in Practice Scala patric.fornasier@thoughtworks.com - - PowerPoint PPT Presentation

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in Practice Scala patric.fornasier@thoughtworks.com - - PowerPoint PPT Presentation

Mar 29, 2023 148 likes •969 views

in Practice Scala patric.fornasier@thoughtworks.com marc.hofer@thoughtworks.com e c n e i r e p x E Optimising IT n g i s e D Organisations Consulting Build & Release Management technology esting T Offices 2 Warning

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inPractice

Scala

patric.fornasier@thoughtworks.com marc.hofer@thoughtworks.com

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Optimising IT Organisations technology

Consulting

T esting Build & Release Management E x p e r i e n c e D e s i g n

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Offices

2

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presentation Contains code examples

Warning

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Context

A bit of about the project

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?

Why Scala

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What is Scala ?

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Scala

Functional Object Oriented Statically Typed Scriptable JVM- based

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JVM Byte Code Compile Scala

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Benefits

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“Functional Programming”

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List<String> features = Arrays.asList("noFeature", "featureC", "featureB", "featureA"); for (String feature : features) { System.out.println(feature); }

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List<String> javaFeatures = Arrays.asList("noFeature", "featureC", "featureB", "featureA"); for (String feature : javaFeatures) { System.out.println(feature); } val scalaFeatures = List( "noFeature", "featureC", "featureB", "featureA") scalaFeatures foreach { println _ }

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val currentFeatures = List("noFeature", "featureC", "featureB", "featureA") Result: "featureA_toggle, featureB_toggle" currentFeatures.filter { _.startsWith("feature") } .mkString(", ") .map { _ + "_toggle" } .sorted .take(2)

?

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String result = ""; List<String> currentFeatures = Arrays.asList("noFeature", "featureC", "featureB", "featureA"); Collections.sort(currentFeatures); int i = 0, j = 0, take = 2; while(i < take && j < currentFeatures.size()) { String feature = currentFeatures.get(j++); if(feature.startsWith("feature")) { result += feature + "_toggle" + ((i++ != take) ? ", " : ""); } } currentFeatures.filter { _.startsWith("feature") } .mkString(", ") .map { _ + "_toggle" } .sorted .take(2)

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“Less Boilerplate”

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public class Property {}

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class Property {}

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public class Property { private final String key; private final String value; private final String defaultValue; public Property(String key, String value, String defaultValue) { this.key = key; this.value = value; this.defaultValue = defaultValue; } }

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class Property(key: String, value: String, default: String) {}

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public class Property { // ... public String getKey() { return key; } public String getValue() { return value; } public String getDefaultValue() { return defaultValue; } }

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class Property(val key: String, val value: String, val default: String) {}

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public class Property { // ... public Property changeTo(String newValue) { return new Property(key, value, newValue); } public Property reset() { return new Property(key, value); } @Override public String toString() { return String.format("%s=%s", key, value); } }

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class Property(val key: String, val value: String, val default: String) { def changeTo(newValue: String) = new Property(key, newValue, default) def reset = new Property(key, default)

  • verride def toString = "%s=%s" format(key, value)

}

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public class Property { // ... @Override public boolean equals(Object obj) { if (!(obj instanceof Property)) return false; Property other = (Property) obj; return other.key.equals(key) && other.value.equals(value) && other.defaultValue.equals(defaultValue) } @Override public int hashCode() { int result = 17; result = 31 * result + key; result = 31 * result + value; result = 31 * result + defaultValue; return result; } }

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case class Property(key: String, value: String, default: String) { def changeTo(newValue: String) = Property(key, newValue, default) def reset = Property(key, default)

  • verride def toString = "%s=%s" format(key, value)

}

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SLIDE 32 public class Property { private final String key; private final String value; private final String defaultValue; public Property(String key, String value, String defaultValue) { this.key = key; this.value = value; this.defaultValue = defaultValue; } public String getKey() { return key; } public String getValue() { return value; } public String getDefaultValue() { return defaultValue; } public Property changeTo(String newValue) { return new Property(key, value, newValue); } public Property reset() { return new Property(key, value); } @Override public String toString() { return String.format("%s=%s", key, value); } @Override public boolean equals(Object obj) { if (!(obj instanceof Property)) return false; Property other = (Property) obj; return other.key.equals(key) && other.value.equals(value) && other.defaultValue.equals(defaultValue) } @Override public int hashCode() { int result = 17; result = 31 * result + key; result = 31 * result + value; result = 31 * result + defaultValue; return result; } }
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case class Property(key: String, value: String, default: String) { def changeTo(newValue: String) = Property(key, newValue, default) def reset = Property(key, default)

  • verride def toString = "%s=%s" format(key, value)

