投稿時間:2021-07-17 10:05:53 RSSフィード2021-07-17 10:00 分まとめ(7件)

カテゴリー等	サイト名等	記事タイトル・トレンドワード等	リンクURL	頻出ワード・要約等/検索ボリューム	登録日
IT	ITmedia 総合記事一覧	[ITmedia News] 相手に触れる立体映像テレプレゼンス　東京大学「Super Haptoclone」開発	https://www.itmedia.co.jp/news/articles/2107/17/news032.html	itmedia	2021-07-17 09:26:00
TECH	Techable（テッカブル）	瞬間移動して遠隔地を観光！ ANA発のスタートアップavatarinがロボットを使った新サービスを提供へ	https://techable.jp/archives/158293	avatarin	2021-07-17 00:00:13
Program	[全てのタグ]の新着質問一覧｜teratail（テラテイル）	laravel フォローボタンの切り替え	https://teratail.com/questions/349918?rss=all	laravelフォローボタンの切り替えLaravelnbspフォロ機能実装でフォロー解除ボタンとフォローボタンの表示の切り替えをif文で行いたいです。	2021-07-17 09:49:15
Program	[全てのタグ]の新着質問一覧｜teratail（テラテイル）	Python dataframe の要素を置換する際、列はラベル、行はインデックスで対象の要素を指定したい	https://teratail.com/questions/349917?rss=all	Pythondataframeの要素を置換する際、列はラベル、行はインデックスで対象の要素を指定したいpandasnbspdataframenbspの要素を置換する際、対象の要素を、列はラベル名、行はインデックスで指定する方法を教えていただけませんでしょうか。	2021-07-17 09:30:38
海外TECH	DEV Community	Explain the implementation principle of the Jest framework in a simple way	https://dev.to/wscats/explain-the-implementation-principle-of-the-jest-framework-in-a-simple-way-4dio	Explain the implementation principle of the Jest framework in a simple way Jest Architecture What is JestJest is a Javascript testing framework developed by Facebook It is a JavaScript library for creating running and writing tests Jest is released as an NPM package and can be installed and run in any JavaScript project Jest is currently one of the most popular test libraries for the front end What does testing meanIn technical terms testing means checking whether our code meets certain expectations For example a function called sum sum should return the expected output given some operation result There are many types of tests and you will soon be overwhelmed by the terminology but the long story short tests fall into three categories unit testIntegration TestingEE test How do I know what to testIn terms of testing even the simplest code block may confuse beginners The most common question is how do I know what to test If you are writing a web page a good starting point is to test every page of the application and every user interaction However the web page also needs to be composed of code units such as functions and modules to be tested There are two situations most of the time You inherit the legacy code which has no built in testsYou must implement a new feature out of thin airso what should I do now In both cases you can think of the test as checking whether the function produces the expected result The most typical test process is as follows Import the function to be testedGive the function an inputDefine the desired outputCheck if the function produces the expected outputGenerally it s that simple Master the following core ideas writing tests will no longer be scary Input gt Expected output gt Assertion result Test blocks assertions and matchersWe will create a simple Javascript function code for the addition of numbers and write a corresponding Jest based test for itconst sum a b gt a b Now for testing create a test file in the same folder and name it test spec js This special suffix is ​​a Jest convention and is used to find all test files We will also import the function under test in order to execute the code under test Jest tests follow the BDD style of tests Each test should have a main test test block and there can be multiple test blocks Now you can write test blocks for the sum method Here we write a test to add Number and verify the expected result We will provide the numbers and and expect to be output test It requires two parameters a string to describe the test block and a callback function to wrap the actual test expect wraps the objective function and combines it with the matcher toBe to check whether the calculation result of the function meets expectations This is the complete test test sum test gt expect sum toBe We observe the above code and find two points The test block is a separate test block which has the function of describing and dividing the scope that is it represents a general container for the test we want to write for the calculation function sum expect is an assertion This statement uses inputs and to call the sum method in the function under test and expects an output of toBe is a matcher used to check the expected value if the expected result is not met an exception should be thrown How to implement a test blockThe test block is actually not complicated The simplest implementation is as follows We need to store the callback function of the actual test of the test package so we encapsulate a dispatch method to receive the command type and the callback function const test name fn gt dispatch type ADD TEST fn name We need to create a callback function called state globally to save the test The callback function of the test is stored in an array global STATE SYMBOL testBlock The dispatch method only needs to identify the corresponding commands at this time and store the test callback function in the global state const dispatch event gt const fn type name event switch type case ADD TEST const testBlock global STATE SYMBOL testBlock push fn name break