Merge pull request #128799 from hercules-ci/cypress-test

cypress.tests.example: init, jsonplaceholder: init

pkgs/development/node-packages/default.nix

@@ -107,6 +107,19 @@ let
       nativeBuildInputs = drv.nativeBuildInputs or [] ++ [ pkgs.psc-package self.pulp ];
     });
 
+    jsonplaceholder = super.jsonplaceholder.override (drv: {
+      buildInputs = [ nodejs ];
+      postInstall = ''
+        exe=$out/bin/jsonplaceholder
+        mkdir -p $out/bin
+        cat >$exe <<EOF
+        #!${pkgs.runtimeShell}
+        exec -a jsonplaceholder ${nodejs}/bin/node $out/lib/node_modules/jsonplaceholder/index.js
+        EOF
+        chmod a+x $exe
+      '';
+    });
+
     makam =  super.makam.override {
       buildInputs = [ pkgs.nodejs pkgs.makeWrapper ];
       postFixup = ''

pkgs/development/node-packages/node-packages.json

@@ -139,6 +139,7 @@
 , "json-refs"
 , "json-server"
 , "jsonlint"
+, "jsonplaceholder"
 , "kaput-cli"
 , "katex"
 , "karma"

pkgs/development/web/cypress/cypress-example-kitchensink/README.md

@@ -0,0 +1,24 @@
+
+# `cypress-example-kitchensink`
+
+This directory 'packages' [cypress-example-kitchensink](https://github.com/cypress-io/cypress-example-kitchensink),
+which is used in `cypress.passthru.tests`.
+
+The app is not really intended for deployment, so I didn't bother with actual packaging, just testing.
+If your real-world app looks like `cypress-example-kitchensink`, you'll want to use Nix multiple outputs so you don't deploy your test videos along with your app.
+Alternatively, you can set it up so that one derivation builds your server exe and another derivation takes that server exe and runs it with the cypress e2e tests.
+
+## Peculiarities
+
+**cypress and Cypress** are distinct names.
+  - `cypress` is the npm module, containing the executable `cypress`
+  - whereas the executable `Cypress` comes from `pkgs.cypress`, a binary distribution (as of writing) by cypress.io.
+
+**updateScript** is not provided for this example project. This seems preferable,
+  because updates to it aren't particularly valuable and have a significant overhead.
+  The goal is to smoke test `cypress`; not run the latest test suite (which it isn't anyway).
+
+## Updating
+
+ - update the hash in `src.nix`
+ - run `regen-nix`

pkgs/development/web/cypress/cypress-example-kitchensink/cypress-example-kitchensink.nix

@@ -0,0 +1,17 @@
+# This file has been generated by node2nix 1.9.0. Do not edit!
+
+{pkgs ? import <nixpkgs> {
+    inherit system;
+  }, system ? builtins.currentSystem, nodejs ? pkgs."nodejs-12_x"}:
+
+let
+  nodeEnv = import ./node-env.nix {
+    inherit (pkgs) stdenv lib python2 runCommand writeTextFile;
+    inherit pkgs nodejs;
+    libtool = if pkgs.stdenv.isDarwin then pkgs.darwin.cctools else null;
+  };
+in
+import ./node-packages.nix {
+  inherit (pkgs) fetchurl nix-gitignore stdenv lib fetchgit callPackage;
+  inherit nodeEnv;
+}

