From 44f1b6e0116b5fca2a89e2d62e1bf86f22bf3fc7 Mon Sep 17 00:00:00 2001
From: Cocoa <89497197+cocoa-xu@users.noreply.github.com>
Date: Thu, 4 Nov 2021 01:12:41 +0000
Subject: [PATCH 01/12] save static vegalite plot to livemd

---
 lib/livebook/live_markdown/export.ex |  4 ++++
 lib/livebook/live_markdown/import.ex | 15 ++++++++++++++-
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/lib/livebook/live_markdown/export.ex b/lib/livebook/live_markdown/export.ex
index d236b64974e..a8a0d2c6917 100644
--- a/lib/livebook/live_markdown/export.ex
+++ b/lib/livebook/live_markdown/export.ex
@@ -153,6 +153,10 @@ defmodule Livebook.LiveMarkdown.Export do
     [delimiter, "output\n", text, "\n", delimiter]
   end
 
+  defp render_output({:vega_lite_static, vegalite_data}) do
+    ["```", "vega_lite_static\n", Jason.encode!(vegalite_data), "\n", "```"]
+  end
+
   defp render_output(_output), do: :ignored
 
   defp get_elixir_cell_code(%{source: source, disable_formatting: true}),
diff --git a/lib/livebook/live_markdown/import.ex b/lib/livebook/live_markdown/import.ex
index 81ee7312ddd..19c3a8a68eb 100644
--- a/lib/livebook/live_markdown/import.ex
+++ b/lib/livebook/live_markdown/import.ex
@@ -187,6 +187,16 @@ defmodule Livebook.LiveMarkdown.Import do
     take_outputs(ast, [output | outputs])
   end
 
+  defp take_outputs(
+         [{"pre", _, [{"code", [{"class", "vega_lite_static"}], [output], %{}}], %{}} | ast],
+         outputs
+       ) do
+    case Jason.decode(output) do
+      {:ok, data} -> take_outputs(ast, [{:vega_lite_static, data} | outputs])
+      _ -> take_outputs(ast, outputs)
+    end
+  end
+
   defp take_outputs(ast, outputs), do: {outputs, ast}
 
   # Builds a notebook from the list of elements obtained in the previous step.
@@ -198,7 +208,7 @@ defmodule Livebook.LiveMarkdown.Import do
   defp build_notebook([{:cell, :elixir, source, outputs} | elems], cells, sections, messages) do
     {metadata, elems} = grab_metadata(elems)
     attrs = cell_metadata_to_attrs(:elixir, metadata)
-    outputs = Enum.map(outputs, &{:text, &1})
+    outputs = Enum.map(outputs, fn output -> if is_tuple(output), do: output, else: {:text, output} end )
     cell = %{Notebook.Cell.new(:elixir) | source: source, outputs: outputs} |> Map.merge(attrs)
     build_notebook(elems, [cell | cells], sections, messages)
   end
@@ -346,6 +356,9 @@ defmodule Livebook.LiveMarkdown.Import do
       {"reevaluate_automatically", reevaluate_automatically}, attrs ->
         Map.put(attrs, :reevaluate_automatically, reevaluate_automatically)
 
+      {"output_is_vega", output_is_vega}, attrs ->
+        Map.put(attrs, :output_is_vega, output_is_vega)
+
       _entry, attrs ->
         attrs
     end)

From 0b1ff0519c49042588aa36bbdf8db5b96c2a9532 Mon Sep 17 00:00:00 2001
From: Cocoa <89497197+cocoa-xu@users.noreply.github.com>
Date: Thu, 4 Nov 2021 01:31:28 +0000
Subject: [PATCH 02/12] cleanup debug code

---
 lib/livebook/live_markdown/import.ex | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/lib/livebook/live_markdown/import.ex b/lib/livebook/live_markdown/import.ex
index 19c3a8a68eb..89e1645f0fa 100644
--- a/lib/livebook/live_markdown/import.ex
+++ b/lib/livebook/live_markdown/import.ex
@@ -356,9 +356,6 @@ defmodule Livebook.LiveMarkdown.Import do
       {"reevaluate_automatically", reevaluate_automatically}, attrs ->
         Map.put(attrs, :reevaluate_automatically, reevaluate_automatically)
 
-      {"output_is_vega", output_is_vega}, attrs ->
-        Map.put(attrs, :output_is_vega, output_is_vega)
-
       _entry, attrs ->
         attrs
     end)

