Abstract:
Electrical components and associated processes for enhancing automated test of a system by permitting automated generation and application (injection) of real-world stimuli applied to the system under test without the need for manual intervention. Electrical components of the present invention intercede in the exchange of signals and power over various signaling paths within a system under test. Under programmable control by methods of the invention, the electrical components of the present invention may simulate any desired real-world stimulus on any signal path associated with the system under test. Automated test procedures associated with the electrical components may then automate all phases of a test procedure including setup of the test environment, application of real-world stimuli, verification of operation of the system under test and cleanup and recovery following performance of the automated test sequence.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The invention generally relates to automated testing systems and more specifically relates to circuit structures and systems for improved automated testing of electrical interfaces in systems under test.  
           [0003]    2. Discussion of Related Art  
           [0004]    In electronic systems it is common for components within a system to be interconnected via electronic signal buses. Signals are exchanged among the various components of a system through such electronic buses. For example, in a computer storage subsystem, a storage controller within the storage subsystem may be coupled to host computers via an I/O interface bus and may be coupled to other components within the storage subsystem via internal electronic signal buses. Further, components within such a storage subsystem may be coupled to power supply signal paths to receive electrical power during normal operation.  
           [0005]    When testing such systems in a manufacturing environment it is important to test the various interface bus connections and power supply connections to verify proper operation of the subsystem in response to various common operating environments and common failure modes. For example, if the operation of a subsystem is specified to behave in a certain respect in response to changes in power status or loss of power, it is important to simulate such a loss of power and verify the proper operation of a system. For example, it may be important to verify proper operation of the subsystem in response to sensing connection and disconnection of various components within the subsystem. Still more specifically, with regard to a storage subsystem, it may be important to verify operation of the system in response to power failure, removal or insertion of disk drive storage units, host interface bus failures, and other common failure modes of a storage subsystem.  
           [0006]    It is also generally known in the art to automate the process of testing manufactured devices by applying external stimuli to the subsystem and verifying proper response of the subsystem in response to the various stimuli. Such automated test systems generally use a computer system programmed with an automated test sequence application. The automated test application follows a sequence of commands to perform certain desired tests on the system under test. The commands may be provided to the test application as, for example, scripts of commands to be interpreted by the test application. The commands instruct the test application to generate sequences of test data for testing normal operation of the system under test. The test application then cooperates with other elements in the host system to communicate the desired test data to the system under test and verifies proper operation of the system under test in response to the generated test data.  
           [0007]    In addition to testing proper operation of the subsystem in response to programmable sequences of test data, failure modes as noted above often involve changes to the “real-world” environment in which the system under test is functioning. Simulating such failure modes typically requires manual intervention in the testing process. For example, to verify proper operation of a system under test in response to loss of power, manual intervention is typically required to remove power supplied to the system under test. The test application then verifies proper operation of the system under test in response to the manually generated stimulus. Or, for example, in the case of automated testing of a storage subsystem, manual intervention may be required to remove or insert a disk drive to verify operation of the subsystem in response thereto.  
           [0008]    It is generally a problem to require manual intervention in a testing process. Manual intervention introduces a probability of human error in the automated testing process and also slows the automated testing process when manual intervention is required. It is therefore evident from the above discussion that a need exists for improved automated testing procedures and systems to reduce or eliminate reliance on manual intervention for testing operation of a system in response to “real-world” stimuli.  
         SUMMARY OF THE INVENTION  
         [0009]    The present intervention solves the above and other problems, thereby advancing the state of the useful arts, by providing enhanced systems and methods to automate simulation of “real-world” environmental conditions and to verify response of the system under test in response to such real-world stimuli. In general, the present invention provides electrical components (also referred to herein as switching devices) designed to intervene in the normal exchange of signals and power over interface buses and power signal buses within a system under test. These switching devices are coupled through a standard communications interface to the automated testing subsystem operable to perform automated testing on the system under test. The automated testing system is then adapted to command the electrical components to simulate real-world conditions without the need for human intervention. The automated test system may thereby generate real-world stimuli automatically and verify proper operation of the system under test in response thereto.  
