tests: use insta to test editor contents

It's tedious to update editor expectation manually. Let's dump the actual
content and test it after each command invocation.

tests/test_commit_command.rs

@@ -43,22 +43,19 @@ fn test_commit_with_editor() {
     // set a new one
     test_env.jj_cmd_success(&workspace_path, &["describe", "-m=initial"]);
     let edit_script = test_env.set_up_fake_editor();
-    std::fs::write(
-        edit_script,
-        "expect
-initial
-
-JJ: Lines starting with \"JJ: \" (like this one) will be removed.
-\0write
-modified",
-    )
-    .unwrap();
+    std::fs::write(edit_script, ["dump editor0", "write\nmodified"].join("\0")).unwrap();
     test_env.jj_cmd_success(&workspace_path, &["commit"]);
     insta::assert_snapshot!(get_log_output(&test_env, &workspace_path), @r###"
     @ 3df78bc2b9b5 (no description set)
     o 30a8c2b3d6eb modified
     o 000000000000 (no description set)
     "###);
+    insta::assert_snapshot!(
+        std::fs::read_to_string(test_env.env_root().join("editor0")).unwrap(), @r###"
+    initial
+
+    JJ: Lines starting with "JJ: " (like this one) will be removed.
+    "###);
 }
 
 #[test]

tests/test_describe_command.rs

@@ -38,19 +38,17 @@ fn test_describe() {
 
     // Check that the text file gets initialized with the current description and
     // make no changes
-    std::fs::write(
-        &edit_script,
-        r#"expect
-description from CLI
-
-JJ: Lines starting with "JJ: " (like this one) will be removed.
-"#,
-    )
-    .unwrap();
+    std::fs::write(&edit_script, "dump editor0").unwrap();
     let stdout = test_env.jj_cmd_success(&repo_path, &["describe"]);
     insta::assert_snapshot!(stdout, @r###"
     Nothing changed.
     "###);
+    insta::assert_snapshot!(
+        std::fs::read_to_string(test_env.env_root().join("editor0")).unwrap(), @r###"
+    description from CLI
+
+    JJ: Lines starting with "JJ: " (like this one) will be removed.
+    "###);
 
     // Set a description in editor
     std::fs::write(&edit_script, "write\ndescription from editor").unwrap();

tests/test_move_command.rs

@@ -365,26 +365,24 @@ fn test_move_description() {
     // If both descriptions were non-empty, we get asked for a combined description
     test_env.jj_cmd_success(&repo_path, &["undo"]);
     test_env.jj_cmd_success(&repo_path, &["describe", "-m", "source"]);
-    std::fs::write(
-        &edit_script,
-        r#"expect
-JJ: Enter a description for the combined commit.
-JJ: Description from the destination commit:
-destination
-
-JJ: Description from the source commit:
-source
-
-JJ: Lines starting with "JJ: " (like this one) will be removed.
-"#,
-    )
-    .unwrap();
+    std::fs::write(&edit_script, "dump editor0").unwrap();
     test_env.jj_cmd_success(&repo_path, &["move", "--to", "@-"]);
     insta::assert_snapshot!(get_description(&test_env, &repo_path, "@-"), @r###"
     destination
 
     source
     "###);
+    insta::assert_snapshot!(
+        std::fs::read_to_string(test_env.env_root().join("editor0")).unwrap(), @r###"
+    JJ: Enter a description for the combined commit.
+    JJ: Description from the destination commit:
+    destination
+
+    JJ: Description from the source commit:
+    source
+
+    JJ: Lines starting with "JJ: " (like this one) will be removed.
+    "###);
 
