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Merge pull request #20 from ministryofjustice/story/ccmspui-424-create-reusable-component
CCMSPUI-424 | Add govuk-dialect spring boot starter
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‎laa-ccms-spring-boot-starters/laa-ccms-spring-boot-starter-govuk-dialect/build.gradle

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plugins {
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id 'spring-boot-starter-conventions'
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id 'checkstyle'
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}
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dependencies {
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api("org.thymeleaf:thymeleaf-spring6")
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}
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checkstyle {
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maxWarnings = 0
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toolVersion = checkstyleVersion
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sourceSets = sourceSets.main as SourceSetContainer
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showViolations = true
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}
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publishing.publications {
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library(MavenPublication) {
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from components.java
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}
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}
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test {
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useJUnitPlatform()
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}

‎laa-ccms-spring-boot-starters/laa-ccms-spring-boot-starter-govuk-dialect/src/main/java/uk/gov/laa/ccms/springboot/dialect/ButtonElementTagProcessor.java

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package uk.gov.laa.ccms.springboot.dialect;
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import java.util.HashMap;
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import java.util.Map;
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import java.util.regex.Pattern;
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import org.apache.logging.log4j.util.Strings;
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import org.thymeleaf.context.ITemplateContext;
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import org.thymeleaf.model.IModel;
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import org.thymeleaf.model.IModelFactory;
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import org.thymeleaf.model.IProcessableElementTag;
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import org.thymeleaf.processor.element.AbstractElementTagProcessor;
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import org.thymeleaf.processor.element.IElementTagStructureHandler;
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import org.thymeleaf.standard.expression.IStandardExpression;
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import org.thymeleaf.standard.expression.IStandardExpressionParser;
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import org.thymeleaf.standard.expression.StandardExpressions;
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import org.thymeleaf.templatemode.TemplateMode;
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/**
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* Transforms <govuk:button/> elements into standard HTML button elements.
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*/
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public class ButtonElementTagProcessor extends AbstractElementTagProcessor {
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private static final String TAG_NAME = "button";
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private static final int PRECEDENCE = 900;
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private static final Pattern CLEANER = Pattern.compile("(?m)^[ \t]*\r?\n");
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public ButtonElementTagProcessor() {
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super(TemplateMode.HTML, "govuk", TAG_NAME, true, null, false, PRECEDENCE);
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}
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@Override
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protected void doProcess(ITemplateContext context, IProcessableElementTag tag,
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IElementTagStructureHandler structureHandler) {
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Map<String, String> attributes = parseAttributes(context, tag);
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String classNames = buildClassNames(attributes);
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String commonAttributes = buildCommonAttributes(classNames, attributes);
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String buttonAttributes = buildButtonAttributes(attributes);
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String html = attributes.containsKey("href") ? buildAnchorHtml(attributes, commonAttributes) :
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buildButtonHtml(attributes, commonAttributes, buttonAttributes);
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replaceElementWithHtml(context, structureHandler, html);
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}
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private Map<String, String> parseAttributes(ITemplateContext context,
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IProcessableElementTag tag) {
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Map<String, String> attributes = tag.getAttributeMap();
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Map<String, String> resolvedAttributes = new HashMap<>();
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IStandardExpressionParser parser =
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StandardExpressions.getExpressionParser(context.getConfiguration());
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for (Map.Entry<String, String> entry : attributes.entrySet()) {
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String key = entry.getKey();
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String value = entry.getValue();
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if (key.startsWith("th:")) {
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IStandardExpression expression = parser.parseExpression(context, value);
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resolvedAttributes.put(key.replace("th:", ""), (String) expression.execute(context));
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} else {
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resolvedAttributes.put(key, value);
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}
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}
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return resolvedAttributes;
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}
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private String buildClassNames(Map<String, String> attributes) {
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String classNames = "govuk-button";
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if (attributes.containsKey("classes")) {
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classNames += " " + attributes.get("classes");
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}
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return classNames;
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}
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private String buildCommonAttributes(String classNames, Map<String, String> attributes) {
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StringBuilder commonAttributes = new StringBuilder();
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commonAttributes.append("class=\"").append(classNames)
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.append("\" data-module=\"govuk-button\"");
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if (attributes.containsKey("id")) {
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commonAttributes.append(" id=\"").append(attributes.get("id")).append("\"");
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}
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return commonAttributes.toString();
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}
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private String buildButtonAttributes(Map<String, String> attributes) {
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StringBuilder buttonAttributes = new StringBuilder();
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if (attributes.containsKey("name")) {
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buttonAttributes.append(" name=\"").append(attributes.get("name")).append("\"");
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}
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if (attributes.containsKey("disabled")) {
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buttonAttributes.append(" disabled aria-disabled=\"true\"");
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}
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if (attributes.containsKey("preventDoubleClick")) {
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buttonAttributes.append(" data-prevent-double-click=\"")
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.append(attributes.get("preventDoubleClick")).append("\"");
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}
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return buttonAttributes.toString();
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}
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private String buildAnchorHtml(Map<String, String> attributes, String commonAttributes) {
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return "<a href=\"" + attributes.getOrDefault("href", "#")
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+ "\" role=\"button\" draggable=\"false\" " + commonAttributes + ">"
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+ attributes.getOrDefault("text", "") + "</a>";
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}
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private String buildButtonHtml(Map<String, String> attributes, String commonAttributes,
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String buttonAttributes) {
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return "<button type=\"" + attributes.getOrDefault("type", "submit") + "\" "
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+ buttonAttributes + " " + commonAttributes + ">" + attributes.getOrDefault("text", "")
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+ "</button>";
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}
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private void replaceElementWithHtml(ITemplateContext context,
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IElementTagStructureHandler structureHandler, String html) {
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final String adjusted = CLEANER.matcher(html).replaceAll(Strings.EMPTY);
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final IModelFactory modelFactory = context.getModelFactory();
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final IModel model = modelFactory.parse(context.getTemplateData(), adjusted);
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structureHandler.replaceWith(model, false);
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}
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}
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‎laa-ccms-spring-boot-starters/laa-ccms-spring-boot-starter-govuk-dialect/src/main/java/uk/gov/laa/ccms/springboot/dialect/GovUkDialect.java