How to implement assertions and matchersThe assertion library is also very simple to implement You only need to encapsulate a function to expose the matcher method to satisfy the following formula expect A toBe B Here we implement the commonly used method toBe when the result is not equal to the expectation just throw an error const expect actual gt toBe expected if actual expected throw new Error actual is not equal to expected Actually try catch is used in the test block to catch errors and print stack information to locate the problem In simple cases we can also use the assert module that comes with Node to make assertions Of course there are many more complex assertion methods and the principles are similar in essence CLI and configurationAfter writing the test we need to enter the command in the command line to run the single test Normally the command is similar to the following node jest xxx spec jsThe essence here is to parse the parameters of the command line const testPath process argv slice const code fs readFileSync path join process cwd testPath toString In complex situations you may also need to read the parameters of the local Jest configuration file to change the execution environment etc Here Jest uses third party libraries yargs execa and chalk etc to parse execute and print commands SimulationIn complex test scenarios we must not avoid a Jest term mock mock In the Jest documentation we can find that Jest has the following description of simulation The simulation function erases the actual implementation of the function captures the call to the function and the parameters passed in these calls so that the link between the test codes becomes easy In short a simulation can be created by assigning the following code snippets to functions or dependencies jest mock fs readFile jest fn gt wscats This is a simple simulation example that simulates the return value of the readFile function of the fs module in testing specific business logic How to simulate a functionNext we will study how to implement it The first is jest mock Its first parameter accepts the module name or module path and the second parameter is the specific implementation of the module s external exposure method const jest mock mockPath mockExports const path require resolve mockPath paths require cache path id path filename path loaded true exports mockExports Our solution is actually the same as the implementation of the above test test block You only need to find a place to save the specific implementation method and replace it when the module is actually used later so we save it in require In cache of course we can also store it in the global state The implementation of jest fn is not difficult Here we use a closure mockFn to store the replaced functions and parameters which is convenient for subsequent test inspections and statistics of call data const jest fn impl gt const mockFn args gt mockFn mock calls push args return impl args mockFn originImpl impl mockFn mock calls return mockFn Execution environmentSome students may have noticed that in the testing framework we don t need to manually introduce the functions of test expect and jest Each test file can be used directly so we need to create a run that injects these methods here surroundings V virtual machine and scopeSince everything is ready we only need to inject the methods required for testing into the V virtual machine that is inject the testing scope const context console console Console stdout process stdout stderr process stderr jest expect require test name fn gt dispatch type ADD TEST fn name After injecting the scope we can make the code of the test file run in the V virtual machine The code I passed here is the code that has been processed into a string Jest will do some code processing security processing and SourceMap here For sewing and other operations our example does not need to be so complicated vm runInContext code context Before and after the code is executed the time difference can be used to calculate the running time of a single test Jest will also pre evaluate the size and number of single test files here and decide whether to enable Worker to optimize the execution speed const start new Date const end new Date log xb m s xb m Time end start ms Run single test callbackAfter the execution of the V virtual machine is completed the global state will collect all the packaged test callback functions in the test block Finally we only need to traverse all these callback functions and execute them testBlock forEach async item gt const fn name item try await fn apply this log xb m s xb m √ name passed catch log xb m s xb m × name error Hook functionWe can also add life cycles to the single test execution process such as hook functions such as beforeEach afterEach afterAll and beforeAll Adding the hook function to the above infrastructure is actually injecting the corresponding callback function in each process of executing the test For example beforeEach is placed before the traversal execution test function of testBlock and afterEach is placed on testBlock After traversing the execution of the test function it is very simple