subsys: shell: add dummy backend to simplify commands testing

Added dummy backend which can be enabled with Kconfig. By default it is
disabled because it needs the same amount of memory as other phisical
backends. It shall be use only for commands testing purposes.

Improved shell_execute_cmd function, now it clears command context
before new command will be executed.

Signed-off-by: Jakub Rzeszutko <jakub.rzeszutko@nordicsemi.no>

include/shell/shell.h

@@ -600,7 +600,9 @@ void shell_print_stream(const void *user_ctx, const char *data,
  * Note: This by no means makes any of the commands a stable interface, so
  * this function should only be used for debugging/diagnostic.
  *
- * @param[in] shell	Pointer to the shell instance.
+ * @param[in] shell	Pointer to the shell instance. It can be NULL when
+ *			the :option:`CONFIG_SHELL_BACKEND_DUMMY` option is
+ *			enabled.
  * @param[in] cmd	Command to be executed.
  *
  * @returns Result of the execution

include/shell/shell_dummy.h

@@ -0,0 +1,44 @@
+/*
+ * Copyright (c) 2018 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#ifndef SHELL_DUMMY_H__
+#define SHELL_DUMMY_H__
+
+#include <shell/shell.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+extern const struct shell_transport_api shell_dummy_transport_api;
+
+struct shell_dummy {
+	bool initialized;
+};
+
+#define SHELL_DUMMY_DEFINE(_name)					\
+	static struct shell_dummy _name##_shell_dummy;			\
+	struct shell_transport _name = {				\
+		.api = &shell_dummy_transport_api,			\
+		.ctx = (struct shell_dummy *)&_name##_shell_dummy	\
+	}
+
+/**
+ * @brief This function shall not be used directly. It provides pointer to shell
+ *	  dummy backend instance.
+ *
+ * Function returns pointer to the shell dummy instance. This instance can be
+ * next used with shell_execute_cmd function in order to test commands behavior.
+ *
+ * @returns Pointer to the shell instance.
+ */
+const struct shell *shell_backend_dummy_get_ptr(void);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* SHELL_DUMMY_H__ */

include/shell/shell_uart.h

@@ -31,6 +31,16 @@ struct shell_uart {
 		.ctx = (struct shell_uart *)&_name##_shell_uart		\
 	}
 
+/**
+ * @brief This function provides pointer to shell uart backend instance.
+ *
+ * Function returns pointer to the shell uart instance. This instance can be
+ * next used with shell_execute_cmd function in order to test commands behavior.
+ *
+ * @returns Pointer to the shell instance.
+ */
+const struct shell *shell_backend_uart_get_ptr(void);
+
 #ifdef __cplusplus
 }
 #endif

subsys/shell/CMakeLists.txt

@@ -21,7 +21,12 @@ zephyr_sources_ifdef(
 zephyr_sources_ifdef(
   CONFIG_SHELL_BACKEND_SERIAL
   shell_uart.c
-  )
+)
+
+zephyr_sources_ifdef(
+  CONFIG_SHELL_BACKEND_DUMMY
+  shell_dummy.c
+)
 
 zephyr_sources_ifdef(
   CONFIG_SHELL_CMDS

subsys/shell/Kconfig.backends

@@ -21,5 +21,12 @@ config SHELL_BACKEND_SERIAL
 	help
 	  Enable serial backends.
 
+config SHELL_BACKEND_DUMMY
+	bool "Enable dummy backend."
+	select SERIAL
+	help
+	  Enable dummy backend which can be used to test commands with no need
+	  for physical transport interface.
+
 endif # SHELL_BACKENDS
 

subsys/shell/shell.c

@@ -8,6 +8,7 @@
 #include <stdarg.h>
 #include <stdlib.h>
 #include <shell/shell.h>
+#include <shell/shell_dummy.h>
 #include "shell_utils.h"
 #include "shell_ops.h"
 #include "shell_wildcard.h"
@@ -1748,7 +1749,7 @@ int shell_execute_cmd(const struct shell *shell, const char *cmd)
 {
 	u16_t cmd_len = shell_strlen(cmd);
 
