Move assert_df_eq to polars_core

crates/polars-core/src/testing.rs

@@ -164,6 +164,18 @@ impl PartialEq for DataFrame {
     }
 }
 
+/// Asserts that two expressions of type [`DataFrame`] are equal according to [`DataFrame::equals`]
+/// at runtime. If the expression are not equal, the program will panic with a message that displays
+/// both dataframes.
+#[macro_export]
+macro_rules! assert_df_eq {
+    ($a:expr, $b:expr $(,)?) => {
+        let a: &$crate::frame::DataFrame = &$a;
+        let b: &$crate::frame::DataFrame = &$b;
+        assert!(a.equals(b), "expected {:?}\nto equal {:?}", a, b);
+    };
+}
+
 #[cfg(test)]
 mod test {
     use crate::prelude::*;
@@ -194,6 +206,19 @@ mod test {
         assert!(df1.equals(&df1))
     }
 
+    #[test]
+    fn assert_df_eq_passes() {
+        let df = df!("a" => [1], "b" => [2]).unwrap();
+        assert_df_eq!(df, df);
+        drop(df); // Ensure `assert_df_eq!` does not consume its arguments.
+    }
+
+    #[test]
+    #[should_panic(expected = "to equal")]
+    fn assert_df_eq_panics() {
+        assert_df_eq!(df!("a" => [1]).unwrap(), df!("a" => [2]).unwrap(),);
+    }
+
     #[test]
     fn test_df_partialeq() {
         let df1 = df!("a" => &[1, 2, 3],

crates/polars/tests/it/io/ipc_stream.rs

@@ -2,8 +2,8 @@
 mod test {
     use std::io::Cursor;
 
-    use polars_core::df;
     use polars_core::prelude::*;
+    use polars_core::{assert_df_eq, df};
     use polars_io::ipc::*;
     use polars_io::{SerReader, SerWriter};
 
@@ -21,14 +21,6 @@ mod test {
         buf
     }
 
-    macro_rules! assert_df_eq {
-        ($a:expr, $b:expr) => {
-            let a: &polars_core::frame::DataFrame = &$a;
-            let b: &polars_core::frame::DataFrame = &$b;
-            assert!(a.equals(b), "expected {:?}\nto equal {:?}", a, b);
-        };
-    }
-
     #[test]
     fn write_and_read_ipc_stream() {
         let df = create_df();