Add support from #279 for custom base sha

Author: joshafeinberg

affectedmoduledetector/src/main/kotlin/com/dropbox/affectedmoduledetector/AffectedModuleDetector.kt

@@ -202,7 +202,13 @@ abstract class AffectedModuleDetector(protected val logger: Logger?) {
             val gitClient = GitClientImpl(
                 rootProject.projectDir,
                 logger,
-                commitShaProviderConfiguration = CommitShaProviderConfiguration(config.compareFrom, config.specifiedBranch, config.top, config.includeUncommitted),
+                commitShaProviderConfiguration = CommitShaProviderConfiguration(
+                    type = config.compareFrom,
+                    specifiedBranch = config.specifiedBranch,
+                    specifiedSha = config.specifiedRawCommitSha,
+                    top = config.top,
+                    includeUncommitted = config.includeUncommitted
+                ),
                 ignoredFiles = config.ignoredFiles
             )
 

affectedmoduledetector/src/main/kotlin/com/dropbox/affectedmoduledetector/GitClient.kt

@@ -26,6 +26,7 @@ import com.dropbox.affectedmoduledetector.commitshaproviders.ForkCommit
 import com.dropbox.affectedmoduledetector.commitshaproviders.PreviousCommit
 import com.dropbox.affectedmoduledetector.commitshaproviders.SpecifiedBranchCommit
 import com.dropbox.affectedmoduledetector.commitshaproviders.SpecifiedBranchCommitMergeBase
+import com.dropbox.affectedmoduledetector.commitshaproviders.SpecifiedRawCommitSha
 import com.dropbox.affectedmoduledetector.util.toOsSpecificLineEnding
 import com.dropbox.affectedmoduledetector.util.toOsSpecificPath
 import org.gradle.api.Project
@@ -228,6 +229,7 @@ internal abstract class GitChangedFilesSource :
 
     private fun getSha(): Sha {
         val specifiedBranch = parameters.commitShaProvider.specifiedBranch
+        val specifiedSha = parameters.commitShaProvider.specifiedSha
         val type = when (parameters.commitShaProvider.type) {
             "PreviousCommit" -> PreviousCommit()
             "ForkCommit" -> ForkCommit()
@@ -243,6 +245,12 @@ internal abstract class GitChangedFilesSource :
                 }
                 SpecifiedBranchCommitMergeBase(specifiedBranch)
             }
+            "SpecifiedRawCommitSha" -> {
+                requireNotNull(specifiedSha) {
+                    "Provide a Commit SHA for the specifiedRawCommitSha property when using SpecifiedRawCommitSha comparison strategy."
+                }
+                SpecifiedRawCommitSha(specifiedSha)
+            }
             else -> throw IllegalArgumentException("Unsupported compareFrom type")
         }
         return type.get(commandRunner)

affectedmoduledetector/src/main/kotlin/com/dropbox/affectedmoduledetector/commitshaproviders/CommitShaProvider.kt

@@ -11,6 +11,7 @@ interface CommitShaProvider : Serializable {
 data class CommitShaProviderConfiguration(
     val type: String,
     val specifiedBranch: String? = null,
+    val specifiedSha: String? = null,
     val top: Sha,
     val includeUncommitted: Boolean
 ) : Serializable