Fewer test cases and fewer tests for left/right/substr

rename t1234 to t1234<index>

rename QTestCase to SubstringTestCase

remove redundant unit test

 unify test naming

with struct test

tests pass locally

format

test impl to make more in line with refactor. next add struct test, maybe.

left impl

right impl

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/stringExpressions.scala

@@ -1987,15 +1987,15 @@ case class Right(str: Expression, len: Expression) extends RuntimeReplaceable
 
   override lazy val replacement: Expression = If(
     IsNull(str),
-    Literal(null, StringType),
+    Literal(null, str.dataType),
     If(
       LessThanOrEqual(len, Literal(0)),
-      Literal(UTF8String.EMPTY_UTF8, StringType),
+      Literal(UTF8String.EMPTY_UTF8, str.dataType),
       new Substring(str, UnaryMinus(len))
     )
   )
 
-  override def inputTypes: Seq[AbstractDataType] = Seq(StringType, IntegerType)
+  override def inputTypes: Seq[AbstractDataType] = Seq(StringTypeAnyCollation, IntegerType)
   override def left: Expression = str
   override def right: Expression = len
   override protected def withNewChildrenInternal(
@@ -2026,7 +2026,7 @@ case class Left(str: Expression, len: Expression) extends RuntimeReplaceable
   override lazy val replacement: Expression = Substring(str, Literal(1), len)
 
   override def inputTypes: Seq[AbstractDataType] = {
-    Seq(TypeCollection(StringType, BinaryType), IntegerType)
+    Seq(TypeCollection(StringTypeAnyCollation, BinaryType), IntegerType)
   }
 
   override def left: Expression = str

sql/core/src/test/scala/org/apache/spark/sql/CollationStringExpressionsSuite.scala

@@ -212,6 +212,49 @@ class CollationStringExpressionsSuite
     })
   }
 
+  test("Support Left/Right/Substr with collation") {
+    case class SubstringTestCase(query: String, collation: String, result: Row)
+    val checks = Seq("utf8_binary_lcase", "utf8_binary", "unicode", "unicode_ci").flatMap(
+      c => Seq(
+        SubstringTestCase("select substr('example' collate " + c + ", 1, 100)", c, Row("example")),
+        SubstringTestCase("select substr('example' collate " + c + ", 2, 2)", c, Row("xa")),
+        SubstringTestCase("select substr('example' collate " + c + ", 0, 0)", c, Row("")),
+        SubstringTestCase("select substr('example' collate " + c + ", -3, 2)", c, Row("pl")),
+        SubstringTestCase("select substr(' a世a ' collate " + c + ", 2, 3)", c, Row("a世a")), // scalastyle:ignore
+        SubstringTestCase("select left(' a世a ' collate " + c + ", 3)", c, Row(" a世")), // scalastyle:ignore
+        SubstringTestCase("select right(' a世a ' collate " + c + ", 3)", c, Row("世a ")), // scalastyle:ignore
+        SubstringTestCase("select left('AaAaAaAa000000' collate " + c + ", 3)", c, Row("AaA")),
+        SubstringTestCase("select right('AaAaAaAa000000' collate " + c + ", 3)", c, Row("000")),
+        SubstringTestCase("select substr('' collate " + c + ", 1, 1)", c, Row("")),
+        SubstringTestCase("select left('' collate " + c + ", 1)", c, Row("")),
+        SubstringTestCase("select right('' collate " + c + ", 1)", c, Row("")),
+        // improper values
+        SubstringTestCase("select left(null collate " + c + ", 1)", c, Row(null)),
+        SubstringTestCase("select right(null collate " + c + ", 1)", c, Row(null)),
+        SubstringTestCase("select substr(null collate " + c + ", 1)", c, Row(null)),
+        SubstringTestCase("select substr(null collate " + c + ", 1, 1)", c, Row(null)),
+        SubstringTestCase("select left(null collate " + c + ", null)", c, Row(null)),
+        SubstringTestCase("select right(null collate " + c + ", null)", c, Row(null)),
+        SubstringTestCase("select substr(null collate " + c + ", null)", c, Row(null)),
+        SubstringTestCase("select substr(null collate " + c + ", null, null)", c, Row(null)),
+        SubstringTestCase("select left('AaAaAaAa000000' collate " + c + ", null)", c, Row(null)),
+        SubstringTestCase("select right('AaAaAaAa000000' collate " + c + ", null)", c, Row(null)),
+        SubstringTestCase("select substr('AaAaAaAa000000' collate " + c + ", null)", c, Row(null)),
+        SubstringTestCase("select substr('AaAaAaAa0' collate " + c + ", null, null)", c, Row(null)),
+        SubstringTestCase("select right('' collate " + c + ", null)", c, Row(null)),
+        SubstringTestCase("select substr('' collate " + c + ", null)", c, Row(null)),
+        SubstringTestCase("select substr('' collate " + c + ", null, null)", c, Row(null)),
+        SubstringTestCase("select left('' collate " + c + ", null)", c, Row(null))
+      )
+    )
+
+    checks.foreach { check =>
+      // Result & data type
+      checkAnswer(sql(check.query), check.result)
+      assert(sql(check.query).schema.fields.head.dataType.sameType(StringType(check.collation)))
+    }
+  }
+
   // TODO: Add more tests for other string expressions
 
 }