-	if ((cmd == NULL) || (shell == NULL)) {
+	if (cmd == NULL) {
 		return -ENOEXEC;
 	}
 
@@ -1756,8 +1757,17 @@ int shell_execute_cmd(const struct shell *shell, const char *cmd)
 		return -ENOEXEC;
 	}
 
+	if (shell == NULL) {
+#if CONFIG_SHELL_BACKEND_DUMMY
+		shell = shell_backend_dummy_get_ptr();
+#else
+		return -EINVAL;
+#endif
+	}
+
 	strcpy(shell->ctx->cmd_buff, cmd);
 	shell->ctx->cmd_buff_len = cmd_len;
+	shell->ctx->cmd_buff_pos = cmd_len;
 
 	return shell_execute(shell);
 }

subsys/shell/shell_dummy.c

@@ -0,0 +1,102 @@
+/*
+ * Copyright (c) 2018 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <shell/shell_dummy.h>
+#include <init.h>
+
+SHELL_DUMMY_DEFINE(shell_transport_dummy);
+SHELL_DEFINE(dummy_shell, "~$ ", &shell_transport_dummy, 10,
+	     SHELL_FLAG_OLF_CRLF);
+
+static int init(const struct shell_transport *transport,
+		const void *config,
+		shell_transport_handler_t evt_handler,
+		void *context)
+{
+	struct shell_dummy *sh_dummy = (struct shell_dummy *)transport->ctx;
+
+	if (sh_dummy->initialized) {
+		return -EINVAL;
+	}
+
+	sh_dummy->initialized = true;
+
+	return 0;
+}
+
+static int uninit(const struct shell_transport *transport)
+{
+	struct shell_dummy *sh_dummy = (struct shell_dummy *)transport->ctx;
+
+	if (sh_dummy->initialized == false) {
+		return -EINVAL;
+	}
+
+	sh_dummy->initialized = false;
+
+	return 0;
+}
+
+static int enable(const struct shell_transport *transport, bool blocking)
+{
+	struct shell_dummy *sh_dummy = (struct shell_dummy *)transport->ctx;
+
+	if (sh_dummy->initialized == false) {
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int write(const struct shell_transport *transport,
+		 const void *data, size_t length, size_t *cnt)
+{
+	struct shell_dummy *sh_dummy = (struct shell_dummy *)transport->ctx;
+
+	if (!sh_dummy->initialized) {
+		*cnt = 0;
+		return -EINVAL;
+	}
+
+	*cnt = length;
+	return 0;
+}
+
+static int read(const struct shell_transport *transport,
+		void *data, size_t length, size_t *cnt)
+{
+	struct shell_dummy *sh_dummy = (struct shell_dummy *)transport->ctx;
+
+
+	if (sh_dummy->initialized) {
+		return -EINVAL;
+	}
+
+	*cnt = 0;
+
+	return 0;
+}
+
+const struct shell_transport_api shell_dummy_transport_api = {
+	.init = init,
+	.uninit = uninit,
+	.enable = enable,
+	.write = write,
+	.read = read
+};
+
+static int enable_shell_dummy(struct device *arg)
+{
+	ARG_UNUSED(arg);
+	shell_init(&dummy_shell, NULL, true, true, LOG_LEVEL_INF);
+	return 0;
+}
+SYS_INIT(enable_shell_dummy, POST_KERNEL, 0);
+
+const struct shell *shell_backend_dummy_get_ptr(void)
+{
+	return &dummy_shell;
+}

subsys/shell/shell_uart.c

@@ -100,3 +100,8 @@ static int enable_shell_uart(struct device *arg)
 	return 0;
 }
 SYS_INIT(enable_shell_uart, POST_KERNEL, 0);
+
+const struct shell *shell_backend_uart_get_ptr(void)
+{
+	return &uart_shell;
+}