Added some tests.

tests/it/array/primitive/mod.rs

@@ -3,6 +3,7 @@ use std::iter::FromIterator;
 use arrow2::{
     array::*,
     bitmap::Bitmap,
+    buffer::Buffer,
     datatypes::*,
     types::{days_ms, months_days_ns},
 };
@@ -256,3 +257,10 @@ fn months_days_ns() {
     let a = array.values().as_slice();
     assert_eq!(a, data.as_ref());
 }
+
+#[test]
+#[should_panic]
+fn wrong_data_type() {
+    let values = Buffer::from(b"abbb");
+    PrimitiveArray::from_data(DataType::Utf8, values, None);
+}

tests/it/array/primitive/mutable.rs

@@ -148,3 +148,10 @@ fn try_from_trusted_len_iter() {
     let a = MutablePrimitiveArray::try_from_trusted_len_iter(iter).unwrap();
     assert_eq!(a, MutablePrimitiveArray::from([Some(1), Some(1)]));
 }
+
+#[test]
+#[should_panic]
+fn wrong_data_type() {
+    let values = MutableBuffer::from(b"abbb");
+    MutablePrimitiveArray::from_data(DataType::Utf8, values, None);
+}

tests/it/array/utf8/mod.rs

@@ -107,3 +107,27 @@ fn try_from_trusted_len_iter() {
         Utf8Array::<i32>::from_data(DataType::Utf8, offsets, values, None)
     );
 }
+
+#[test]
+#[should_panic]
+fn not_utf8() {
+    let offsets = Buffer::from(&[0, 4]);
+    let values = Buffer::from([0, 159, 146, 150]); // invalid utf8
+    Utf8Array::<i32>::from_data(DataType::Utf8, offsets, values, None);
+}
+
+#[test]
+#[should_panic]
+fn wrong_offsets() {
+    let offsets = Buffer::from(&[0, 5, 4]); // invalid offsets
+    let values = Buffer::from(b"abbbbb");
+    Utf8Array::<i32>::from_data(DataType::Utf8, offsets, values, None);
+}
+
+#[test]
+#[should_panic]
+fn wrong_data_type() {
+    let offsets = Buffer::from(&[0, 4]); // invalid offsets
+    let values = Buffer::from(b"abbb");
+    Utf8Array::<i32>::from_data(DataType::Int8, offsets, values, None);
+}

tests/it/array/utf8/mutable.rs

@@ -1,5 +1,7 @@
 use arrow2::array::{Array, MutableUtf8Array, Utf8Array};
 use arrow2::bitmap::Bitmap;
+use arrow2::buffer::MutableBuffer;
+use arrow2::datatypes::DataType;
 
 #[test]
 fn capacities() {
@@ -17,3 +19,29 @@ fn push_null() {
     let array: Utf8Array<i32> = array.into();
     assert_eq!(array.validity(), &Some(Bitmap::from([false])));
 }
+
+/// Safety guarantee
+#[test]
+#[should_panic]
+fn not_utf8() {
+    let offsets = MutableBuffer::from(&[0, 4]);
+    let values = MutableBuffer::from([0, 159, 146, 150]); // invalid utf8
+    MutableUtf8Array::<i32>::from_data(DataType::Utf8, offsets, values, None);
+}
+
+/// Safety guarantee
+#[test]
+#[should_panic]
+fn wrong_offsets() {
+    let offsets = MutableBuffer::from(&[0, 5, 4]); // invalid offsets
+    let values = MutableBuffer::from(b"abbbbb");
+    MutableUtf8Array::<i32>::from_data(DataType::Utf8, offsets, values, None);
+}
+
+#[test]
+#[should_panic]
+fn wrong_data_type() {
+    let offsets = MutableBuffer::from(&[0, 4]); // invalid offsets
+    let values = MutableBuffer::from(b"abbb");
+    MutableUtf8Array::<i32>::from_data(DataType::Int8, offsets, values, None);
+}