           [0010]    These enhanced systems and processes of the present invention serve to centralize control of real-world interfaces to be driven by a single test application. Through the communications interface with the enhanced components, a common software interface may be used by the automated test application to control all real-world interfaces in the automated test sequence. This test architecture therefore allows an automated test application to control all phases of a test sequence including setup of the test environment, verification of the system operation and recovery or cleanup of environmental conditions following the test sequence—all without requiring manual intervention. Eliminating the need for manual intervention also enables continuous (i.e., 24×7) test operation to thereby improve productivity of a test function. Furthermore, this enhanced automated test architecture is easily expandable to utilize new, previously unknown real-world interfaces by providing other variants of switching device to intercept and inject signals associated with the interfaces.  
           [0011]    A feature of the invention therefore provides an apparatus for enhanced automated testing of a system under test, the apparatus comprising: an automated test system for applying stimuli to the system under test and for verifying proper operation of the system under test in response to the stimuli; a switching device for controllably applying stimuli to the system under test; and a communication medium coupling the automated test system to the switching device to enable control of the switching device by the automated test system.  
           [0012]    Another aspect of the invention further provides that the switching device comprises: a logic level switching device to switch logic signals within the system under test as the stimuli thereto.  
           [0013]    Another aspect of the invention further provides that the switching device comprises: a power relay switching device to switch power signals within the system under test as the stimuli thereto.  
           [0014]    Another aspect of the invention further provides that the communication medium is a serial interface.  
           [0015]    Another aspect of the invention further provides that the communication medium is a network communication medium.  
           [0016]    Another aspect of the invention further provides that the system under test is a storage subsystem including a storage controller, a storage device and an interface bus and such that the switching device comprises: a logic level drive device coupled to the interface bus between the storage controller and the storage device to simulate signals exchanged there between via the interface bus.  
           [0017]    Another aspect of the invention further provides that the logic level drive device further comprises: a storage device present signal path to simulate removal and insertion of the storage unit.  
           [0018]    Another aspect of the invention further provides that the system under test is a storage subsystem including a storage controller, a power supply device and a power bus and such that the switching device comprises: a power relay drive device coupled to the interface bus between the storage controller and the storage device to simulate power signals exchanged there between via the power bus.  
           [0019]    Another aspect of the invention further provides that the power relay drive device further comprises: a power signal path to simulate removal and application of power signals from the power supply device to the storage controller.  
           [0020]    Another aspect of the invention further provides that the power supply device is a battery power supply device.  
           [0021]    Another feature of the invention provides a method for testing a system under test comprising the steps of: detecting a need for a real-world stimulus to be applied to the system under test; and providing the real-world stimulus without manual intervention.  
           [0022]    Another aspect of the invention further provides that the step of detecting includes the step of: interpreting a test command requesting generation and application of the real-world stimulus.  
           [0023]    Another aspect of the invention further provides that the step of providing includes the steps of: generating the real-world stimulus without manual intervention; and applying the real-world stimulus to the system under test without manual intervention.  
           [0024]    Another aspect of the invention further provides that the step of providing includes the step of: controlling a driver element to controllably generate the real-world stimulus and to controllably apply the generated real-world stimulus to the system under test.  
           [0025]    Another aspect of the invention further provides that the step of controlling includes the steps of: determining a signal type associated with the real-world stimulus such that the driver element corresponds to the signal type.  
           [0026]    Another aspect of the invention further provides that the signal type is a logic signal and such that the driver element is a logic level driver element.  
           [0027]    Another aspect of the invention further provides that the signal type is a power signal and such that the driver element is a power relay driver element.  
           [0028]    Another feature of the invention provides an apparatus for enabling automated testing of a system under test by a test system, the apparatus comprising: a signal driver element including: means for coupling the driver element to a signal path of the system under test; communication means for communicating between the signal driver element and the test system; and signal means for controllably intercepting and injecting signals on the signal path in response to requests received from the test system via the communication means.  