pkgs/development/web/cypress/cypress-example-kitchensink/default.nix

@@ -0,0 +1,59 @@
+{ callPackage
+, cypress
+, nodejs-12_x
+, # FIXME: duplicated from ./regen-nix. node2nix should expose this
+  nodePackages
+, xorg
+, pkgs
+, stdenv
+,
+}:
+
+let
+  fromNode2nix = import ./cypress-example-kitchensink.nix {
+    inherit pkgs;
+  };
+
+  nodeDependencies = fromNode2nix.shell.nodeDependencies.overrideAttrs (o: {
+    CYPRESS_INSTALL_BINARY = "0";
+    PUPPETEER_SKIP_DOWNLOAD = "1";
+  });
+
+  fontConfigEtc = (
+    pkgs.nixos { config.fonts.fontconfig.enable = true; }
+  ).config.environment.etc.fonts.source;
+
+in
+stdenv.mkDerivation {
+  name = "cypress-example-kitchensink";
+  src = callPackage ./src.nix { };
+  passthru.fc = fontConfigEtc;
+  nativeBuildInputs = [
+    cypress
+    nodejs-12_x
+    xorg.xorgserver
+    nodePackages.jsonplaceholder
+  ];
+  FONTCONFIG_PATH = fontConfigEtc;
+  postPatch = ''
+    # Use our own offline backend. 15011 means js0n ;)
+    sed -e 's^https://jsonplaceholder.cypress.io^http://localhost:15011^g' -i $(find . -type f)
+  '';
+  buildPhase = ''
+    ln -s ${nodeDependencies}/lib/node_modules ./node_modules
+    PATH="${nodeDependencies}/bin:$PATH"
+    runHook preBuild
+    PORT=15011 jsonplaceholder &
+    # assumption: jsonplaceholder start far quicker than cypress run
+
+    export CYPRESS_RUN_BINARY=${cypress}/bin/Cypress
+    export HOME=$PWD/home
+    mkdir $HOME
+    npm run test
+    runHook postBuild
+  '';
+  installPhase = ''
+    mkdir $out
+    cp -r cypress/videos $out/
+  '';
+}

