+                                       "--malform",
+                                       NULL);
+  if (NULL == mrs->proc)
+  {
+    GNUNET_break (0);
+    TALER_TESTING_interpreter_fail (is);
+    return;
+  }
+  TALER_TESTING_wait_for_sigchld (is);
+}
+
+
+/**
+ * Create a "malform request" CMD.  This command makes the
+ * next request randomly malformed (by truncating it).
+ *
+ * @param label command label
+ * @param config_filename configuration filename.
+ * @return the command
+ */
+struct TALER_TESTING_Command
+TALER_TESTING_cmd_malform_request (const char *label,
+                                   const char *config_filename)
+{
+  struct MalformRequestState *mrs;
+
+  mrs = GNUNET_new (struct MalformRequestState);
+  mrs->config_filename = config_filename;
+
+  struct TALER_TESTING_Command cmd = {
+    .label = label,
+    .run = &malform_request_run,
+    .cleanup = &malform_request_cleanup,
+    .traits = &malform_request_traits,
+    .cls = mrs
+  };
+
+  return cmd;
+}
+
+
+/**
+ * Create a "malform response" CMD.  This command makes
+ * the next response randomly malformed (by truncating it).
+ *
+ * @param label command label
+ * @param config_filename configuration filename.
+ *
+ * @return the command
+ */
+struct TALER_TESTING_Command
+TALER_TESTING_cmd_malform_response (const char *label,
+                                    const char *config_filename)
+{
+  struct MalformResponseState *mrs;
+
+  mrs = GNUNET_new (struct MalformResponseState);
+  mrs->config_filename = config_filename;
+
+  struct TALER_TESTING_Command cmd = {
+    .label = label,
+    .run = &malform_response_run,
+    .cleanup = &malform_response_cleanup,
+    .traits = &malform_response_traits,
+    .cls = mrs
+  };
+
+  return cmd;
+
+}
+
+
+/**
+ * Create a "modify object" CMD.  This command instructs
+ * the twister to modify the next object that is downloaded
+ * from the proxied service.
+ *
+ * @param label command label
+ * @param config_filename configuration filename.
+ * @param path object-like path notation to point the object
+ *        to modify.
+ * @param value value to put as the object's.
+ *
+ * @return the command
+ */
+struct TALER_TESTING_Command
+TALER_TESTING_cmd_modify_object_dl (const char *label,
+                                    const char *config_filename,
+                                    const char *path,
+                                    const char *value)
+{
+  struct ModifyObjectState *mos;
+
+  mos = GNUNET_new (struct ModifyObjectState);
+  mos->path = path;
+  mos->value = value;
+  mos->config_filename = config_filename;
+
+  struct TALER_TESTING_Command cmd = {
+    .label = label,
+    .run = &modify_object_dl_run,
+    .cleanup = &modify_object_cleanup,
+    .traits = &modify_object_traits,
+    .cls = mos
+  };
+
+  return cmd;
+}
+
+
+/**
+ * Create a "modify object" CMD.  This command instructs
+ * the twister to modify the next object that will be uploaded
+ * to the proxied service.
+ *
+ * @param label command label
+ * @param config_filename configuration filename.
+ * @param path object-like path notation pointing the object
+ *        to modify.
+ * @param value value to put as the object's.
+ * @return the command
+ */
+struct TALER_TESTING_Command
+TALER_TESTING_cmd_modify_object_ul (const char *label,
+                                    const char *config_filename,
+                                    const char *path,
+                                    const char *value)
+{
+  struct ModifyObjectState *mos;
+
+  mos = GNUNET_new (struct ModifyObjectState);
+  mos->path = path;
+  mos->value = value;
+  mos->config_filename = config_filename;
+
+  struct TALER_TESTING_Command cmd = {
+    .label = label,
+    .run = &modify_object_ul_run,
+    .cleanup = &modify_object_cleanup,
+    .traits = &modify_object_traits,
+    .cls = mos
+  };
+
+  return cmd;
+}
+
+
+/* end of testing_api_cmd_exec_client.c */
diff --git a/src/testing/testing_api_twister_helpers.c b/src/testing/testing_api_twister_helpers.c
new file mode 100644
index 000000000..6fab02c34
--- /dev/null
+++ b/src/testing/testing_api_twister_helpers.c
@@ -0,0 +1,157 @@
+/*
+  This file is part of TALER
+  Copyright (C) 2014-2018 Taler Systems SA
+
+  TALER is free software; you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as
+  published by the Free Software Foundation; either version 3, or
+  (at your option) any later version.
+
+  TALER is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public
+  License along with TALER; see the file COPYING.  If not, see
+  <http://www.gnu.org/licenses/>
+*/
+
+/**
+ * @file twister/testing_api_helpers.c
+ * @brief helper functions for test library.
