Add more tests for the PIPE operator.

--
MOS_MIGRATED_REVID=101364893
diff --git a/src/test/java/com/google/devtools/build/lib/syntax/EvaluationTest.java b/src/test/java/com/google/devtools/build/lib/syntax/EvaluationTest.java
index 14988cb..6b107a1 100644
--- a/src/test/java/com/google/devtools/build/lib/syntax/EvaluationTest.java
+++ b/src/test/java/com/google/devtools/build/lib/syntax/EvaluationTest.java
@@ -298,6 +298,7 @@
         .testStatement("-7 / 2", -4)
         .testStatement("-7 / -2", 3)
         .testStatement("2147483647 / 2", 1073741823)
+        .testIfErrorContains("unsupported operand type(s) for /: 'string' and 'int'", "'str' / 2")
         .testIfExactError("integer division by zero", "5 / 0");
   }