Add support for allow_duplicates!

cargo-insta/src/cli.rs

@@ -8,7 +8,7 @@ use std::{io, process};
 use console::{set_colors_enabled, style, Key, Term};
 use insta::Snapshot;
 use insta::_cargo_insta_support::{
-    is_ci, print_snapshot, print_snapshot_diff, SnapshotUpdate, TestRunner, ToolConfig,
+    is_ci, print_snapshot, SnapshotPrinter, SnapshotUpdate, TestRunner, ToolConfig,
     UnreferencedSnapshots,
 };
 use serde::Serialize;
@@ -246,7 +246,10 @@ fn query_snapshot(
             pkg_version,
         );
 
-        print_snapshot_diff(workspace_root, new, old, snapshot_file, line, *show_info);
+        let mut printer = SnapshotPrinter::new(workspace_root, old, new);
+        printer.set_snapshot_file(snapshot_file);
+        printer.set_line(line);
+        printer.set_show_info(*show_info);
 
         println!();
         println!(

src/lib.rs

@@ -295,7 +295,7 @@ pub mod _cargo_insta_support {
             Error as ToolConfigError, OutputBehavior, SnapshotUpdate, TestRunner, ToolConfig,
             UnreferencedSnapshots,
         },
-        output::{print_snapshot, print_snapshot_diff},
+        output::{print_snapshot, SnapshotPrinter},
         snapshot::PendingInlineSnapshot,
         snapshot::SnapshotContents,
         utils::is_ci,
@@ -311,7 +311,7 @@ pub use crate::redaction::{dynamic_redaction, sorted_redaction};
 pub mod _macro_support {
     pub use crate::content::Content;
     pub use crate::env::get_cargo_workspace;
-    pub use crate::runtime::{assert_snapshot, AutoName, ReferenceValue};
+    pub use crate::runtime::{assert_snapshot, with_allow_duplicates, AutoName, ReferenceValue};
 
     #[cfg(feature = "serde")]
     pub use crate::serialization::{serialize_value, SerializationFormat, SnapshotLocation};

src/macros.rs

@@ -554,3 +554,26 @@ macro_rules! glob {
         $crate::_macro_support::glob_exec(env!("CARGO_MANIFEST_DIR"), &base, $glob, $closure);
     }};
 }
+
+/// Utility macro to create a multi-snapshot run where all snapshots match.
+///
+/// Within this block, insta will allow an assertion to be run twice (even inline) without
+/// generating another snapshot.  Instead it will assert that snapshot expressions visited
+/// more than once are matching.
+///
+/// ```rust
+/// insta::allow_duplicates! {
+///     for x in (0..10).step_by(2) {
+///         let is_even = x % 2 == 0;
+///         insta::assert_debug_snapshot!(is_even, @"true");
+///     }
+/// }
+/// ```
+#[macro_export]
+macro_rules! allow_duplicates {
+    ($($x:tt)*) => {
+        $crate::_macro_support::with_allow_duplicates(|| {
+            $($x)*
+        })
+    }
+}