🛑 Error in showing error

Project.toml

@@ -2,7 +2,7 @@ name = "Pluto"
 uuid = "c3e4b0f8-55cb-11ea-2926-15256bba5781"
 license = "MIT"
 authors = ["Fons van der Plas <[email protected]>", "Mikołaj Bochenski <[email protected]>"]
-version = "0.5.12"
+version = "0.5.13"
 
 [deps]
 Distributed = "8ba89e20-285c-5b6f-9357-94700520ee1b"

src/notebookserver/FormatOutput.jl

@@ -42,7 +42,7 @@ function format_output(val::Any)::Tuple{String, MIME}
         try
             Base.invokelatest(repr, mime, val; context = iocontext), mime
         catch ex
-            Base.invokelatest(repr, mime, ex; context = iocontext), mime
+            "Failed to show value: \n" * sprint(showerror, ex, stacktrace(backtrace())), MIME("text/plain")
         end
     end
 end

src/notebookserver/Notebook.jl

@@ -98,7 +98,7 @@ end
 
 save_notebook(notebook::Notebook) = save_notebook(notebook, notebook.path)
 
-function load_notebook(io, path)
+function load_notebook_nobackup(io, path)
     firstline = String(readline(io))
 
     if firstline != "### A Pluto.jl notebook ###"
@@ -149,21 +149,26 @@ function load_notebook(io, path)
     Notebook(path, ordered_cells)
 end
 
+function load_notebook_nobackup(path::String)
+    local loaded
+    open(path, "r") do io
+        loaded = load_notebook_nobackup(io, path)
+    end
+    loaded
+end
+
 function load_notebook(path::String)
     backupPath = path
     while isfile(backupPath)
         backupPath = backupPath * ".backup"
     end
     cp(path, backupPath)
 
-    local loaded
-    open(path, "r") do io
-        loaded = load_notebook(io, path)
-    end
+    loaded = load_notebook_nobackup(path)
 
     save_notebook(loaded)
 
-    if only_versions_differ(path, backupPath)
+    if only_versions_or_lineorder_differ(path, backupPath)
         rm(backupPath)
     else
         @warn "Old Pluto notebook might not have loaded correctly. Backup saved to: " backupPath
@@ -182,6 +187,13 @@ function move_notebook(notebook::Notebook, newpath::String)
     rm(oldpath)
 end
 
+"Check if two savefiles are identical, up to their version numbers and a possible line shuffle.
+
+If a notebook has not yet had all of its cells run, we can't deduce the topological cell order."
+function only_versions_or_lineorder_differ(pathA::AbstractString, pathB::AbstractString)
+    Set(readlines(pathA)[3:end]) == Set(readlines(pathB)[3:end])
+end
+
 function only_versions_differ(pathA::AbstractString, pathB::AbstractString)
     readlines(pathA)[3:end] == readlines(pathB)[3:end]
 end

src/webserver/Dynamic.jl

@@ -138,6 +138,7 @@ responses[:deletecell] = (body, notebook::Notebook, cell::Cell; initiator::Union
 
         filter!(c->c.uuid ≠ to_delete.uuid, notebook.cells)
         putnotebookupdates!(notebook, clientupdate_cell_deleted(notebook, to_delete, initiator=initiator))
+        save_notebook(notebook) # this might be "too late", but it will save the latest version of `notebook` anyways
     end
 end
 

test/Notebook.jl

@@ -1,6 +1,6 @@
 using Test
 using Pluto
-import Pluto: samplenotebook, Notebook ,Cell, load_notebook, save_notebook
+import Pluto: samplenotebook, Notebook ,Cell, load_notebook, load_notebook_nobackup, save_notebook, run_reactive!
 
 function notebook_inputs_equal(nbA, nbB)
     x = normpath(nbA.path) == normpath(nbB.path)
@@ -23,28 +23,34 @@ end
     notebookA = samplenotebook()
     notebookB = Notebook(joinpath(tempdir(), "é🧡💛.jl"), [
         Cell("z = y"),
-        Cell("y = 1")
+        Cell("v = u"),
+        Cell("y = x"),
+        Cell("x = w"),
+        Cell("using Base"),
+        Cell("t = 1"),
+        Cell("w = v"),
+        Cell("u = t"),
     ])
 
     @testset "I/O" begin
         @test let
             nb = notebookB
             save_notebook(nb)
-            result = load_notebook(nb.path)
+            result = load_notebook_nobackup(nb.path)
             notebook_inputs_equal(nb, result)
         end
     end
     @testset "Line endings" for nb in [notebookA, notebookB]
         file_contents = sprint(save_notebook, nb)
 
         @test let
-            result = sread(load_notebook, file_contents, nb.path)
+            result = sread(load_notebook_nobackup, file_contents, nb.path)
             notebook_inputs_equal(nb, result)
         end
 
         @test let
             file_contents_windowsed = replace(file_contents, "\n" => "\r\n")
-            result_windowsed = sread(load_notebook, file_contents_windowsed, nb.path)
+            result_windowsed = sread(load_notebook_nobackup, file_contents_windowsed, nb.path)
             notebook_inputs_equal(nb, result_windowsed)
         end
     end
@@ -55,10 +61,20 @@ end
         ])
         @test let
             file_contents = sprint(save_notebook, nb)
-            result = sread(load_notebook, sprint(save_notebook, nb), nb.path)
+            result = sread(load_notebook_nobackup, sprint(save_notebook, nb), nb.path)
             notebook_inputs_equal(nb, result)
         end
     end
+    @testset "Backup" begin
+        notebookA.path = tempname() * ".jl"
+        notebookB.path = tempname() * ".jl"
+        backup_path = notebookB.path * ".backup"
+        isfile(backup_path) && rm(backup_path)
+        run_reactive!(notebookB, notebookB.cells)
+        save_notebook(notebookB)
+        notebookC = load_notebook(notebookB.path)
+        @test !isfile(backup_path)
+    end
 
     # TODO: tests for things mentioned in https://github.com/fonsp/Pluto.jl/issues/9
     # TODO: test bad dirs, filenames, permissions