+ * @author Christian Grothoff
+ * @author Marcello Stanisci
+ */
+
+#include "platform.h"
+#include <gnunet/gnunet_util_lib.h>
+#include "taler_twister_testing_lib.h"
+
+/**
+ * Prepare twister for execution; mainly checks whether the
+ * HTTP port is available and construct the base URL based on it.
+ *
+ * @param config_filename configuration file name.
+ * @return twister base URL, NULL upon errors.
+ */
+char *
+TALER_TWISTER_prepare_twister (const char *config_filename)
+{
+  struct GNUNET_CONFIGURATION_Handle *cfg;
+  unsigned long long port;
+  char *base_url;
+
+  cfg = GNUNET_CONFIGURATION_create ();
+
+  if (GNUNET_OK != GNUNET_CONFIGURATION_load
+        (cfg, config_filename))
+    TWISTER_FAIL ();
+
+  if (GNUNET_OK != GNUNET_CONFIGURATION_get_value_number
+        (cfg, "twister",
+        "HTTP_PORT", &port))
+  {
+    GNUNET_log_config_missing (GNUNET_ERROR_TYPE_ERROR,
+                               "twister",
+                               "HTTP_PORT");
+    GNUNET_CONFIGURATION_destroy (cfg);
+    TWISTER_FAIL ();
+  }
+
+  GNUNET_CONFIGURATION_destroy (cfg);
+
+  if (GNUNET_OK != GNUNET_NETWORK_test_port_free
+        (IPPROTO_TCP, (uint16_t) port))
+  {
+    fprintf (stderr,
+             "Required port %llu not available, skipping.\n",
+             port);
+    TWISTER_FAIL ();
+  }
+
+  GNUNET_assert (0 < GNUNET_asprintf
+                   (&base_url,
+                   "http://localhost:%llu/",
+                   port));
+
+  return base_url;
+}
+
+
+/**
+ * Run the twister service.
+ *
+ * @param config_filename configuration file name.
+ * @return twister process handle, NULL upon errors.
+ */
+struct GNUNET_OS_Process *
+TALER_TWISTER_run_twister (const char *config_filename)
+{
+  struct GNUNET_OS_Process *proc;
+  struct GNUNET_OS_Process *client_proc;
+  unsigned long code;
+  enum GNUNET_OS_ProcessStatusType type;
+
+  proc = GNUNET_OS_start_process (GNUNET_NO,
+                                  GNUNET_OS_INHERIT_STD_ALL,
+                                  NULL, NULL, NULL,
+                                  "taler-twister-service",
+                                  "taler-twister-service",
+                                  "-c", config_filename,
+                                  NULL);
+  if (NULL == proc)
+    TWISTER_FAIL ();
+
+  client_proc = GNUNET_OS_start_process (GNUNET_NO,
+                                         GNUNET_OS_INHERIT_STD_ALL,
+                                         NULL, NULL, NULL,
+                                         "taler-twister",
+                                         "taler-twister",
+                                         "-c", config_filename,
+                                         "-a", NULL);
+  if (NULL == client_proc)
+  {
+    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                "Could not start the taler-twister client\n");
+    GNUNET_OS_process_kill (proc, SIGTERM);
+    GNUNET_OS_process_wait (proc);
+    GNUNET_OS_process_destroy (proc);
+    TWISTER_FAIL ();
+  }
+
+
+  if (GNUNET_SYSERR == GNUNET_OS_process_wait_status
+        (client_proc, &type, &code))
+  {
+    GNUNET_OS_process_destroy (client_proc);
+    GNUNET_OS_process_kill (proc, SIGTERM);
+    GNUNET_OS_process_wait (proc);
+    GNUNET_OS_process_destroy (proc);
+    TWISTER_FAIL ();
+  }
+  if ( (type == GNUNET_OS_PROCESS_EXITED) &&
+       (0 != code) )
+  {
+    fprintf (stderr, "Failed to check twister works.\n");
+    GNUNET_OS_process_destroy (client_proc);
+    GNUNET_OS_process_kill (proc, SIGTERM);
+    GNUNET_OS_process_wait (proc);
+    GNUNET_OS_process_destroy (proc);
+    TWISTER_FAIL ();
+  }
+  if ( (type != GNUNET_OS_PROCESS_EXITED) ||
+       (0 != code) )
+  {
+    fprintf (stderr, "Unexpected error running"
+             " `taler-twister'!\n");
+    GNUNET_OS_process_destroy (client_proc);
+    GNUNET_OS_process_kill (proc, SIGTERM);
+    GNUNET_OS_process_wait (proc);
+    GNUNET_OS_process_destroy (proc);
+    TWISTER_FAIL ();
+  }
+  GNUNET_OS_process_destroy (client_proc);
+
+  return proc;
+}