pkgs/development/web/cypress/cypress-example-kitchensink/node-env.nix

@@ -0,0 +1,567 @@
+# This file originates from node2nix
+
+{lib, stdenv, nodejs, python2, pkgs, libtool, runCommand, writeTextFile}:
+
+let
+  # Workaround to cope with utillinux in Nixpkgs 20.09 and util-linux in Nixpkgs master
+  utillinux = if pkgs ? utillinux then pkgs.utillinux else pkgs.util-linux;
+
+  python = if nodejs ? python then nodejs.python else python2;
+
+  # Create a tar wrapper that filters all the 'Ignoring unknown extended header keyword' noise
+  tarWrapper = runCommand "tarWrapper" {} ''
+    mkdir -p $out/bin
+
+    cat > $out/bin/tar <<EOF
+    #! ${stdenv.shell} -e
+    $(type -p tar) "\$@" --warning=no-unknown-keyword --delay-directory-restore
+    EOF
+
+    chmod +x $out/bin/tar
+  '';
+
+  # Function that generates a TGZ file from a NPM project
+  buildNodeSourceDist =
+    { name, version, src, ... }:
+
+    stdenv.mkDerivation {
+      name = "node-tarball-${name}-${version}";
+      inherit src;
+      buildInputs = [ nodejs ];
+      buildPhase = ''
+        export HOME=$TMPDIR
+        tgzFile=$(npm pack | tail -n 1) # Hooks to the pack command will add output (https://docs.npmjs.com/misc/scripts)
+      '';
+      installPhase = ''
+        mkdir -p $out/tarballs
+        mv $tgzFile $out/tarballs
+        mkdir -p $out/nix-support
+        echo "file source-dist $out/tarballs/$tgzFile" >> $out/nix-support/hydra-build-products
+      '';
+    };
+
+  includeDependencies = {dependencies}:
+    lib.optionalString (dependencies != [])
+      (lib.concatMapStrings (dependency:
+        ''
+          # Bundle the dependencies of the package
+          mkdir -p node_modules
+          cd node_modules
+
+          # Only include dependencies if they don't exist. They may also be bundled in the package.
+          if [ ! -e "${dependency.name}" ]
+          then
+              ${composePackage dependency}
+          fi
+
+          cd ..
+        ''
+      ) dependencies);
+
+  # Recursively composes the dependencies of a package
+  composePackage = { name, packageName, src, dependencies ? [], ... }@args:
+    builtins.addErrorContext "while evaluating node package '${packageName}'" ''
+      DIR=$(pwd)
+      cd $TMPDIR
+
+      unpackFile ${src}
+
+      # Make the base dir in which the target dependency resides first
+      mkdir -p "$(dirname "$DIR/${packageName}")"
+
+      if [ -f "${src}" ]
+      then
+          # Figure out what directory has been unpacked
+          packageDir="$(find . -maxdepth 1 -type d | tail -1)"
+
+          # Restore write permissions to make building work
+          find "$packageDir" -type d -exec chmod u+x {} \;
+          chmod -R u+w "$packageDir"
+
+          # Move the extracted tarball into the output folder
+          mv "$packageDir" "$DIR/${packageName}"
+      elif [ -d "${src}" ]
+      then
+          # Get a stripped name (without hash) of the source directory.
+          # On old nixpkgs it's already set internally.
+          if [ -z "$strippedName" ]
+          then
+              strippedName="$(stripHash ${src})"
+          fi
+
+          # Restore write permissions to make building work
+          chmod -R u+w "$strippedName"
+
+          # Move the extracted directory into the output folder
+          mv "$strippedName" "$DIR/${packageName}"
+      fi
+
+      # Unset the stripped name to not confuse the next unpack step
+      unset strippedName
+
+      # Include the dependencies of the package
+      cd "$DIR/${packageName}"
+      ${includeDependencies { inherit dependencies; }}
+      cd ..
+      ${lib.optionalString (builtins.substring 0 1 packageName == "@") "cd .."}
+    '';
+
+  pinpointDependencies = {dependencies, production}:
+    let
+      pinpointDependenciesFromPackageJSON = writeTextFile {
+        name = "pinpointDependencies.js";
+        text = ''
+          var fs = require('fs');
+          var path = require('path');
+
+          function resolveDependencyVersion(location, name) {
+              if(location == process.env['NIX_STORE']) {
+                  return null;
+              } else {
+                  var dependencyPackageJSON = path.join(location, "node_modules", name, "package.json");
+
+                  if(fs.existsSync(dependencyPackageJSON)) {
+                      var dependencyPackageObj = JSON.parse(fs.readFileSync(dependencyPackageJSON));
+
+                      if(dependencyPackageObj.name == name) {
+                          return dependencyPackageObj.version;
+                      }
+                  } else {
+                      return resolveDependencyVersion(path.resolve(location, ".."), name);
+                  }
+              }
+          }
+
+          function replaceDependencies(dependencies) {
+              if(typeof dependencies == "object" && dependencies !== null) {
+                  for(var dependency in dependencies) {
+                      var resolvedVersion = resolveDependencyVersion(process.cwd(), dependency);
+
+                      if(resolvedVersion === null) {
+                          process.stderr.write("WARNING: cannot pinpoint dependency: "+dependency+", context: "+process.cwd()+"\n");
+                      } else {