           [0029]    Another aspect of the invention further provides that the signal path is a logic signal path and such that the signal means controllably intercepts and injects logic signals on the signal path.  
           [0030]    Another aspect of the invention further provides that the signal path is a power signal path and such that the signal means controllably intercepts and injects power signals on the signal path. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0031]    [0031]FIG. 1 is a block diagram depicting enhanced automated test features integrated with a system under test in accordance with the present invention.  
         [0032]    [0032]FIG. 2 is a flowchart describing a method of operation for an automated test system utilizing the enhanced features a FIG. 1 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0033]    While the invention is susceptible to various modifications and alternative forms, a specific embodiment thereof has been shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that it is not intended to limit the invention to the particular form disclosed, but on the contrary, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.  
         [0034]    [0034]FIG. 1 is a block diagram depicting switching elements integrated with the automated test features of a system for improved automated testing of a system under test  110 . System under test  110  may be any type of system that benefits from an automated test capability. Key to such a system is a plurality of components within the system interconnected by electrical signaling paths or buses including, for example, logic signal buses and power distribution buses. As shown in FIG. 1, system under test  110  may be, for example, a storage array subsystem including one or more storage devices  112  electronically coupled to a storage controller  116 . Power supply  118  and an optional battery backup power supply  114  both supply electrical power to storage devices  112  and to storage controller  116  via appropriate power distribution buses within the storage array subsystem  110  (system under test).  
         [0035]    A host computing system  100  and is preferably coupled to system under test  110  via communication path  150 . A software component  106  within host system  100  provides standard application-specific interaction with the system under test  110 . For example, where system under test  110  is a storage array subsystem, system under test application  106  within host system  100  provides standard storage management features for storage and retrieval of information to and from the storage array subsystem.  
         [0036]    In a test environment operable within host system  100 , automated test application  104  coordinates sequences of operations to be performed to verify proper operation of the system under test  110 . Frequently, automated test application  104  is operable to interpret scripts of commands indicating particular sequences of operations to be performed and verified to fully test proper operation of system under test  110 . Those of ordinary skill in the art will recognize a variety of programming styles and paradigms that may be used to construct an automated test application  104 . Interpretive script processing is therefore intended merely as exemplary of one such of well known automated test application design.  
         [0037]    Automated test application  104  may interact with a scheduler component  102  and system under test application  106  to coordinate timing of the desired sequences of commands and to verify proper operation of the system under test  110 . In general, automated test application  104  generates a number of stimuli to be applied to the system under test and then verifies proper operation of the system under test in response to application of each such stimulus. As is well known in the art, such stimuli may include sequences of commands, data and status information to be exchanged between host system  100  and system under test  110  via communication path  150 .  
         [0038]    In addition, as noted above, it is critical in thorough testing of a system under test of that real-world stimuli be applied to the system under test to verify proper operation in response to such real-world environmental stimuli. Examples of such real-world environmental stimuli include removal or application of power signals associated components of the system under test and generation or modification of logic level signals associated with components of the system under test. As noted above, as presently practiced in the art, such real-world environmental stimuli generally require manual intervention by a human operator. Such human intervention introduces opportunities for errors in the testing procedure and dramatically slows the test process by requiring the otherwise automated test procedure to wait for human interaction to proceed further on a test.  
         [0039]    In accordance with the present invention, signal switching elements  122  through  128  are coupled to bus structures  154  through  160  of system under test  110  to permit interception, generation and injection of signals within system under test  110  via automated testing processes operable within host system  100 . Switching devices  122  through  128 , under control of host system  100 , therefore enable automated test processing to include generation of real-world environmental stimuli and application of such stimuli to the system under test without the need for manual intervention. More specifically, switching devices  122  through  128  are coupled to internal bus structures  154  through  160  of system under test  110  to intercept, generate and inject signals to be exchanged between the various components  112  through  118  of system under test  110 . Still more specifically, where system under test  110  is, for example, a storage array subsystem, switching devices  122  through  128  may intercept, generate and inject signals exchanged between storage controller  116  and storage devices  112  as well as power supply signals exchanged between power supply  114  or  118  and storage controller  116  and storage devices  112 .  
