[Spark] Use correctly formatted commit in CommitCoordinatorClientImpl…

…SuiteBase (#4192)

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#### Which Delta project/connector is this regarding?
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- [x] Spark
- [ ] Standalone
- [ ] Flink
- [ ] Kernel
- [ ] Other (fill in here)

## Description

The helpers for commit coordinator tests currently write plain strings
for commits. This PR switches these helpers to use actual commit json
instead so that the log generated by these helpers are correctly
formatted.

## How was this patch tested?
Existing unit tests

## Does this PR introduce _any_ user-facing changes?
No

spark/src/test/scala/org/apache/spark/sql/delta/coordinatedcommits/CommitCoordinatorClientImplSuiteBase.scala

@@ -24,7 +24,7 @@ import scala.collection.JavaConverters._
 import scala.concurrent.duration._
 
 import org.apache.spark.sql.delta.DeltaLog
-import org.apache.spark.sql.delta.actions.{CommitInfo, Metadata, Protocol}
+import org.apache.spark.sql.delta.actions.{Action, CommitInfo, Metadata, Protocol}
 import org.apache.spark.sql.delta.storage.{LogStore, LogStoreProvider}
 import org.apache.spark.sql.delta.test.{DeltaSQLCommandTest, DeltaSQLTestUtils}
 import org.apache.spark.sql.delta.test.DeltaTestImplicits._
@@ -122,7 +122,10 @@ trait CommitCoordinatorClientImplSuiteBase extends QueryTest
   }
 
   protected def writeCommitZero(logPath: Path): Unit = {
-    store.write(FileNames.unsafeDeltaFile(logPath, 0), Iterator("0", "0"), overwrite = false)
+    val commitInfo = CommitInfo.empty(version = Some(0)).withTimestamp(0)
+      .copy(inCommitTimestamp = Some(0))
+    val actions = Iterator(commitInfo.json, Metadata().json, Protocol().json)
+    store.write(FileNames.unsafeDeltaFile(logPath, 0), actions, overwrite = false)
   }
 
   /**
@@ -163,7 +166,7 @@ trait CommitCoordinatorClientImplSuiteBase extends QueryTest
     }
     tableCommitCoordinatorClient.commit(
       version,
-      Iterator(s"$version", s"$timestamp"),
+      Iterator(commitInfo.json),
       updatedActions).getCommit
   }
 
@@ -173,9 +176,13 @@ trait CommitCoordinatorClientImplSuiteBase extends QueryTest
       timestampOpt: Option[Long] = None): Unit = {
     val delta = FileNames.unsafeDeltaFile(logPath, version)
     if (timestampOpt.isDefined) {
-      assert(store.read(delta, sessionHadoopConf) == Seq(s"$version", s"${timestampOpt.get}"))
+      val commitInfo = CommitInfo.empty(version = Some(version))
+        .withTimestamp(timestampOpt.get)
+        .copy(inCommitTimestamp = timestampOpt)
+      assert(store.read(delta, sessionHadoopConf).head == commitInfo.json)
     } else {
-      assert(store.read(delta, sessionHadoopConf).take(1) == Seq(s"$version"))
+      assert(Action.fromJson(store.read(delta, sessionHadoopConf).head)
+        .isInstanceOf[CommitInfo])
     }
   }