+                          dependencies[dependency] = resolvedVersion;
+                      }
+                  }
+              }
+          }
+
+          /* Read the package.json configuration */
+          var packageObj = JSON.parse(fs.readFileSync('./package.json'));
+
+          /* Pinpoint all dependencies */
+          replaceDependencies(packageObj.dependencies);
+          if(process.argv[2] == "development") {
+              replaceDependencies(packageObj.devDependencies);
+          }
+          replaceDependencies(packageObj.optionalDependencies);
+
+          /* Write the fixed package.json file */
+          fs.writeFileSync("package.json", JSON.stringify(packageObj, null, 2));
+        '';
+      };
+    in
+    ''
+      node ${pinpointDependenciesFromPackageJSON} ${if production then "production" else "development"}
+
+      ${lib.optionalString (dependencies != [])
+        ''
+          if [ -d node_modules ]
+          then
+              cd node_modules
+              ${lib.concatMapStrings (dependency: pinpointDependenciesOfPackage dependency) dependencies}
+              cd ..
+          fi
+        ''}
+    '';
+
+  # Recursively traverses all dependencies of a package and pinpoints all
+  # dependencies in the package.json file to the versions that are actually
+  # being used.
+
+  pinpointDependenciesOfPackage = { packageName, dependencies ? [], production ? true, ... }@args:
+    ''
+      if [ -d "${packageName}" ]
+      then
+          cd "${packageName}"
+          ${pinpointDependencies { inherit dependencies production; }}
+          cd ..
+          ${lib.optionalString (builtins.substring 0 1 packageName == "@") "cd .."}
+      fi
+    '';
+
+  # Extract the Node.js source code which is used to compile packages with
+  # native bindings
+  nodeSources = runCommand "node-sources" {} ''
+    tar --no-same-owner --no-same-permissions -xf ${nodejs.src}
+    mv node-* $out
+  '';
+
+  # Script that adds _integrity fields to all package.json files to prevent NPM from consulting the cache (that is empty)
+  addIntegrityFieldsScript = writeTextFile {
+    name = "addintegrityfields.js";
+    text = ''
+      var fs = require('fs');
+      var path = require('path');
+
+      function augmentDependencies(baseDir, dependencies) {
+          for(var dependencyName in dependencies) {
+              var dependency = dependencies[dependencyName];
+
+              // Open package.json and augment metadata fields
+              var packageJSONDir = path.join(baseDir, "node_modules", dependencyName);
+              var packageJSONPath = path.join(packageJSONDir, "package.json");
+
+              if(fs.existsSync(packageJSONPath)) { // Only augment packages that exist. Sometimes we may have production installs in which development dependencies can be ignored
+                  console.log("Adding metadata fields to: "+packageJSONPath);
+                  var packageObj = JSON.parse(fs.readFileSync(packageJSONPath));
+
+                  if(dependency.integrity) {
+                      packageObj["_integrity"] = dependency.integrity;
+                  } else {
+                      packageObj["_integrity"] = "sha1-000000000000000000000000000="; // When no _integrity string has been provided (e.g. by Git dependencies), add a dummy one. It does not seem to harm and it bypasses downloads.
+                  }
+
+                  if(dependency.resolved) {
+                      packageObj["_resolved"] = dependency.resolved; // Adopt the resolved property if one has been provided
+                  } else {
+                      packageObj["_resolved"] = dependency.version; // Set the resolved version to the version identifier. This prevents NPM from cloning Git repositories.
+                  }
+
+                  if(dependency.from !== undefined) { // Adopt from property if one has been provided
+                      packageObj["_from"] = dependency.from;
+                  }
+
+                  fs.writeFileSync(packageJSONPath, JSON.stringify(packageObj, null, 2));
+              }
+
+              // Augment transitive dependencies
+              if(dependency.dependencies !== undefined) {
+                  augmentDependencies(packageJSONDir, dependency.dependencies);
+              }
+          }
+      }
+
+      if(fs.existsSync("./package-lock.json")) {
+          var packageLock = JSON.parse(fs.readFileSync("./package-lock.json"));
+
+          if(![1, 2].includes(packageLock.lockfileVersion)) {
+             process.stderr.write("Sorry, I only understand lock file versions 1 and 2!\n");
+             process.exit(1);
+          }
+
+          if(packageLock.dependencies !== undefined) {
+              augmentDependencies(".", packageLock.dependencies);
+          }
+      }
+    '';
+  };
+
+  # Reconstructs a package-lock file from the node_modules/ folder structure and package.json files with dummy sha1 hashes
+  reconstructPackageLock = writeTextFile {
+    name = "addintegrityfields.js";
+    text = ''
+      var fs = require('fs');
+      var path = require('path');
+
+      var packageObj = JSON.parse(fs.readFileSync("package.json"));
+
+      var lockObj = {
+          name: packageObj.name,
