Enforce starting newlines

CHANGELOG.md

@@ -8,6 +8,14 @@ All notable changes to insta and cargo-insta are documented here.
   nextest. Shows a deprecation warning when nextest is used with doctests without this flag, to prepare `cargo insta` to no longer run
   a separate doctest process when using nextest in the future. #803
 
+- We no longer trim starting newlines during assertions, which allows asserting
+  the number of leading newlines match. Existing assertions with different
+  leading newlines will pass and print a warning suggesting running with
+  `--force-update-snapshots`.  They may fail in the future.  (Note that we still
+  currently allow differing _trailing_ newlines, though may adjust this in the
+  future).  #563
+
+
 ## 1.43.2
 
 - Fix panics when `cargo metadata` fails to execute or parse (e.g., when cargo is not in PATH or returns invalid output). Now falls back to using the manifest directory as the workspace root. #798 (@adriangb)

cargo-insta/tests/functional/binary.rs

@@ -26,8 +26,7 @@ fn test_binary_snapshot() {
     assert_snapshot!(test_project.file_tree_diff(), @r"
     --- Original file tree
     +++ Updated file tree
-    @@ -1,4 +1,8 @@
-
+    @@ -1,3 +1,7 @@
     +  Cargo.lock
        Cargo.toml
        src
@@ -66,8 +65,7 @@ fn test_binary_snapshot() {
     assert_snapshot!(test_project.file_tree_diff(), @r"
     --- Original file tree
     +++ Updated file tree
-    @@ -1,4 +1,8 @@
-
+    @@ -1,3 +1,7 @@
     +  Cargo.lock
        Cargo.toml
        src
@@ -123,8 +121,7 @@ fn test_binary_snapshot() {
     assert_snapshot!(test_project.file_tree_diff(), @r"
     --- Original file tree
     +++ Updated file tree
-    @@ -1,4 +1,10 @@
-
+    @@ -1,3 +1,9 @@
     +  Cargo.lock
        Cargo.toml
        src
@@ -147,8 +144,7 @@ fn test_binary_snapshot() {
     assert_snapshot!(test_project.file_tree_diff(), @r"
     --- Original file tree
     +++ Updated file tree
-    @@ -1,4 +1,8 @@
-
+    @@ -1,3 +1,7 @@
     +  Cargo.lock
        Cargo.toml
        src
@@ -199,8 +195,7 @@ fn test_binary_snapshot() {
     assert_snapshot!(test_project.file_tree_diff(), @r"
     --- Original file tree
     +++ Updated file tree
-    @@ -1,4 +1,6 @@
-
+    @@ -1,3 +1,5 @@
     +  Cargo.lock
        Cargo.toml
        src
@@ -237,8 +232,7 @@ fn test() {
     assert_snapshot!(test_project.file_tree_diff(), @r"
     --- Original file tree
     +++ Updated file tree
-    @@ -1,4 +1,7 @@
-
+    @@ -1,3 +1,6 @@
     +  Cargo.lock
        Cargo.toml
        src
@@ -268,8 +262,7 @@ fn test() {
     assert_snapshot!(test_project.file_tree_diff(), @r"
     --- Original file tree
     +++ Updated file tree
-    @@ -1,4 +1,8 @@
-
+    @@ -1,3 +1,7 @@
     +  Cargo.lock
        Cargo.toml
        src
@@ -308,8 +301,7 @@ fn test() {
     assert_snapshot!(test_project.file_tree_diff(), @r"
     --- Original file tree
     +++ Updated file tree
-    @@ -1,4 +1,8 @@
-
+    @@ -1,3 +1,7 @@
     +  Cargo.lock
        Cargo.toml
        src
@@ -340,8 +332,7 @@ fn test() {
     assert_snapshot!(test_project.file_tree_diff(), @r"
     --- Original file tree
     +++ Updated file tree
-    @@ -1,4 +1,7 @@
-
+    @@ -1,3 +1,6 @@
     +  Cargo.lock
        Cargo.toml
        src
@@ -381,8 +372,7 @@ fn test_snapshot() {
     assert_snapshot!(test_project.file_tree_diff(), @r"
     --- Original file tree
     +++ Updated file tree
-    @@ -1,4 +1,8 @@
-
+    @@ -1,3 +1,7 @@
     +  Cargo.lock
        Cargo.toml
        src
@@ -411,8 +401,7 @@ fn test_snapshot() {
     assert_snapshot!(test_project.file_tree_diff(), @r"
     --- Original file tree
     +++ Updated file tree
-    @@ -1,4 +1,6 @@
-
+    @@ -1,3 +1,5 @@
     +  Cargo.lock
        Cargo.toml
        src

cargo-insta/tests/functional/delete_pending.rs

@@ -45,8 +45,7 @@ fn test_snapshot_file() {
     assert_snapshot!(test_project.file_tree_diff(), @r"
     --- Original file tree
     +++ Updated file tree
-    @@ -1,4 +1,7 @@
-
+    @@ -1,3 +1,6 @@
     +  Cargo.lock
        Cargo.toml
        src
@@ -70,8 +69,7 @@ fn test_snapshot_file() {
     assert_snapshot!(test_project.file_tree_diff(), @r"
     --- Original file tree
     +++ Updated file tree
-    @@ -1,4 +1,6 @@
-
+    @@ -1,3 +1,5 @@
     +  Cargo.lock
        Cargo.toml
        src
@@ -116,8 +114,7 @@ fn test_file_snapshot() {
     assert_snapshot!(test_project.file_tree_diff(), @r"
     --- Original file tree
     +++ Updated file tree
-    @@ -1,4 +1,7 @@
-
+    @@ -1,3 +1,6 @@
     +  Cargo.lock
        Cargo.toml
        src
@@ -158,8 +155,7 @@ fn test_file_snapshot() {
     assert_snapshot!(test_project.file_tree_diff(), @r"
     --- Original file tree
     +++ Updated file tree
-    @@ -1,4 +1,9 @@
-
+    @@ -1,3 +1,8 @@
     +  Cargo.lock
        Cargo.toml
        src
@@ -183,8 +179,7 @@ fn test_file_snapshot() {
     assert_snapshot!(test_project.file_tree_diff(), @r"
     --- Original file tree
     +++ Updated file tree
-    @@ -1,4 +1,7 @@
-
+    @@ -1,3 +1,6 @@
     +  Cargo.lock
        Cargo.toml
        src
@@ -206,8 +201,7 @@ fn test_file_snapshot() {
     assert_snapshot!(test_project.file_tree_diff(), @r"
     --- Original file tree
     +++ Updated file tree
-    @@ -1,4 +1,9 @@
-
+    @@ -1,3 +1,8 @@
     +  Cargo.lock
        Cargo.toml
        src
@@ -250,8 +244,7 @@ fn test_file_snapshot() {
     assert_snapshot!(test_project.file_tree_diff(), @r"
     --- Original file tree
     +++ Updated file tree
-    @@ -1,4 +1,7 @@
-
+    @@ -1,3 +1,6 @@
     +  Cargo.lock
        Cargo.toml
        src