You only need to put the right position to expose the hook function of any period testBlock forEach async item gt const fn name item beforeEachBlock forEach async beforeEach gt await beforeEach await fn apply this afterEachBlock forEach async afterEach gt await afterEach And beforeAll and afterAll can be placed before and after all tests of testBlock are completed beforeAllBlock forEach async beforeAll gt await beforeAll testBlock forEach async item gt afterAllBlock forEach async afterAll gt await afterAll At this point we have implemented a simple test framework Based on this we can enrich the assertion method matcher and support parameter configuration and read the personal notes of the source code below jest cliDownload Jest source code and execute it in the root directoryyarnnpm run buildIt essentially runs two files build js and buildTs js in the script folder scripts build yarn build js amp amp yarn build ts build js node scripts build js build ts node scripts buildTs js build js essentially uses the babel library create a new build folder in the package xxx package and then use transformFileSync to generate the file into the build folder const transformed babel transformFileSync file options code And buildTs js essentially uses the tsc command to compile the ts file into the build folder and use the execa library to execute the command const args tsc b packagesWithTs process argv slice await execa yarn args stdio inherit Successful execution will display as follows it will help you compile all files js files and ts files in the packages folder to the build folder of the directory where you are Next we can start the jest command npm run jest Equivalent to node packages jest cli bin jest jsHere you can do analysis processing according to the different parameters passed in such as npm run jest hnode packages jest cli bin jest js path test spec jsIt will execute the jest js file and then enter the run method in the build cli file The run method will parse various parameters in the command The specific principle is that the yargs library cooperates with process argv to achieveconst importLocal require import local if importLocal filename if process env NODE ENV null process env NODE ENV test require build cli run jest configWhen various command parameters are obtained the core method of runCLI will be executed which is the core method of the jest core gt packages jest core src cli index ts library import runCLI from jest core const outputStream argv json argv useStderr process stderr process stdout const results globalConfig await runCLI argv projects The runCLI method will use the input parameter argv parsed in the command just now to read the configuration file information with the readConfigs method readConfigs comes from packages jest config src index ts here There will be normalize to fill in and initialize some default configured parameters Its default parameters are recorded in the packages jest config src Defaults ts file For example if you only run js single test the default setting of require resolve jest runner is a runner that runs a single test and it also cooperates with the chalk library to generate an outputStream to output the content to the console By the way let me mention the principle of introducing jest into the module First require resolve moduleName will find the path of the module and save the path in the configuration and then use the tool library packages jest util src requireOrImportModule TherequireOrImportModulemethod of ts calls the encapsulated native import reqiure method to match the path in the configuration file to take out the module globalConfig configuration from argvconfigs are from the configuration of jest config jsconst globalConfig configs hasDeprecationWarnings await readConfigs argv projects if argv debug code if argv showConfig code if argv clearCache code if argv selectProjects code jest haste mapjest haste map is used to get all the files in the project and the dependencies between them It achieves this by looking at the import require calls extracting them from each file and constructing a map containing each A file and its dependencies Here Haste is the module system used by Facebook It also has something called HasteContext because it has HasteFS Haste File System HasteFS is just a list of files in the system and all dependencies associated with it Item it is a map data structure where the key is the path and the value is the metadata The contexts generated here will be used until the onRunComplete stage const contexts hasteMapInstances await buildContextsAndHasteMaps configs globalConfig outputStream jest runnerThe run method will obtain contexts according to the configuration information globalConfig and configs contexts will store the configuration information and path of each local file etc and then will bring the callback function onComplete the global configuration globalConfig and scope contexts enter the runWithoutWatch method Next you will enter the runJest method of the packages jest core src runJest ts file where the passed contexts will be used to traverse all unit tests and save them in an array let allTests Array