Implement isPrimaryKey check, fix and refactor check tests (#250)

* Implement isPrimaryKey check.

* Fix and refactor checks tests.

* Check isPrimaryKey: use optional hint argument.

* Check tests: use List[str] instead of list[str].

* Check tests: fix isUnique check tests.

* Check tests: fix test_fail_hasMax test to use self.hasMax.

* Check tests: add case with hint into test_fail_isUnique.

* Check tests: update run_check return type to List[Row].

* Check isPrimaryKey: add comment abound columns Scala type conversion.

Author: nikie

docs/checks.md

@@ -15,7 +15,7 @@ Here are the current supported functionalities of Checks.
 |  | areAnyComplete(columns) | Done |
 |  | haveAnyCompleteness(columns, assertion) | Done |
 |  | isUnique(column) | Done |
-|  | isPrimaryKey(column, *columns) | Not Implemented |
+|  | isPrimaryKey(column, *columns) | Done |
 |  | hasUniqueness(columns, assertion) | Done |
 |  | hasDistinctness(columns, assertion) | Done |
 |  | hasUniqueValueRatio(columns, assertion) | Done |

pydeequ/checks.py

@@ -243,15 +243,18 @@ def isPrimaryKey(self, column, *columns, hint=None):
         Currently only checks uniqueness, but reserved for primary key checks if there is another
         assertion to run on primary key columns.
 
-        #  how does column and columns differ
-        :param str column: Column in Data Frame to run the assertion on.
+        Uniqueness is checked for the list of all columns: [column] + columns.
+
+        :param str column: The 1st column in Data Frame to run the assertion on.
+        :param list[str] columns: Additional columns to run the assertion on.
         :param str hint: A hint that states why a constraint could have failed.
-        :param list[str] columns: Columns to run the assertion on.
         :return: isPrimaryKey self: A Check.scala object that asserts completion in the columns.
         """
+        # This relies on Py4J's implicit conversion from Seq to varargs:
+        columns_seq = to_scala_seq(self._jvm, columns)
         hint = self._jvm.scala.Option.apply(hint)
-        print(f"Unsolved integration: {hint}")
-        raise NotImplementedError("Unsolved integration of Python tuple => varArgs")
+        self._Check = self._Check.isPrimaryKey(column, hint, columns_seq)
+        return self
 
     def hasUniqueness(self, columns, assertion, hint=None):
         """