         [0040]    In a preferred embodiment, switching devices  122  through  128  comprise at least two different forms of switching elements. A first type of switching device preferably uses standard integrated circuitry and/or discrete electronic components to intercept, generate and inject logic level signals on buses interconnecting components of the system under test (or on buses connecting the system under test with a host system). For example, logic level drivers  122  and  126  are coupled via bus  154  and  158 , respectively, to storage devices  112  and storage controller  116 , respectively. These logic level drivers  122  and  126  are capable of intercepting, generating and injecting logic level signals to simulate desired stimuli in signals exchanged between, for example, storage controller  116  and storage devices  112 .  
         [0041]    A second type of switching device in one preferred embodiment uses power relay switching devices to intercept, generate and inject power signals to be applied to devices within system under test  110 . For example, as shown in FIG. 1, power relay driver  124  may intercept, generate or inject signals via bus  156  to generate stimuli associated with battery power supply  114 . In like manner power relay driver  128  may intercept, generate and inject power signals associated with power supply  118  via bus  160 .  
         [0042]    Switching devices  122  through  128  are preferably coupled via communication path  152  to automated test communication element  108  within host system  100 . Automated test application  104  within host system  100  preferably communicates with switching devices  122  through  128  in cooperation with automated test communication element  108 . Signals exchanged with switching devices  122  through  128  via path  152  instruct the switching devices regarding the nature and timing of desired stimuli for simulation of changes in real-world environmental aspects of operation of the system under test  110 .  
         [0043]    Switching devices  122  through  128  and associated software control elements operable within host system  100  therefore provide full automation for testing of system under test  110  including the automatic generation of real-world environmental stimuli and verification of operation in response thereto. These features permit fully automated testing of the system under test obviating the need for manual intervention in the performance of particular tests. As noted above, this allows for more accurate test procedures by reducing possibility of human error and also enables nonstop testing procedures devoid of the need for human intervention.  
         [0044]    Those of ordinary skill in the art will recognize a variety of equivalent configurations and topologies for the components depicted in FIG. 1. In particular, those of ordinary skill in the art will readily recognize that system under test  110  may be any electronic subsystem having at least one component exchanging logic level signals and/or power signals with another component—typically via a bus structure. The storage array subsystem as shown in FIG. 1 is therefore intended merely as exemplary of a number of such systems. Further, those of ordinary skill in the art will readily recognize that switching elements  122  through  128  are preferably physically positioned and electronically coupled in such a manner as to intercept signals on such buses associated with the system under test. Various forms of cabling and connector techniques well known to those of ordinary skill in the art allow for such a device to be inserted within a signal exchange path of the system under test. Further, those of ordinary skill in the art will clearly recognize that the particular components shown within host system  100  are merely intended as suggestive of one possible functional decomposition of operating components within the host system. Numerous other functional representations will be apparent to those of ordinary skill in the art. Still further, those of ordinary skill in the art will recognize that bus structures  154  through  160  represent any of several well known bus structures commercially available or may represent customized, application-specific bus structures unique to the particular environment. Switching devices  154  through  160  require only that they be positioned physically and electrically to allow interception, generation and injection of signals exchanged over the various buses. Communication path  152  and  150  may be any of several well known to communication media and may use any protocols well known to those of ordinary skill in the art. For example, in one preferred embodiment, communication path  152  may be a simple RS-232 serial communication line where the interaction between host system  100  and the switching elements  122  through  128  includes a low volume of information. In the alternative where a higher bandwidth communication is required for transferring larger volumes of data, communication path  152  may be a network communication path providing higher speed and higher reliability. In like manner, communication path  150  between host system  100  and system under test  110  may be any well known or custom communication path appropriate to the standard operation of system under test  110  by host system  100 .  