+          version: packageObj.version,
+          lockfileVersion: 1,
+          requires: true,
+          dependencies: {}
+      };
+
+      function augmentPackageJSON(filePath, dependencies) {
+          var packageJSON = path.join(filePath, "package.json");
+          if(fs.existsSync(packageJSON)) {
+              var packageObj = JSON.parse(fs.readFileSync(packageJSON));
+              dependencies[packageObj.name] = {
+                  version: packageObj.version,
+                  integrity: "sha1-000000000000000000000000000=",
+                  dependencies: {}
+              };
+              processDependencies(path.join(filePath, "node_modules"), dependencies[packageObj.name].dependencies);
+          }
+      }
+
+      function processDependencies(dir, dependencies) {
+          if(fs.existsSync(dir)) {
+              var files = fs.readdirSync(dir);
+
+              files.forEach(function(entry) {
+                  var filePath = path.join(dir, entry);
+                  var stats = fs.statSync(filePath);
+
+                  if(stats.isDirectory()) {
+                      if(entry.substr(0, 1) == "@") {
+                          // When we encounter a namespace folder, augment all packages belonging to the scope
+                          var pkgFiles = fs.readdirSync(filePath);
+
+                          pkgFiles.forEach(function(entry) {
+                              if(stats.isDirectory()) {
+                                  var pkgFilePath = path.join(filePath, entry);
+                                  augmentPackageJSON(pkgFilePath, dependencies);
+                              }
+                          });
+                      } else {
+                          augmentPackageJSON(filePath, dependencies);
+                      }
+                  }
+              });
+          }
+      }
+
+      processDependencies("node_modules", lockObj.dependencies);
+
+      fs.writeFileSync("package-lock.json", JSON.stringify(lockObj, null, 2));
+    '';
+  };
+
+  prepareAndInvokeNPM = {packageName, bypassCache, reconstructLock, npmFlags, production}:
+    let
+      forceOfflineFlag = if bypassCache then "--offline" else "--registry http://www.example.com";
+    in
+    ''
+        # Pinpoint the versions of all dependencies to the ones that are actually being used
+        echo "pinpointing versions of dependencies..."
+        source $pinpointDependenciesScriptPath
+
+        # Patch the shebangs of the bundled modules to prevent them from
+        # calling executables outside the Nix store as much as possible
+        patchShebangs .
+
+        # Deploy the Node.js package by running npm install. Since the
+        # dependencies have been provided already by ourselves, it should not
+        # attempt to install them again, which is good, because we want to make
+        # it Nix's responsibility. If it needs to install any dependencies
+        # anyway (e.g. because the dependency parameters are
+        # incomplete/incorrect), it fails.
+        #
+        # The other responsibilities of NPM are kept -- version checks, build
+        # steps, postprocessing etc.
+
+        export HOME=$TMPDIR
+        cd "${packageName}"
+        runHook preRebuild
+
+        ${lib.optionalString bypassCache ''
+          ${lib.optionalString reconstructLock ''
+            if [ -f package-lock.json ]
+            then
+                echo "WARNING: Reconstruct lock option enabled, but a lock file already exists!"
+                echo "This will most likely result in version mismatches! We will remove the lock file and regenerate it!"
+                rm package-lock.json
+            else
+                echo "No package-lock.json file found, reconstructing..."
+            fi
+
+            node ${reconstructPackageLock}
+          ''}
+
+          node ${addIntegrityFieldsScript}
+        ''}
+
+        npm ${forceOfflineFlag} --nodedir=${nodeSources} ${npmFlags} ${lib.optionalString production "--production"} rebuild
+
+        if [ "''${dontNpmInstall-}" != "1" ]
+        then
+            # NPM tries to download packages even when they already exist if npm-shrinkwrap is used.
+            rm -f npm-shrinkwrap.json
+
+            npm ${forceOfflineFlag} --nodedir=${nodeSources} ${npmFlags} ${lib.optionalString production "--production"} install
+        fi
+    '';
+
+  # Builds and composes an NPM package including all its dependencies
+  buildNodePackage =
+    { name
+    , packageName
+    , version
+    , dependencies ? []
+    , buildInputs ? []
+    , production ? true
+    , npmFlags ? ""
+    , dontNpmInstall ? false
+    , bypassCache ? false
+    , reconstructLock ? false
+    , preRebuild ? ""
+    , dontStrip ? true
+    , unpackPhase ? "true"
+    , buildPhase ? "true"
+    , ... }@args:
+
+    let
+      extraArgs = removeAttrs args [ "name" "dependencies" "buildInputs" "dontStrip" "dontNpmInstall" "preRebuild" "unpackPhase" "buildPhase" ];
+    in
+    stdenv.mkDerivation ({
+      name = "node_${name}-${version}";
+      buildInputs = [ tarWrapper python nodejs ]
+        ++ lib.optional (stdenv.isLinux) utillinux
+        ++ lib.optional (stdenv.isDarwin) libtool
+        ++ buildInputs;
+
+      inherit nodejs;
