Allow passing overwrite behavior through the GemInstaller

build.gradle

@@ -39,7 +39,7 @@ dependencies {
     /* Used for FileUtils and deleting integration test dirs */
     testCompile 'org.apache.commons:commons-io:1.3.2'
     testCompile "org.spockframework:spock-core:1.0-groovy-2.4"
-    testCompile 'org.apache.commons:commons-io:1.3.2+'
+    testCompile 'cglib:cglib-nodep:3.1'
 }
 
 test {

src/main/java/com/github/jrubygradle/jem/GemInstaller.java

@@ -14,22 +14,64 @@ public class GemInstaller {
         FAIL
     };
 
-
     protected com.github.jrubygradle.jem.internal.GemInstaller impl;
 
+    /**
+     * Create an installer with the given installation directory and a single gem
+     *
+     * @param installDir
+     * @param gemPath
+     */
     public GemInstaller(String installDir, String gemPath) {
         this(installDir, new File(gemPath));
     }
 
+    /**
+     * Create an installer with the given installation directory and a single gem
+     *
+     * @param installDir
+     * @param gemFile
+     */
     public GemInstaller(String installDir, File gemFile) {
         this(installDir, Arrays.asList(gemFile));
     }
 
+    /**
+     * Create an installer with the given installation directory and a list of gems
+     *
+     * @param installDir
+     * @param gemPaths
+     */
     public GemInstaller(String installDir, List<File> gemPaths) {
         impl = new com.github.jrubygradle.jem.internal.GemInstaller(installDir, gemPaths);
     }
 
+    /**
+     * Inject a custom GemInstaller implementation that adheres to the private internal API.
+     *
+     * Chances are you do not want this constructor, which is largely used for unit testing!
+     *
+     * @param implementation
+     */
+    public GemInstaller(com.github.jrubygradle.jem.internal.GemInstaller implementation) {
+        impl = implementation;
+    }
+
+    /**
+     * Install the gems in the configured installation directory with all
+     * the default settings
+     */
     public void install() {
         impl.install();
     }
+
+    /**
+     * Install the gems in the configuration installation directory with the given
+     * overwrite setting
+     *
+     * @param overwriteBehavior
+     */
+    public void install(DuplicateBehavior overwriteBehavior) {
+        impl.install(overwriteBehavior);
+    }
 }

src/test/groovy/com/github/jrubygradle/jem/GemInstallerSpec.groovy

@@ -4,7 +4,10 @@ import spock.lang.*
 import java.nio.file.Files
 import java.nio.file.Path
 
+import com.github.jrubygradle.jem.internal.GemInstaller as GemInstallerImpl
+
 /**
+ * Test the externally facing GemInstaller API
  */
 class GemInstallerSpec extends Specification {
     final String FIXTURES_ROOT = new File(['src', 'test', 'resources'].join(File.separator)).absolutePath
@@ -14,6 +17,13 @@ class GemInstallerSpec extends Specification {
     Path installDirPath = Files.createTempDirectory("geminstallerspec")
     String installDir = installDirPath as String
 
+    GemInstallerImpl mockedImpl() {
+        return Mock(GemInstallerImpl, constructorArgs: [
+                installDir,
+                [GEM_FIXTURE]
+                ])
+    }
+
     def "ctor should take a dir and single path"() {
         when:
         installer = new GemInstaller(installDir, GEM_FIXTURE)
@@ -45,4 +55,25 @@ class GemInstallerSpec extends Specification {
         then:
         installer instanceof GemInstaller
     }
+
+    def "install() should call our impl with defaults"() {
+        given:
+        GemInstallerImpl impl = mockedImpl()
+        GemInstaller installer = new GemInstaller(impl)
+        1 * impl.install()
+
+        expect:
+        installer.install()
+    }
+
+    def "install(DuplicateBehavior) should pass those attributes on to impl"() {
+        given:
+        GemInstaller.DuplicateBehavior behavior = GemInstaller.DuplicateBehavior.OVERWRITE
+        GemInstallerImpl impl = mockedImpl()
+        GemInstaller installer = new GemInstaller(impl)
+        1 * impl.install(behavior)
+
+        expect:
+        installer.install(behavior)
+    }
 }