     // If the source's *content* doesn't become empty, then the source remains and
     // both descriptions are unchanged

tests/test_resolve_command.rs

@@ -80,8 +80,15 @@ fn test_resolution() {
 
     let editor_script = test_env.set_up_fake_editor();
     // Check that output file starts out empty and resolve the conflict
-    std::fs::write(&editor_script, "expect\n\0write\nresolution\n").unwrap();
+    std::fs::write(
+        &editor_script,
+        ["dump editor0", "write\nresolution\n"].join("\0"),
+    )
+    .unwrap();
     test_env.jj_cmd_success(&repo_path, &["resolve"]);
+    insta::assert_snapshot!(
+        std::fs::read_to_string(test_env.env_root().join("editor0")).unwrap(), @r###"
+    "###);
     insta::assert_snapshot!(test_env.jj_cmd_success(&repo_path, &["diff"]), 
     @r###"
     Resolved conflict in file:
@@ -105,17 +112,7 @@ fn test_resolution() {
     @"");
     std::fs::write(
         &editor_script,
-        "expect
-<<<<<<<
-%%%%%%%
--base
-+a
-+++++++
-b
->>>>>>>
-\0write
-resolution
-",
+        ["dump editor1", "write\nresolution\n"].join("\0"),
     )
     .unwrap();
     test_env.jj_cmd_success(
@@ -126,6 +123,16 @@ resolution
             "merge-tools.fake-editor.merge-tool-edits-conflict-markers=true",
         ],
     );
+    insta::assert_snapshot!(
+        std::fs::read_to_string(test_env.env_root().join("editor1")).unwrap(), @r###"
+    <<<<<<<
+    %%%%%%%
+    -base
+    +a
+    +++++++
+    b
+    >>>>>>>
+    "###);
     insta::assert_snapshot!(test_env.jj_cmd_success(&repo_path, &["diff"]), 
     @r###"
     Resolved conflict in file:
@@ -145,15 +152,9 @@ resolution
     @"");
     std::fs::write(
         &editor_script,
-        "expect
-<<<<<<<
-%%%%%%%
--base
-+a
-+++++++
-b
->>>>>>>
-\0write
+        [
+            "dump editor2",
+            "write
 <<<<<<<
 %%%%%%%
 -some
@@ -162,6 +163,8 @@ b
 conflict
 >>>>>>>
 ",
+        ]
+        .join("\0"),
     )
     .unwrap();
     test_env.jj_cmd_success(
@@ -172,6 +175,16 @@ conflict
             "merge-tools.fake-editor.merge-tool-edits-conflict-markers=true",
         ],
     );
+    insta::assert_snapshot!(
+        std::fs::read_to_string(test_env.env_root().join("editor2")).unwrap(), @r###"
+    <<<<<<<
+    %%%%%%%
+    -base
+    +a
+    +++++++
+    b
+    >>>>>>>
+    "###);
     // Note the "Modified" below
     insta::assert_snapshot!(test_env.jj_cmd_success(&repo_path, &["diff"]), 
     @r###"
@@ -197,8 +210,9 @@ conflict
     @"");
     std::fs::write(
         &editor_script,
-        "expect
-\0write
+        [
+            "dump editor3",
+            "write
 <<<<<<<
 %%%%%%%
 -some
@@ -207,9 +221,14 @@ conflict
 conflict
 >>>>>>>
 ",
+        ]
+        .join("\0"),
     )
     .unwrap();
     test_env.jj_cmd_success(&repo_path, &["resolve"]);
+    insta::assert_snapshot!(
+        std::fs::read_to_string(test_env.env_root().join("editor3")).unwrap(), @r###"
+    "###);
     // Note the "Resolved" below
     insta::assert_snapshot!(test_env.jj_cmd_success(&repo_path, &["diff"]), 
     @r###"