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package uk.gov.laa.ccms.springboot.dialect;
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import java.util.Set;
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import org.thymeleaf.dialect.AbstractProcessorDialect;
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import org.thymeleaf.processor.IProcessor;
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import org.thymeleaf.standard.StandardDialect;
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/**
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* Develops a custom GOV.UK dialect.
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*/
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public class GovUkDialect extends AbstractProcessorDialect {
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private static final String DIALECT_NAME = "GovUKDialect";
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public GovUkDialect() {
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super(DIALECT_NAME, "govuk", StandardDialect.PROCESSOR_PRECEDENCE);
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}
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@Override
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public Set<IProcessor> getProcessors(String dialectPrefix) {
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return Set.of(new ButtonElementTagProcessor());
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}
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}

‎laa-ccms-spring-boot-starters/laa-ccms-spring-boot-starter-govuk-dialect/src/main/java/uk/gov/laa/ccms/springboot/dialect/GovUkThymeleafDialectConfig.java

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package uk.gov.laa.ccms.springboot.dialect;
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import org.springframework.boot.autoconfigure.AutoConfiguration;
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import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
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import org.springframework.context.annotation.Bean;
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import org.thymeleaf.spring6.SpringTemplateEngine;
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/**
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* Custom ThymeleafDialectConfig.
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*/
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@AutoConfiguration
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@ConditionalOnClass(SpringTemplateEngine.class)
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public class GovUkThymeleafDialectConfig {
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/**
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* SpringTemplateEngine with custom dialect.
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*/
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@Bean
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public GovUkDialect govUkDialect() {
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return new GovUkDialect();
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}
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}

‎laa-ccms-spring-boot-starters/laa-ccms-spring-boot-starter-govuk-dialect/src/main/resources/META-INF/spring/org.springframework.boot.autoconfigure.AutoConfiguration.imports

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uk.gov.laa.ccms.springboot.dialect.GovUkThymeleafDialectConfig

‎laa-ccms-spring-boot-starters/laa-ccms-spring-boot-starter-govuk-dialect/src/test/java/uk/gov/laa/ccms/springboot/dialect/ButtonElementTagProcessorTest.java

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package uk.gov.laa.ccms.springboot.dialect;
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import static org.assertj.core.api.Assertions.assertThat;
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import org.junit.jupiter.api.Test;
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import org.springframework.beans.factory.annotation.Autowired;
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import org.springframework.boot.test.context.SpringBootTest;
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import org.thymeleaf.context.Context;
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import org.thymeleaf.spring6.SpringTemplateEngine;
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@SpringBootTest(classes = ThymeleafTestConfig.class)
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class ButtonElementTagProcessorTest {
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@Autowired
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private SpringTemplateEngine templateEngine;
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@Test
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void shouldRenderGovukButton() {
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Context context = new Context();
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String renderedHtml = templateEngine.process("test-button", context);
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assertThat(renderedHtml)
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.contains("<a href=\"/test\" role=\"button\" draggable=\"false\" class=\"govuk-button custom-class\" data-module=\"govuk-button\" id=\"button-id\">Click Me!</a>")
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.contains("<button type=\"submit\" disabled aria-disabled=\"true\" class=\"govuk-button\" data-module=\"govuk-button\" id=\"button-id\">Click Me!</button>");
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}
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}

‎laa-ccms-spring-boot-starters/laa-ccms-spring-boot-starter-govuk-dialect/src/test/java/uk/gov/laa/ccms/springboot/dialect/ThymeleafTestConfig.java

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package uk.gov.laa.ccms.springboot.dialect;
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import org.springframework.context.annotation.Bean;
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import org.springframework.context.annotation.Configuration;
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import org.thymeleaf.spring6.SpringTemplateEngine;
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import org.thymeleaf.spring6.templateresolver.SpringResourceTemplateResolver;
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import org.thymeleaf.templatemode.TemplateMode;
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@Configuration
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public class ThymeleafTestConfig {
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@Bean
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public SpringTemplateEngine testTemplateEngine() {
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SpringTemplateEngine templateEngine = new SpringTemplateEngine();
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templateEngine.addDialect(new GovUkDialect());
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templateEngine.addTemplateResolver(templateResolver());
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return templateEngine;
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}
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@Bean
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public SpringResourceTemplateResolver templateResolver() {
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SpringResourceTemplateResolver resolver = new SpringResourceTemplateResolver();
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resolver.setPrefix("classpath:/templates/");
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resolver.setSuffix(".html");
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resolver.setTemplateMode(TemplateMode.HTML);
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resolver.setCacheable(false);
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return resolver;
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}
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}

‎laa-ccms-spring-boot-starters/laa-ccms-spring-boot-starter-govuk-dialect/src/test/resources/templates/test-button.html

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<!DOCTYPE html>
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<html xmlns:govuk="http://www.thymeleaf.org" lang="EN">
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<head>
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<title>Button Test</title>
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</head>
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<body>
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<govuk:button th:text="'Click Me!'" href="/test" id="button-id" classes="custom-class"/>
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<govuk:button th:text="'Click Me!'" id="button-id" disabled/>
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</body>
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</html>

‎settings.gradle

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include ':laa-ccms-java-gradle-plugin'
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include ':laa-ccms-spring-boot-starters'
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include ':laa-ccms-spring-boot-starters:laa-ccms-spring-boot-starter-auth'
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include ':laa-ccms-spring-boot-starters:laa-ccms-spring-boot-starter-govuk-dialect'

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