From c2cf061f88ce32aff98ad567eea860682c07ff0a Mon Sep 17 00:00:00 2001
From: Cocoa <89497197+cocoa-xu@users.noreply.github.com>
Date: Thu, 4 Nov 2021 09:52:45 +0000
Subject: [PATCH 03/12] using `vega-lite` as the type in the fenced code block

---
 lib/livebook/live_markdown/export.ex | 2 +-
 lib/livebook/live_markdown/import.ex | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/livebook/live_markdown/export.ex b/lib/livebook/live_markdown/export.ex
index a8a0d2c6917..cce17ab940c 100644
--- a/lib/livebook/live_markdown/export.ex
+++ b/lib/livebook/live_markdown/export.ex
@@ -154,7 +154,7 @@ defmodule Livebook.LiveMarkdown.Export do
   end
 
   defp render_output({:vega_lite_static, vegalite_data}) do
-    ["```", "vega_lite_static\n", Jason.encode!(vegalite_data), "\n", "```"]
+    ["```", "vega-lite\n", Jason.encode!(vegalite_data), "\n", "```"]
   end
 
   defp render_output(_output), do: :ignored
diff --git a/lib/livebook/live_markdown/import.ex b/lib/livebook/live_markdown/import.ex
index 89e1645f0fa..bc27b2a01fb 100644
--- a/lib/livebook/live_markdown/import.ex
+++ b/lib/livebook/live_markdown/import.ex
@@ -188,7 +188,7 @@ defmodule Livebook.LiveMarkdown.Import do
   end
 
   defp take_outputs(
-         [{"pre", _, [{"code", [{"class", "vega_lite_static"}], [output], %{}}], %{}} | ast],
+         [{"pre", _, [{"code", [{"class", "vega-lite"}], [output], %{}}], %{}} | ast],
          outputs
        ) do
     case Jason.decode(output) do

From f4b3858a2af0c0638918ea3d1662e9f766ef0e73 Mon Sep 17 00:00:00 2001
From: Cocoa <89497197+cocoa-xu@users.noreply.github.com>
Date: Thu, 4 Nov 2021 09:56:02 +0000
Subject: [PATCH 04/12] wrap the text output in `{:text, output}` in
 take_outputs/2

---
 lib/livebook/live_markdown/import.ex | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/lib/livebook/live_markdown/import.ex b/lib/livebook/live_markdown/import.ex
index bc27b2a01fb..843ac177985 100644
--- a/lib/livebook/live_markdown/import.ex
+++ b/lib/livebook/live_markdown/import.ex
@@ -184,7 +184,7 @@ defmodule Livebook.LiveMarkdown.Import do
          [{"pre", _, [{"code", [{"class", "output"}], [output], %{}}], %{}} | ast],
          outputs
        ) do
-    take_outputs(ast, [output | outputs])
+    take_outputs(ast, [{:text, output} | outputs])
   end
 
   defp take_outputs(
@@ -208,7 +208,6 @@ defmodule Livebook.LiveMarkdown.Import do
   defp build_notebook([{:cell, :elixir, source, outputs} | elems], cells, sections, messages) do
     {metadata, elems} = grab_metadata(elems)
     attrs = cell_metadata_to_attrs(:elixir, metadata)
-    outputs = Enum.map(outputs, fn output -> if is_tuple(output), do: output, else: {:text, output} end )
     cell = %{Notebook.Cell.new(:elixir) | source: source, outputs: outputs} |> Map.merge(attrs)
     build_notebook(elems, [cell | cells], sections, messages)
   end

From 5ba6a327538dc388fc80418e9ff768c0357fc8e5 Mon Sep 17 00:00:00 2001
From: Cocoa <89497197+cocoa-xu@users.noreply.github.com>
Date: Thu, 4 Nov 2021 10:39:30 +0000
Subject: [PATCH 05/12] ignore :vega_lite_static when it is empty

---
 lib/livebook/live_markdown/export.ex | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/lib/livebook/live_markdown/export.ex b/lib/livebook/live_markdown/export.ex
index cce17ab940c..041bb132b2c 100644
--- a/lib/livebook/live_markdown/export.ex
+++ b/lib/livebook/live_markdown/export.ex
@@ -153,6 +153,9 @@ defmodule Livebook.LiveMarkdown.Export do
     [delimiter, "output\n", text, "\n", delimiter]
   end
 
+  defp render_output({:vega_lite_static, vegalite_data}) when vegalite_data == %{},
+    do: :ignored
+
   defp render_output({:vega_lite_static, vegalite_data}) do
     ["```", "vega-lite\n", Jason.encode!(vegalite_data), "\n", "```"]
   end