}

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SLIDE 34 public class Property { private final String key; private final String value; private final String defaultValue; public Property(String key, String value, String defaultValue) { this.key = key; this.value = value; this.defaultValue = defaultValue; } public String getKey() { return key; } public String getValue() { return value; } public String getDefaultValue() { return defaultValue; } public Property changeTo(String newValue) { return new Property(key, value, newValue); } public Property reset() { return new Property(key, value); } @Override public boolean equals(Object obj) { if (!(obj instanceof Property)) return false; Property other = (Property) obj; return other.key.equals(key) && other.value.equals(value) && other.defaultValue.equals(defaultValue) } @Override public int hashCode() { int result = 17; result = 31 * result + key; result = 31 * result + value; result = 31 * result + defaultValue; return result; } @Override public String toString() { return String.format("%s=%s", key, value); } } case class Property(key: String, value: String, default: String) { def changeTo(newValue: String) = Property(key, newValue, default) def reset = Property(key, default)
  • verride def toString = "%s=%s" format(key, value)
}

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L O C s

* ignoring blank lines
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Another Example: { Blocks }

“Less Boilerplate”

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val content = get("http://foo.com") { toString } val statusCode = get("http://foo.com") { statusCode } get("http://foo.com") int statusCode = httpSupport.get("http://foo.com", new Block<Integer>() { public Integer execute(HttpResponse response) { return response.getStatusLine().getStatusCode()); } }); String content = httpSupport.get("http://foo.com", new Block<String>() { public Integer execute(HttpResponse response) { return EntityUtils.toString(response.getEntity()); } }); httpSupport.get("http://foo.com", new VoidBlock() { public void execute(HttpResponse response) {} });

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“Java Compatibility”

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java -cp "lib/*" com.springer.core.app.Casper

Scala library goes in here!

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val java = new java.util.ArrayList[String] val scala: Seq[String] = foo filter { ... }

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val log = Logger.getLogger("com.foo") log.debug("Hello!")

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“Gentle Learning Curve”

“Java without ;”

Library re-use

JVM

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<XML-Support/>

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<PdfInfo hasAccess="false">

<DDSId>12345</DDSId> <ContentType>Article</ContentType> </PdfInfo>

val pdfInfo = val contentType = (pdfInfo \ "ContentType").text val hasAccess = (pdfInfo \ "@hasAccess").text.toBoolean

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val pdfInfoList = <PdfInfoList>

<PdfInfo hasAccess="false"> <DDSId>12345</DDSId> <ContentType>Article</ContentType> </PdfInfo> <PdfInfo hasAccess="true"> <DDSId>54321</DDSId> <ContentType>Book</ContentType> </PdfInfo> </PdfInfoList>

case class PdfInfo(xml: NodeSeq) { val ddsId = (xml \ "DDSId").head.text val hasAccess = (xml \ "@hasAccess").head.text val contentType = (xml \ "ContentType").head.text } (pdfInfoList \ "PdfInfo") map { PdfInfo(_) }

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“DSL- Friendly”

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System App2 App3 Functional App1 Unit DB Integration

Levels of Testing

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Unit Test DSL

class PropertyTest extends Spec with ShouldMatchers { it("should render key and value separated with an equals sign") { Property("shark", "fish").toString should equal ("shark=fish") } }

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class ForgottenPasswordPageTests extends FunctionalTestSpec with ForgottenPasswordSteps with Uris { it("should validate user email") { given(iNavigateTo(ForgottenPasswordPage)) when(iSubmitEmail("invalid@email.com")) then(iShouldSeeInvalidEmailErrorMessage) } }

Functional Test DSL

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Document Validation DSL

trait DDSValidationRules extends JournalXPaths with APlusPlusElements { val journalRules = List( No(JournalTitle) is Invalid, MoreThanOneElementIn(JournalArticle) is Invalid, BadLanguageIn(JournalArticleLanguage) is Invalid, JournalIssue With No(JournalIssueCoverYear) is Invalid, Bibliography With No(BibliographyHeading) is Invalid, MarkupIn(JournalTitle) is Unsupported, MarkupIn(JournalAuthor) is Unsupported ) }

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“Active Community”

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“Fun”

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“Fun”

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“Fun”

val foo = (7 to 21)

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“Fun”

List<Integers> foo = new ArrayList<Integers>() for (int i = 7; i <= 21; i++) { foo.add(i); }

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“Fun”

def eat(food: String = "plankton")

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“Fun”

public void eat(String food) {...} public void eat() { eat("plankton"); }

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get("http://foo.com") { statusCode }

“Fun”

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httpSupport.get("http://foo.com", new Block<Integer>() { public Integer execute(HttpResponse response) { return response.getStatusLine().getStatusCode()); } });

“Fun”

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Drawbacks

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“Tool Support”

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! ?

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1 : 1

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“More rope...”

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Scala Collection Library

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class JournalPageTests extends Spec with FunctionalTestSpec with JournalPageSteps with SearchResultsPageSteps with LanguageSteps with LanguageSupport with JavascriptSupport with Uris with IssuePageSteps with VolumesAndIssuesPageSteps with CoverImageUrlBuilders with FakeEntitlementSteps with FullTextPageSteps with CommonAbstractSteps with GoogleAnalyticsSteps with ActionSectionSteps { ... }

Traits Galore in our codebase...

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xsbt

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scalaz

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→

Can Should

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Risk Mitigations

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Would we do it again

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disclaimer

use scala at your own risk

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Thanks

for

Listening

@patforna | @mhoefi