+
+      inherit dontStrip; # Stripping may fail a build for some package deployments
+      inherit dontNpmInstall preRebuild unpackPhase buildPhase;
+
+      compositionScript = composePackage args;
+      pinpointDependenciesScript = pinpointDependenciesOfPackage args;
+
+      passAsFile = [ "compositionScript" "pinpointDependenciesScript" ];
+
+      installPhase = ''
+        # Create and enter a root node_modules/ folder
+        mkdir -p $out/lib/node_modules
+        cd $out/lib/node_modules
+
+        # Compose the package and all its dependencies
+        source $compositionScriptPath
+
+        ${prepareAndInvokeNPM { inherit packageName bypassCache reconstructLock npmFlags production; }}
+
+        # Create symlink to the deployed executable folder, if applicable
+        if [ -d "$out/lib/node_modules/.bin" ]
+        then
+            ln -s $out/lib/node_modules/.bin $out/bin
+        fi
+
+        # Create symlinks to the deployed manual page folders, if applicable
+        if [ -d "$out/lib/node_modules/${packageName}/man" ]
+        then
+            mkdir -p $out/share
+            for dir in "$out/lib/node_modules/${packageName}/man/"*
+            do
+                mkdir -p $out/share/man/$(basename "$dir")
+                for page in "$dir"/*
+                do
+                    ln -s $page $out/share/man/$(basename "$dir")
+                done
+            done
+        fi
+
+        # Run post install hook, if provided
+        runHook postInstall
+      '';
+    } // extraArgs);
+
+  # Builds a node environment (a node_modules folder and a set of binaries)
+  buildNodeDependencies =
+    { name
+    , packageName
+    , version
+    , src
+    , dependencies ? []
+    , buildInputs ? []
+    , production ? true
+    , npmFlags ? ""
+    , dontNpmInstall ? false
+    , bypassCache ? false
+    , reconstructLock ? false
+    , dontStrip ? true
+    , unpackPhase ? "true"
+    , buildPhase ? "true"
+    , ... }@args:
+
+    let
+      extraArgs = removeAttrs args [ "name" "dependencies" "buildInputs" ];
+    in
+      stdenv.mkDerivation ({
+        name = "node-dependencies-${name}-${version}";
+
+        buildInputs = [ tarWrapper python nodejs ]
+          ++ lib.optional (stdenv.isLinux) utillinux
+          ++ lib.optional (stdenv.isDarwin) libtool
+          ++ buildInputs;
+
+        inherit dontStrip; # Stripping may fail a build for some package deployments
+        inherit dontNpmInstall unpackPhase buildPhase;
+
+        includeScript = includeDependencies { inherit dependencies; };
+        pinpointDependenciesScript = pinpointDependenciesOfPackage args;
+
+        passAsFile = [ "includeScript" "pinpointDependenciesScript" ];
+
+        installPhase = ''
+          mkdir -p $out/${packageName}
+          cd $out/${packageName}
+
+          source $includeScriptPath
+
+          # Create fake package.json to make the npm commands work properly
+          cp ${src}/package.json .
+          chmod 644 package.json
+          ${lib.optionalString bypassCache ''
+            if [ -f ${src}/package-lock.json ]
+            then
+                cp ${src}/package-lock.json .
+            fi
+          ''}
+
+          # Go to the parent folder to make sure that all packages are pinpointed
+          cd ..
+          ${lib.optionalString (builtins.substring 0 1 packageName == "@") "cd .."}
+
+          ${prepareAndInvokeNPM { inherit packageName bypassCache reconstructLock npmFlags production; }}
+
+          # Expose the executables that were installed
+          cd ..
+          ${lib.optionalString (builtins.substring 0 1 packageName == "@") "cd .."}
+
+          mv ${packageName} lib
+          ln -s $out/lib/node_modules/.bin $out/bin
+        '';
+      } // extraArgs);
+
+  # Builds a development shell
+  buildNodeShell =
+    { name
+    , packageName
+    , version
+    , src
+    , dependencies ? []
+    , buildInputs ? []
+    , production ? true
+    , npmFlags ? ""
+    , dontNpmInstall ? false
+    , bypassCache ? false
+    , reconstructLock ? false
+    , dontStrip ? true
+    , unpackPhase ? "true"
+    , buildPhase ? "true"
+    , ... }@args:
+
+    let
+      nodeDependencies = buildNodeDependencies args;
+    in
+    stdenv.mkDerivation {
+      name = "node-shell-${name}-${version}";
+
+      buildInputs = [ python nodejs ] ++ lib.optional (stdenv.isLinux) utillinux ++ buildInputs;
+      buildCommand = ''
+        mkdir -p $out/bin
+        cat > $out/bin/shell <<EOF
+        #! ${stdenv.shell} -e
+        $shellHook
+        exec ${stdenv.shell}
+        EOF
+        chmod +x $out/bin/shell
+      '';
+
+      # Provide the dependencies in a development shell through the NODE_PATH environment variable
+      inherit nodeDependencies;
+      shellHook = lib.optionalString (dependencies != []) ''
+        export NODE_PATH=${nodeDependencies}/lib/node_modules
+        export PATH="${nodeDependencies}/bin:$PATH"
+      '';
+    };
+in
+{
+  buildNodeSourceDist = lib.makeOverridable buildNodeSourceDist;
+  buildNodePackage = lib.makeOverridable buildNodePackage;
+  buildNodeDependencies = lib.makeOverridable buildNodeDependencies;
+  buildNodeShell = lib.makeOverridable buildNodeShell;
+}

