Scala Boilerplate

Assortment of default settings, best practices, and general goodies for Scala projects.

Scala REPL

The console and consoleQuick sbt tasks start the Scala REPL with a few commonly used imports such as JavaConverters, collection.mutable, Future, Random, Try and NonFatal already in scope.

The REPL also defines a desugar macro, that expands an expression to its desugared form and inferred type. Try, for instance desugar(1 to 3).

Database migration

To run database migrations, use the flywayMigrate sbt tasks.

Migration files are stored in the src/resources/db/migration/ folder. Filenames follow the convention nnnn.pp__desc.sql (for instance, 0001__create_user.sql) where:

nnnn is the version: a unique, leading zero-padded, strictly increasing numeric sequence
.pp is an optional patch number: same rules as above, used only by hotfixes
desc is a brief description written in lower_case_underscore

Down (reverse) migrations

While Flyway doesn't support down migrations, by convention we put the SQL DDL commands to reverse the migration as a comment at the bottom of the file:

create table if not exists user;

-- down
/*
drop table if exists user;
*/

Scalastyle

The scalastyle and test:scalastyle sbt tasks are used to check source and test code with Scalastyle. The error list is saved to Checkstyle-compatible files target/scalastyle-result.xml and target/scalastyle-test-result.xml respectively.

Scalastyle runs automatically against source and test code with the sbt test task.

It is not recommended to make the compile task dependent on Scalastyle. Since Scalastyle runs first and fails if the code does not compile, one would not get the Scala compiler error messages.

scoverage

To execute tests with code coverage enabled run the following sbt tasks: clean coverage test coverageReport. Coverage reports are saved to target/scala-2.11/scoverage-report/.

The coverage command is sticky. To turn it off, use coverageOff.

Scalariform

To format source and test code run the scalariformFormat and test:scalariformFormat sbt tasks.

Scalariform is provided as a convenience and starting point; it is not sufficient to be fully compliant with the Scala Style Guide.

sbt-updates

There is a dependencyUpdates sbt task to check Maven repositories for dependency updates.

sbt-license-report

To generate a report with the dependency licenses used by the project, use the dumpLicenseReport sbt task. The report is saved to the target/license-reports directory.

sbt-dependency-graph

This plugin adds three main tasks: dependency-tree displays the project dependencies as a tree, dependency-graph shows it as a graph, and what-depends-on <organization> <module> <revision> shows everything that depends on an artifact.

sbt-stats

The stats sbt task shows basic line counting statistics.

sbteclipse

Uncomment the related line in project/plugins.sbt to enable the eclipse sbt task to create Eclipse project definitions.

License

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

jxie418/scala-boilerplate