[ML] testEstimatorAndModelReadWrite should call checkModelData

## What changes were proposed in this pull request?
Although we defined ```checkModelData``` in [```read/write``` test](https://github.com/apache/spark/blob/master/mllib/src/test/scala/org/apache/spark/ml/regression/LinearRegressionSuite.scala#L994) of ML estimators/models and pass it to ```testEstimatorAndModelReadWrite```, ```testEstimatorAndModelReadWrite``` omits to call ```checkModelData``` to check the equality of model data. So actually we did not run the check of model data equality for all test cases currently, we should fix it.
BTW, fix the bug of LDA read/write test which did not set ```docConcentration```. This bug should have failed test, but it does not complain because we did not run ```checkModelData``` actually.
cc jkbradley mengxr
## How was this patch tested?
No new unit test, should pass the exist ones.

Author: Yanbo Liang <ybliang8@gmail.com>

Closes #11513 from yanboliang/ml-check-model-data.

2 files changed, 5 insertions, 1 deletions

diff --git a/mllib/src/test/scala/org/apache/spark/ml/clustering/LDASuite.scala b/mllib/src/test/scala/org/apache/spark/ml/clustering/LDASuite.scala
index 03270401ad..a3a8f65eac 100644
--- a/mllib/src/test/scala/org/apache/spark/ml/clustering/LDASuite.scala
+++ b/mllib/src/test/scala/org/apache/spark/ml/clustering/LDASuite.scala
@@ -52,7 +52,8 @@ object LDASuite {
     "checkpointInterval" -> 30,
     "learningOffset" -> 1023.0,
     "learningDecay" -> 0.52,
-    "subsamplingRate" -> 0.051
+    "subsamplingRate" -> 0.051,
+    "docConcentration" -> Array(2.0)
   )
 }
 
diff --git a/mllib/src/test/scala/org/apache/spark/ml/util/DefaultReadWriteTest.scala b/mllib/src/test/scala/org/apache/spark/ml/util/DefaultReadWriteTest.scala
index 0aa774b660..8e5365af84 100644
--- a/mllib/src/test/scala/org/apache/spark/ml/util/DefaultReadWriteTest.scala
+++ b/mllib/src/test/scala/org/apache/spark/ml/util/DefaultReadWriteTest.scala
@@ -82,6 +82,7 @@ trait DefaultReadWriteTest extends TempDirectory { self: Suite =>
    *  - Explicitly set Params, and train model
    *  - Test save/load using [[testDefaultReadWrite()]] on Estimator and Model
    *  - Check Params on Estimator and Model
+   *  - Compare model data
    *
    * This requires that the [[Estimator]] and [[Model]] share the same set of [[Param]]s.
    * @param estimator  Estimator to test
@@ -117,6 +118,8 @@ trait DefaultReadWriteTest extends TempDirectory { self: Suite =>
       val param = model.getParam(p)
       assert(model.get(param).get === model2.get(param).get)
     }
+
+    checkModelData(model, model2)
   }
 }