         [0045]    [0045]FIG. 2 is a flowchart describing operation of an automated test process utilizing the enhanced features of the present intention to enable automated test processing to include real-world stimulus test procedures. Those skilled in the art will recognize that a test process may be performed requiring manual intervention for generating real-world stimuli as presently practiced in the art or may be performed in a totally automated process in accordance with the present invention. In addition, the present invention permits a hybrid approach incorporating both manual processes and fully automated processes to generate real-world stimuli to be applied to a system under test. In essence, a method of the present invention tests whether a desired real-world stimulus is available for automated generation and application (i.e., is associated with a corresponding logic level driver or power relay driver element). If so, the stimulus is provided by automated means and processes in accordance with the invention. If the requested stimulus is not associated with a corresponding driver element, then manual intervention is required and solicited to generate and apply the real-world stimulus to the system under test. Those skilled in the art will recognize that the invention pertains to provision of such automated test procedures as well as automated procedures combined with such known manual procedures where automated processes are not available.  
         [0046]    Element  200  is first operable to initiate the automated test process. Standard automated test processing including script interpretation and execution continues until element  202  detects a requirement for generation of a real-world, environmental stimulus as specified in the automated test process. When such a real-world stimulus request is detected by operation of element  202  (i.e., by processing of a script directive), element  204  next determines whether the requested stimulus is for simulation of a logic level signal. If so, element  206  is next operable to determine whether an appropriate logic level driver switching element is configured for use in simulating the desired real-world stimulus—in other words determining whether the requested signal path is coupled to a logic level driver in the system. If so, element  208  provides the desired automated logic level stimulus by appropriate control of the associated logic level driver. Automated test processing then continues by looping back to element  202  to await a next requirement for a real-world stimulus.  
         [0047]    Where element  204  determines that the requested real-world stimulus is for other than a logic level signal, processing continues at element  210  presuming that the requested real-world stimulus is for simulation of a power related signal. Element  210  therefore determines whether a power relay driver switching element is associated with the signal to be simulated. If so, processing continues with element  212  to provide the requested power signal stimulus simulation. Processing then continues with further automated testing simulation by looping back to element  202  to await a next request for a real-world environmental stimulus.  
         [0048]    If either element  206  or element  210  determines that no appropriate driver switching element is associated with the requested real-world stimulus signal, processing continues at element  214  to resort to well known manual processing techniques. Specifically, element  214  prompts a human operator to provide the appropriate requested real-world stimulus. Element  216  then awaits an indication from the human user that the requested real-world environmental stimulus has been supplied. Processing then continues by looping back to element  202  to await a next request for real-world, environmental stimulus. Elements  214  and  216  therefore provide a mechanism for standard manual processing of the requested real-world stimulus where the enhanced features of the present intention are not available or not configured for use to simulate the requested signal.  
         [0049]    Those of ordinary skill in the art will readily recognize that in one exemplary application of the features of the present intention, logic signals relating to interaction between a storage controller and storage devices within a storage subsystem may be intercepted and simulated by appropriately configured logic level driver switching elements under control of the process of FIG. 2. For example, simulation of removal or insertion of a disk drive in a storage subsystem under test may be simulated by generation and application (injection) of appropriate signals indicating the presence or absence of a particular disk drive in the subsystem. In like manner, application or removal of power to components of the storage subsystem may be simulated by control of appropriately configured power relay driver switching elements in accordance with the method of FIG. 2. For example, loss of power to a storage controller within a storage subsystem may be simulated by generation and application (injection) of appropriate signals within a power relay driver switching element.  
         [0050]    Still further, those of ordinary skill in the art will recognize that the overall sequence and operation of test process depicted in FIG. 2 is merely intended as exemplary of one possible design. Those of ordinary skill in art will readily recognize numerous equivalent sequences and structures for performing automated test sequences on electronic systems under test.  
         [0051]    While the invention has been illustrated and described in the drawings and foregoing description, such illustration and description is to be considered as exemplary and not restrictive in character, it being understood that only the preferred embodiment and minor variants thereof have been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected.