feature: WIP: Subject code generator, fixes #612

core/pom.xml

@@ -124,6 +124,11 @@
               </excludes>
             </configuration>
           </execution>
+          <execution>
+            <goals>
+              <goal>test-jar</goal>
+            </goals>
+          </execution>
         </executions>
       </plugin>
       <plugin>

extensions/generator/pom.xml

@@ -0,0 +1,121 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <parent>
+        <groupId>com.google.truth.extensions</groupId>
+        <artifactId>truth-extensions-parent</artifactId>
+        <version>HEAD-SNAPSHOT</version>
+    </parent>
+    <modelVersion>4.0.0</modelVersion>
+
+    <name>Truth Extension for generating Subjects</name>
+    <artifactId>truth-generator-extension</artifactId>
+
+    <properties>
+        <version.roaster>2.23.0.Final</version.roaster>
+    </properties>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.jboss.forge.roaster</groupId>
+            <artifactId>roaster-api</artifactId>
+            <version>${version.roaster}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.jboss.forge.roaster</groupId>
+            <artifactId>roaster-jdt</artifactId>
+            <version>${version.roaster}</version>
+            <scope>compile</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.google.truth</groupId>
+            <artifactId>truth</artifactId>
+            <scope>compile</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.google.truth</groupId>
+            <artifactId>truth</artifactId>
+            <type>test-jar</type>
+            <version>HEAD-SNAPSHOT</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.checkerframework</groupId>
+            <artifactId>checker-compat-qual</artifactId>
+            <version>2.5.5</version>
+        </dependency>
+        <dependency>
+            <groupId>org.atteo</groupId>
+            <artifactId>evo-inflector</artifactId>
+            <version>1.3</version>
+        </dependency>
+        <dependency>
+            <groupId>org.reflections</groupId>
+            <artifactId>reflections</artifactId>
+            <version>0.9.12</version>
+        </dependency>
+        <!-- reflections optional dependency -->
+        <dependency>
+            <groupId>org.dom4j</groupId>
+            <artifactId>dom4j</artifactId>
+            <version>2.1.1</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-lang3</artifactId>
+            <version>3.12.0</version>
+        </dependency>
+        <dependency>
+            <groupId>com.google.guava</groupId>
+            <artifactId>guava</artifactId>
+            <version>30.1.1-android</version>
+        </dependency>
+        <dependency>
+            <groupId>com.google.flogger</groupId>
+            <artifactId>flogger</artifactId>
+            <version>0.6</version>
+        </dependency>
+        <dependency>
+            <groupId>com.google.flogger</groupId>
+            <artifactId>flogger-log4j2-backend</artifactId>
+            <version>0.6</version>
+        </dependency>
+        <dependency>
+            <groupId>com.google.flogger</groupId>
+            <artifactId>flogger-system-backend</artifactId>
+            <version>0.6</version>
+        </dependency>
+        <dependency>
+            <groupId>org.projectlombok</groupId>
+            <artifactId>lombok</artifactId>
+            <version>1.18.20</version>
+        </dependency>
+        <dependency>
+            <groupId>uk.co.jemos.podam</groupId>
+            <artifactId>podam</artifactId>
+            <version>7.2.7.RELEASE</version>
+            <scope>compile</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <configuration>
+                    <source>1.8</source>
+                    <target>1.8</target>
+                </configuration>
+            </plugin>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <configuration>
+                    <source>13</source>
+                    <target>13</target>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+</project>

extensions/generator/src/main/java/com/google/common/truth/extension/generator/SourceClassSets.java

@@ -0,0 +1,106 @@
+package com.google.common.truth.extension.generator;
+
+import com.google.common.collect.ImmutableListMultimap;
+import com.google.common.collect.Multimaps;
+import lombok.Getter;
+import lombok.Value;
+
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.Set;
+import java.util.stream.Collectors;
+
+/**
+ * Use this class to prepare the set of source classes to generate for, and settings for different types of sources.
+ */
+@Getter
+public class SourceClassSets {
+
+  private final String packageForOverall;
+  private final Set<Class<?>[]> simplePackageOfClasses = new HashSet<>();
+  private final Set<Class<?>> simpleClasses = new HashSet<>();
+  private final Set<PackageAndClasses> packageAndClasses = new HashSet<>();
+  private final Set<Class<?>> legacyBeans = new HashSet<>();
+  private final Set<PackageAndClasses> legacyPackageAndClasses = new HashSet<>();
+
+
+  /**
+   * @param packageForOverall the package to put the overall access points
+   */
+  public SourceClassSets(final String packageForOverall) {
+    this.packageForOverall = packageForOverall;
+  }
+
+  /**
+   * Use the package of the parameter as the base package;
+   */
+  public SourceClassSets(Object packageFromObject) {
+    this(packageFromObject.getClass().getPackage().getName());
+  }
+
+  public SourceClassSets(Class<?> packageFromClass) {
+    this(packageFromClass.getPackage().getName());
+  }
+
+  public void generateAllFoundInPackagesOf(Class<?>... classes) {
+    simplePackageOfClasses.add(classes);
+  }
+
+  /**
+   * Useful for generating Java module Subjects and put them in our package.
+   * <p>
+   * I.e. for UUID.class you can't create a Subject in the same package as it (not allowed).
+   */
+  public void generateFrom(String targetPackageName, Class<?>... classes) {
+    packageAndClasses.add(new PackageAndClasses(targetPackageName, classes));
+  }
+
+  public void generateFrom(Class<?>... classes) {
+    this.simpleClasses.addAll(Arrays.stream(classes).collect(Collectors.toSet()));
+  }
+
+  public void generateFrom(Set<Class<?>> classes) {
+    this.simpleClasses.addAll(classes);
+  }
+
+  /**
+   * Shades the given source classes into the base package, suffixed with the source package
+   */
+  public void generateFromShaded(Class<?>... classes) {
+    Set<PackageAndClasses> packageAndClassesStream = mapToPackageSets(classes);
+    this.packageAndClasses.addAll(packageAndClassesStream);
+  }
+
+  private Set<PackageAndClasses> mapToPackageSets(Class<?>[] classes) {
+    ImmutableListMultimap<Package, Class<?>> grouped = Multimaps.index(Arrays.asList(classes), Class::getPackage);
+
+    return grouped.keySet().stream().map(x -> {
+      Class<?>[] classSet = grouped.get(x).toArray(new Class<?>[0]);
+      PackageAndClasses newSet = new PackageAndClasses(getTargetPackageName(x),
+              classSet);
+      return newSet;
+    }).collect(Collectors.toSet());
+  }
+
+  private String getTargetPackageName(Package p) {
+    return this.packageForOverall + ".shaded." + p.getName();
+  }
+
+  public void generateFromNonBean(Class<?>... nonBeanLegacyClass) {
+    for (Class<?> beanLegacyClass : nonBeanLegacyClass) {
+      legacyBeans.add(beanLegacyClass);
+    }
+  }
+
+  public void generateFromShadedNonBean(Class<?>... clazzes) {
+    Set<PackageAndClasses> packageAndClassesStream = mapToPackageSets(clazzes);
+    this.legacyPackageAndClasses.addAll(packageAndClassesStream);
+  }
+
+  @Value
+  public static class PackageAndClasses {
+    String targetPackageName;
+    Class<?>[] classes;
+  }
+
+}

extensions/generator/src/main/java/com/google/common/truth/extension/generator/TruthGeneratorAPI.java

@@ -0,0 +1,69 @@
+package com.google.common.truth.extension.generator;
+
+import com.google.common.truth.extension.generator.internal.TruthGenerator;
+import com.google.common.truth.extension.generator.internal.model.ThreeSystem;
+
+import java.util.Map;
+import java.util.Set;
+
+/**
+ *
+ */
+public interface TruthGeneratorAPI {
+
+  static TruthGeneratorAPI create() {
+    return new TruthGenerator();
+  }
+
+  /**
+   * Takes a user maintained source file, and adds boiler plate and Subject methods that are missing. If aggressively
+   * skips parts if it thinks the user has overridden something.
+   * <p>
+   * Not implemented yet.
+   */
+  String maintain(Class source, Class userAndGeneratedMix);
+
+  /**
+   * todo
+   */
+  <T> String combinedSystem(Class<T> source);
+
+  /**
+   * todo
+   */
+  void combinedSystem(String... modelPackages);
+
+  /**
+   * @param modelPackages
+   */
+  void generate(String... modelPackages);
+
+  /**
+   * @param classes
+   */
+  void generateFromPackagesOf(Class<?>... classes);
+
+  /**
+   * @param ss
+   */
+  void combinedSystem(SourceClassSets ss);
+
+  /**
+   * Use this entry point to generate for a large and differing set of source classes - which will also generate a
+   * single point of entry for all of them.
+   *
+   * <p>
+   * There are many different ways to add, check out the different methods in {@link SourceClassSets}.
+   *
+   * @see SourceClassSets
+   */
+  Map<Class<?>, ThreeSystem> generate(SourceClassSets ss);
+
+  /**
+   * @param classes
+   * @return
+   */
+  Map<Class<?>, ThreeSystem> generate(Set<Class<?>> classes);
+
+  void generate(Class<?>... classes);
+}

extensions/generator/src/main/java/com/google/common/truth/extension/generator/UserManagedTruth.java

@@ -0,0 +1,23 @@
+package com.google.common.truth.extension.generator;
+
+import com.google.common.truth.Subject;
+import com.google.common.truth.extension.generator.internal.SkeletonGeneratorAPI;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Target;
+
+/**
+ * Maker for the {@link SkeletonGeneratorAPI#threeLayerSystem)} which instructs the system that this class is the user
+ * managed middle class.
+ * <p>
+ * <p>
+ * Useful for detecting with it already exists, instead of relaying on class name matching. And good for discovering the
+ * class under test.
+ */
+@Target({ElementType.TYPE})
+public @interface UserManagedTruth {
+  /**
+   * The class that this is a {@link Subject} for.
+   */
+  Class<?> clazz();
+}

extensions/generator/src/main/java/com/google/common/truth/extension/generator/internal/MyStringSubject.java

@@ -0,0 +1,63 @@
+package com.google.common.truth.extension.generator.internal;
+
+import com.google.common.truth.FailureMetadata;
+import com.google.common.truth.StringSubject;
+import lombok.AccessLevel;
+import lombok.NoArgsConstructor;
+import org.jboss.forge.roaster.model.source.JavaClassSource;
+
+/**
+ * @see IgnoringWhiteSpaceComparison
+ */
+public class MyStringSubject extends StringSubject {
+
+  String actual;
+
+  protected MyStringSubject(FailureMetadata failureMetadata, String actual) {
+    super(failureMetadata, actual);
+    this.actual = actual;
+  }
+
+  /**
+   * Returns an assertion builder for a {@link JavaClassSource} class.
+   */
+  public static Factory<MyStringSubject, String> myStrings() {
+    return MyStringSubject::new;
+  }
+
+  public IgnoringWhiteSpaceComparison ignoringWhiteSpace() {
+    return new IgnoringWhiteSpaceComparison();
+  }
+
+  @NoArgsConstructor(access = AccessLevel.PRIVATE)
+  public class IgnoringWhiteSpaceComparison {
+
+    public void equalTo(String expected) {
+      String expectedNormal = normalise(expected);
+      String actualNormal = normalise(actual);
+
+      check("").that(actualNormal).isEqualTo(expectedNormal);
+    }
+
+    private String normalise(String raw) {
+      String normal = normaliseEndingsEndings(raw);
+      normal = normaliseWhiteSpaceAtEndings(normal);
+      return normal;
+    }
+
+    /**
+     * lazy remove trailing whitespace on lines
+     */
+    private String normaliseWhiteSpaceAtEndings(String raw) {
+      return raw.replaceAll("(?m)\\s+$", "");
+    }
+
+    /**
+     * make line endings consistent
+     */
+    private String normaliseEndingsEndings(String raw) {
+      return raw.replaceAll("\\r\\n?", "\n");
+    }
+  }
+
+}