tests/test_split_command.rs

@@ -35,23 +35,7 @@ fn test_split_by_paths() {
     let edit_script = test_env.set_up_fake_editor();
     std::fs::write(
         edit_script,
-        "expect
-JJ: Enter commit description for the first part (parent).
-
-JJ: This part contains the following changes:
-JJ:     A file2
-
-JJ: Lines starting with \"JJ: \" (like this one) will be removed.
-\0next invocation
-\0expect
-JJ: Enter commit description for the second part (child).
-
-JJ: This part contains the following changes:
-JJ:     A file1
-JJ:     A file3
-
-JJ: Lines starting with \"JJ: \" (like this one) will be removed.
-",
+        ["dump editor0", "next invocation\n", "dump editor1"].join("\0"),
     )
     .unwrap();
     let stdout = test_env.jj_cmd_success(&repo_path, &["split", "file2"]);
@@ -60,6 +44,25 @@ JJ: Lines starting with \"JJ: \" (like this one) will be removed.
     Second part: 45833353d94e (no description set)
     Working copy now at: 45833353d94e (no description set)
     "###);
+    insta::assert_snapshot!(
+        std::fs::read_to_string(test_env.env_root().join("editor0")).unwrap(), @r###"
+    JJ: Enter commit description for the first part (parent).
+
+    JJ: This part contains the following changes:
+    JJ:     A file2
+
+    JJ: Lines starting with "JJ: " (like this one) will be removed.
+    "###);
+    insta::assert_snapshot!(
+        std::fs::read_to_string(test_env.env_root().join("editor1")).unwrap(), @r###"
+    JJ: Enter commit description for the second part (child).
+
+    JJ: This part contains the following changes:
+    JJ:     A file1
+    JJ:     A file3
+
+    JJ: Lines starting with "JJ: " (like this one) will be removed.
+    "###);
 
     let stdout = test_env.jj_cmd_success(&repo_path, &["log", "-T", "commit_id.short()"]);
     insta::assert_snapshot!(stdout, @r###"

tests/test_squash_command.rs

@@ -281,26 +281,24 @@ fn test_squash_description() {
     // If both descriptions were non-empty, we get asked for a combined description
     test_env.jj_cmd_success(&repo_path, &["undo"]);
     test_env.jj_cmd_success(&repo_path, &["describe", "-m", "source"]);
-    std::fs::write(
-        &edit_script,
-        r#"expect
-JJ: Enter a description for the combined commit.
-JJ: Description from the destination commit:
-destination
-
-JJ: Description from the source commit:
-source
-
-JJ: Lines starting with "JJ: " (like this one) will be removed.
-"#,
-    )
-    .unwrap();
+    std::fs::write(&edit_script, "dump editor0").unwrap();
     test_env.jj_cmd_success(&repo_path, &["squash"]);
     insta::assert_snapshot!(get_description(&test_env, &repo_path, "@-"), @r###"
     destination
 
     source
     "###);
+    insta::assert_snapshot!(
+        std::fs::read_to_string(test_env.env_root().join("editor0")).unwrap(), @r###"
+    JJ: Enter a description for the combined commit.
+    JJ: Description from the destination commit:
+    destination
+
+    JJ: Description from the source commit:
+    source
+
+    JJ: Lines starting with "JJ: " (like this one) will be removed.
+    "###);
 
     // If the source's *content* doesn't become empty, then the source remains and
     // both descriptions are unchanged

tests/test_unsquash_command.rs

@@ -247,26 +247,24 @@ fn test_unsquash_description() {
     // If both descriptions were non-empty, we get asked for a combined description
     test_env.jj_cmd_success(&repo_path, &["undo"]);
     test_env.jj_cmd_success(&repo_path, &["describe", "@-", "-m", "source"]);
-    std::fs::write(
-        &edit_script,
-        r#"expect
-JJ: Enter a description for the combined commit.
-JJ: Description from the destination commit:
-destination
-
-JJ: Description from the source commit:
-source
-
-JJ: Lines starting with "JJ: " (like this one) will be removed.
-"#,
-    )
-    .unwrap();
+    std::fs::write(&edit_script, "dump editor0").unwrap();
     test_env.jj_cmd_success(&repo_path, &["unsquash"]);
     insta::assert_snapshot!(get_description(&test_env, &repo_path, "@"), @r###"
     destination
 
     source
     "###);
+    insta::assert_snapshot!(
+        std::fs::read_to_string(test_env.env_root().join("editor0")).unwrap(), @r###"
+    JJ: Enter a description for the combined commit.
+    JJ: Description from the destination commit:
+    destination
+
+    JJ: Description from the source commit:
+    source
+
+    JJ: Lines starting with "JJ: " (like this one) will be removed.
+    "###);
 
     // If the source's *content* doesn't become empty, then the source remains and
     // both descriptions are unchanged