lt Test gt contexts map async context index gt const searchSource searchSources index const matches await getTestPaths globalConfig searchSource outputStream changedFilesPromise amp amp await changedFilesPromise jestHooks filter allTests allTests concat matches tests return context matches And use the Sequencer method to sort the single testsconst Sequencer typeof TestSequencer await requireOrImportModule globalConfig testSequencer const sequencer new Sequencer allTests await sequencer sort allTests The runJest method calls a key method packages jest core src TestScheduler ts s scheduleTests method const results await new TestScheduler globalConfig startRun testSchedulerContext scheduleTests allTests testWatcher The scheduleTests method will do a lot of things it will collect the contexts in the allTests into the contexts collect the duration into the timings array and subscribe to four life cycles before executing all single tests test file starttest file successtest file failuretest case resultThen traverse the contexts and use a new empty object testRunners to do some processing and save it which will call the createScriptTransformer method provided by jest transform to process the imported modules import createScriptTransformer from jest transform const transformer await createScriptTransformer config const Runner typeof TestRunner interopRequireDefault transformer requireAndTranspileModule config runner default const runner new Runner this globalConfig changedFiles this context changedFiles sourcesRelatedToTestsInChangedFiles this context sourcesRelatedToTestsInChangedFiles testRunners config runner runner The scheduleTests method will call the runTests method of packages jest runner src index ts async runTests tests watcher onStart onResult onFailure options return await options serial this createInBandTestRun tests watcher onStart onResult onFailure this createParallelTestRun tests watcher onStart onResult onFailure In the final createParallelTestRun or createInBandTestRun method There will be a runTestInWorker method which as the name suggests is to perform a single test in the worker createInBandTestRun will execute a core method runTest in packages jest runner src runTest ts and execute a method runTestInternal in runJest which will prepare a lot of preparations before executing a single test The thing involves global method rewriting and hijacking of import and export methods await this eventEmitter emit test file start test return runTest test path this globalConfig test context config test context resolver this context sendMessageToJest In the runTestInternal method the fs module will be used to read the content of the file and put it into cacheFS which can be cached for quick reading later For example if the content of the file is json later it can be read directly in cacheFS Also use Date now time difference to calculate time consuming const testSource fs readFileSync path utf const cacheFS new Map path testSource In the runTestInternal method packages jest runtime src index ts will be introduced which will help you cache and read modules and trigger execution const runtime new Runtime config environment resolver transformer cacheFS changedFiles context changedFiles collectCoverage globalConfig collectCoverage collectCoverageFrom globalConfig collectCoverageFrom collectCoverageOnlyFrom globalConfig collectCoverageOnlyFrom coverageProvider globalConfig coverageProvider sourcesRelatedToTestsInChangedFiles context sourcesRelatedToTestsInChangedFiles path Here the jest console package is used to rewrite the global console In order for the console of the single tested file code block to print the results on the node terminal smoothly in conjunction with the jest environment node package set the global environment global all Rewritten to facilitate subsequent methods to get these scopes in vm Essentially it is rewritten using node s console to facilitate subsequent overwriting of the console method in the vm scopetestConsole new BufferedConsole const environment new TestEnvironment config console testConsole Suspected useless code docblockPragmas testPath path Really rewrite the console methodsetGlobal environment global console testConsole runtime mainly uses these two methods to load the module first judge whether it is an ESM module if it is use runtime unstable importModule to load the module and run the module if not use runtime requireModule to load the module and run the module const esm runtime unstable shouldLoadAsEsm path if esm await runtime unstable importModule path else runtime requireModule path jest circusImmediately after the testFramework in runTestInternal will accept the incoming runtime to call the single test file to run the testFramework method comes from a library with an interesting name packages jest circus src legacy code todo rewrite jestAdapter ts where legacy code todo rewrite means legacy code todo rewrite jest circus mainly rewrites some methods of global global involving These few afterAllafterEachbeforeAllbeforeEachdescribeittestBefore calling the single test here the jestAdapter function which is the above mentioned runtime requireModule