Deprecate old yarn versions (#520)

Yarn versions lower than 0.19 will crash if passed --frozen-lockfile, but usage of these versions has dropped to near-zero.

bin/compile

@@ -41,6 +41,7 @@ echo "" > "$LOG_FILE"
 
 handle_failure() {
   header "Build failed"
+  fail_yarn_outdated "$LOG_FILE"
   fail_yarn_lockfile_outdated "$LOG_FILE"
   fail_node_install "$LOG_FILE"
   fail_yarn_install "$LOG_FILE"

lib/dependencies.sh

@@ -85,27 +85,12 @@ log_build_scripts() {
   fi
 }
 
-yarn_supports_frozen_lockfile() {
-  local yarn_version="$(yarn --version)"
-  # Yarn versions lower than 0.19 will crash if passed --frozen-lockfile
-  if [[ "$yarn_version" =~ ^0\.(16|17|18).*$ ]]; then
-    mcount "yarn.doesnt-support-frozen-lockfile"
-    false
-  else
-    true
-  fi
-}
-
 yarn_node_modules() {
   local build_dir=${1:-}
 
   echo "Installing node modules (yarn.lock)"
   cd "$build_dir"
-  if yarn_supports_frozen_lockfile; then
-    yarn install --frozen-lockfile --ignore-engines 2>&1
-  else
-    yarn install --pure-lockfile --ignore-engines 2>&1
-  fi
+  yarn install --frozen-lockfile --ignore-engines 2>&1
 }
 
 npm_node_modules() {

lib/failure.sh

@@ -118,6 +118,29 @@ fail_multiple_lockfiles() {
   fi
 }
 
+fail_yarn_outdated() {
+  local log_file="$1"
+  local yarn_engine=$(read_json "$BUILD_DIR/package.json" ".engines.yarn")
+
+  if grep -qi 'error: unknown option .--frozen-lockfile' "$log_file"; then
+    echo "ran"
+    mcount "failures.outdated-yarn"
+    echo ""
+    warn "Outdated Yarn version: $yarn_engine
+
+       Your application is specifying a requirement on an old version of Yarn ($yarn_engine)
+       which does not support the --frozen-lockfile option. Please upgrade to a
+       newer version, at least 0.19, by updating your requirement in the 'engines'
+       field in your package.json.
+
+       \"engines\": {
+         \"yarn\": \"1.3.2\"
+       }
+    " https://devcenter.heroku.com/articles/nodejs-support#specifying-a-yarn-version
+    exit 1
+  fi
+}
+
 fail_yarn_lockfile_outdated() {
   local log_file="$1"
   if grep -qi 'Your lockfile needs to be updated' "$log_file"; then
@@ -204,7 +227,7 @@ fail_yarn_install() {
     echo ""
     warn "No matching version found for Yarn: $yarn_engine
 
-       Heroku supports every version of Yarn published on npm, however you have
+       Heroku supports most versions of Yarn published on npm, however you have
        specified a version in package.json ($yarn_engine) that does not correspond
        to any published version of Yarn. You can see a list of all published
        versions of Yarn with the following command:

test/fixtures/yarn-engine/package.json

@@ -4,7 +4,7 @@
   "main": "index.js",
   "license": "MIT",
   "engines": {
-    "yarn": "0.16.1"
+    "yarn": "1.4.0"
   },
   "dependencies": {
     "lodash": "^4.16.4"

test/fixtures/yarn-old-deprecated-version/package.json

+{
+  "name": "yarn",
+  "version": "1.0.0",
+  "main": "index.js",
+  "license": "MIT",
+  "engines": {
+    "yarn": "~0.16"
+  },
+  "dependencies": {
+    "lodash": "^4.16.4"
+  }
+}

test/fixtures/yarn-old-deprecated-version/yarn.lock

+# THIS IS AN AUTOGENERATED FILE. DO NOT EDIT THIS FILE DIRECTLY.
+# yarn lockfile v1
+lodash:
+  version "4.16.4"
+  resolved "https://registry.yarnpkg.com/lodash/-/lodash-4.16.4.tgz#01ce306b9bad1319f2a5528674f88297aeb70127"
+

test/fixtures/yarn-only-engine/package.json

@@ -4,7 +4,7 @@
   "main": "index.js",
   "license": "MIT",
   "engines": {
-    "yarn": "0.24.5"
+    "yarn": "1.4.0"
   },
   "dependencies": {
     "lodash": "^4.16.4"

test/fixtures/yarn-semver/package.json

@@ -4,7 +4,7 @@
   "main": "index.js",
   "license": "MIT",
   "engines": {
-    "yarn": "~0.17"
+    "yarn": "~0.28"
   },
   "dependencies": {
     "lodash": "^4.16.4"

test/run

@@ -116,11 +116,22 @@ testCacheWithPrebuild() {
 
 testYarnSemver() {
   compile "yarn-semver"
-  assertCaptured "Resolving yarn version ~0.17"
-  assertCaptured "installing yarn (0.17."
+  assertCaptured "Resolving yarn version ~0.28"
+  assertCaptured "installing yarn (0.28."
   assertCapturedSuccess
 }
 
+testOldYarn() {
+  compile "yarn-old-deprecated-version"
+  assertCaptured "Resolving yarn version ~0.16"
+  assertCaptured "installing yarn (0.16."
+  assertCaptured "error: unknown option \`--frozen-lockfile'"
+  assertCaptured "Outdated Yarn version"
+  assertCaptured "Your application is specifying a requirement on an old version of Yarn"
+  assertCaptured "https://devcenter.heroku.com/articles/nodejs-support#specifying-a-yarn-version"
+  assertCapturedError
+}
+
 testYarnInvalid() {
   compile "yarn-invalid"
   assertCaptured "Resolving yarn version 0.171"
@@ -148,7 +159,7 @@ testYarnRun() {
 
 testYarnEngine() {
   compile "yarn-engine"
-  assertCaptured "installing yarn (0.16.1)"
+  assertCaptured "installing yarn (1.4.0)"
   assertCapturedSuccess
 }
 
@@ -157,7 +168,7 @@ testYarnEngine() {
 # though we will only install using yarn if a yarn.lock exists
 testYarnOnlyEngine() {
   compile "yarn-only-engine"
-  assertCaptured "installing yarn (0.24.5)"
+  assertCaptured "installing yarn (1.4.0)"
   assertCapturedSuccess
 }