pkgs/development/web/cypress/cypress-example-kitchensink/regen-nix

@@ -0,0 +1,21 @@
+#!/usr/bin/env nix-shell
+#!nix-shell ./regen-nix.nix
+#!nix-shell -i bash
+
+node2nix \
+  --nodejs-12 \
+  --input $src/package.json \
+  --lock $src/package-lock.json \
+  --composition cypress-example-kitchensink.nix \
+  --development \
+  ;
+
+# node2nix produces opinionated expressions that work for in-repo packaging
+# but aren't ideal for Nixpkgs:
+sed -i cypress-example-kitchensink.nix \
+  -e 's^fetchgit^fetchgit callPackage^'
+sed -i node-packages.nix \
+  -e 's^fetchgit, ^fetchgit, callPackage, ^' \
+  -e 's^src = .*/nix/store/.*-source^src = callPackage ./src.nix {}^' \
+  -e 's^nix-gitignore.gitignoreSourcePure^(ignore: src: src)^' \
+  ;

pkgs/development/web/cypress/cypress-example-kitchensink/regen-nix.nix

@@ -0,0 +1,8 @@
+{ pkgs ? import ../../../../.. { config = { }; overlays = [ ]; } }:
+
+pkgs.mkShell {
+  nativeBuildInputs = [
+    pkgs.nodePackages.node2nix
+  ];
+  src = pkgs.callPackage ./src.nix { };
+}

pkgs/development/web/cypress/cypress-example-kitchensink/src.nix

@@ -0,0 +1,6 @@
+{ fetchFromGitHub }: fetchFromGitHub {
+  owner = "cypress-io";
+  repo = "cypress-example-kitchensink";
+  rev = "1572887a2003c2f35ff46d14f5f1cdfef975c9be";
+  sha256 = "sha256-A7d95b9V707iOzlIg+3nItPPB8HNVVOjPhGqa8MXRPE=";
+}

pkgs/development/web/cypress/default.nix

@@ -1,4 +1,19 @@
-{ stdenv, lib, fetchzip, autoPatchelfHook, xorg, gtk2, gnome2, gtk3, nss, alsa-lib, udev, unzip, wrapGAppsHook, mesa }:
+{ alsa-lib
+, autoPatchelfHook
+, callPackage
+, fetchzip
+, gnome2
+, gtk2
+, gtk3
+, lib
+, mesa
+, nss
+, stdenv
+, udev
+, unzip
+, wrapGAppsHook
+, xorg
+}:
 
 stdenv.mkDerivation rec {
   pname = "cypress";
@@ -9,17 +24,22 @@ stdenv.mkDerivation rec {
     sha256 = "1mr46raha5aqi8ba0cqvyil5z4vcr46hnxqqmpk3fkrr8awd2897";
   };
 
-  passthru.updateScript = ./update.sh;
-
   # don't remove runtime deps
   dontPatchELF = true;
 
   nativeBuildInputs = [ autoPatchelfHook wrapGAppsHook unzip ];
 
   buildInputs = with xorg; [
-    libXScrnSaver libXdamage libXtst libxshmfence
+    libXScrnSaver
+    libXdamage
+    libXtst
+    libxshmfence
   ] ++ [
-    nss gtk2 alsa-lib gnome2.GConf gtk3
+    nss
+    gtk2
+    alsa-lib
+    gnome2.GConf
+    gtk3
     mesa # for libgbm
   ];
 
@@ -41,11 +61,19 @@ stdenv.mkDerivation rec {
     runHook postInstall
   '';
 
+  passthru = {
+    updateScript = ./update.sh;
+
+    tests = {
+      example = callPackage ./cypress-example-kitchensink { };
+    };
+  };
+
   meta = with lib; {
     description = "Fast, easy and reliable testing for anything that runs in a browser";
     homepage = "https://www.cypress.io";
     license = licenses.mit;
-    platforms = ["x86_64-linux"];
+    platforms = [ "x86_64-linux" ];
     maintainers = with maintainers; [ tweber mmahut ];
   };
 }