will load the xxx spec js file The execution environment globals has been preset using initialize before execution AndsnapshotState and rewritebeforeEach IfresetModules clearMocks resetMocks restoreMocksandsetupFilesAfterEnv are configured the following methods will be executed respectively runtime resetModulesruntime clearAllMocksruntime resetAllMocksruntime restoreAllMocksruntime requireModule or runtime unstable importModuleAfter running the initialization of the initialize method because initialize has rewritten the global describe and test methods these methods are all rewritten here in packages jest circus src index ts here Note that there is a dispatchSync method in the test method This is a key method Here a copy of state will be maintained globally dispatchSync means to store the functions and other information in the test code block in the state In dispatchSync uses name in conjunction with the eventHandler method to modify the state This idea is very similar to the data flow in redux const test Global It gt return test testName fn timeout gt testName mode fn testFn timeout gt return dispatchSync asyncError fn mode name add test testName timeout The single test xxx spec js that is the testPath file will be imported and executed after the initialize Note that this single test will be executed when imported here because the single test xxx spec js file is written according to the specifications There will be code blocks such as test and describe so at this time all callback functions accepted by test and describe will be stored in the global state const esm runtime unstable shouldLoadAsEsm testPath if esm await runtime unstable importModule testPath else runtime requireModule testPath jest runtimeHere it will first determine whether it is an esm module if it is use the method of unstable importModule to import it otherwise use the method of requireModule to import it specifically will it enter the following function this loadModule localModule from moduleName modulePath options moduleRegistry The logic of loadModule has only three main partsJudge whether it is a json suffix file execute readFile to read the text and use transformJson and JSON parse to transform the output content Determine whether the node suffix file is and execute the require native method to import the module For files that do not meet the above two conditions execute the execModule execution module execModule will use babel to transform the source code read by fs This transformFile is the transform method of packages jest runtime src index ts const transformedCode this transformFile filename options execModule will use the createScriptFromCode method to call node s native vm module to actually execute js The vm module accepts safe source code and uses the V virtual machine with the incoming context to execute the code immediately or delay the execution of the code here you can Accept different scopes to execute the same code to calculate different results which is very suitable for the use of test frameworks The injected vmContext here is the above global rewrite scope including afterAll afterEach beforeAll beforeEach describe it test So our single test code will get these methods with injection scope when it runs const vm require vm const script new vm Script scriptSourceCode option const filename module filename const vmContext this environment getVmContext script runInContext vmContext filename When the global method is overwritten and the state is saved above it will enter the logic of the callback function that actually executes the describe in the run method of packages jest circus src run ts here Use the getState method to take out the describe code block then use the runTestsForDescribeBlock to execute this function then enter the runTest method and then use the hook function before and after the execution of callCircusHook and use the callCircusTest to execute const run async Promise lt Circus RunResult gt gt const rootDescribeBlock getState await dispatch name run start await runTestsForDescribeBlock rootDescribeBlock await dispatch name run finish return makeRunResult getState rootDescribeBlock getState unhandledErrors const runTest async test parentSkipped gt beforeEach test function block testContext scope await callCircusTest test testContext afterEach This is the core position of the hook function implementation and also the core element of the Jest function At lastI hope this article can help you understand the core implementation and principles of the Jest testing framework Thank you for reading patiently If the articles and notes can bring you a hint of help or inspiration please don t be stingy with your Star and Fork The articles are continuously updated synchronously your affirmation Is my biggest motivation to move forward	2021-07-17 00:30:38
海外科学	BBC News - Science & Environment	UK looks to extend ivory ban to hippos and other animals	https://www.bbc.co.uk/news/uk-politics-57867935	consultation	2021-07-17 00:25:18
ニュース	BBC News - Home	UK looks to extend ivory ban to hippos and other animals	https://www.bbc.co.uk/news/uk-politics-57867935	consultation	2021-07-17 00:25:18