From d2049060c1f2dfa0c84245ed98f9a39708d40744 Mon Sep 17 00:00:00 2001
From: Cocoa <89497197+cocoa-xu@users.noreply.github.com>
Date: Thu, 4 Nov 2021 10:39:51 +0000
Subject: [PATCH 06/12] add import and export tests

---
 test/livebook/live_markdown/export_test.exs | 103 ++++++++++++++++++-
 test/livebook/live_markdown/import_test.exs | 105 ++++++++++++++++++++
 2 files changed, 207 insertions(+), 1 deletion(-)

diff --git a/test/livebook/live_markdown/export_test.exs b/test/livebook/live_markdown/export_test.exs
index 88bd722d5ae..12a93069a54 100644
--- a/test/livebook/live_markdown/export_test.exs
+++ b/test/livebook/live_markdown/export_test.exs
@@ -650,7 +650,7 @@ defmodule Livebook.LiveMarkdown.ExportTest do
                     | source: """
                       IO.puts("hey")\
                       """,
-                      outputs: [{:vega_lite_static, %{}}, {:table_dynamic, self()}]
+                      outputs: [{:table_dynamic, self()}]
                   }
                 ]
             }
@@ -671,6 +671,107 @@ defmodule Livebook.LiveMarkdown.ExportTest do
 
       assert expected_document == document
     end
+
+    test "includes empty vega_lite_static output" do
+      notebook = %{
+        Notebook.new()
+        | name: "My Notebook",
+          sections: [
+            %{
+              Notebook.Section.new()
+              | name: "Section 1",
+                cells: [
+                  %{
+                    Notebook.Cell.new(:elixir)
+                    | source: """
+                      IO.puts("hey")\
+                      """,
+                      outputs: [{:vega_lite_static, %{}}]
+                  }
+                ]
+            }
+          ]
+      }
+
+      expected_document = """
+      # My Notebook
+
+      ## Section 1
+
+      ```elixir
+      IO.puts("hey")
+      ```
+      """
+
+      document = Export.notebook_to_markdown(notebook, include_outputs: true)
+
+      assert expected_document == document
+    end
+
+    test "includes non-empty vega_lite_static output" do
+      notebook = %{
+        Notebook.new()
+        | name: "My Notebook",
+          sections: [
+            %{
+              Notebook.Section.new()
+              | name: "Section 1",
+                cells: [
+                  %{
+                    Notebook.Cell.new(:elixir)
+                    | source: """
+                      Vl.new(width: 500, height: 200)
+                      |> Vl.data_from_series(in: [1, 2, 3, 4, 5], out: [1, 2, 3, 4, 5])
+                      |> Vl.mark(:line)
+                      |> Vl.encode_field(:x, "in", type: :quantitative)
+                      |> Vl.encode_field(:y, "out", type: :quantitative)\
+                      """,
+                      outputs: [{:vega_lite_static, %{
+                        "$schema" => "https://vega.github.io/schema/vega-lite/v5.json",
+                        "data" => %{
+                          "values" => [
+                            %{"in" => 1, "out" => 1},
+                            %{"in" => 2, "out" => 2},
+                            %{"in" => 3, "out" => 3},
+                            %{"in" => 4, "out" => 4},
+                            %{"in" => 5, "out" => 5}]
+                        },
+                        "encoding" => %{
+                          "x" => %{"field" => "in", "type" => "quantitative"},
+                          "y" => %{"field" => "out", "type" => "quantitative"}
+                        },
+                        "height" => 200,
+                        "mark" => "line",
+                        "width" => 500
+                      }}]
+                  }
+                ]
+            }
+          ]
+      }
+
+      expected_document = """
+      # My Notebook
+
+      ## Section 1
+
+      ```elixir
+      Vl.new(width: 500, height: 200)
+      |> Vl.data_from_series(in: [1, 2, 3, 4, 5], out: [1, 2, 3, 4, 5])
+      |> Vl.mark(:line)
+      |> Vl.encode_field(:x, "in", type: :quantitative)
+      |> Vl.encode_field(:y, "out", type: :quantitative)
+      ```
+
+      ```vega-lite
+      {"$schema":"https://vega.github.io/schema/vega-lite/v5.json","data":{"values":[{"in":1,"out":1},{"in":2,"out":2},{"in":3,"out":3},{"in":4,"out":4},{"in":5,"out":5}]},"encoding":{"x":{"field":"in","type":"quantitative"},"y":{"field":"out","type":"quantitative"}},"height":200,"mark":"line","width":500}
+      ```
+      """
+
+      document = Export.notebook_to_markdown(notebook, include_outputs: true)
+
+      assert expected_document == document
+    end
   end
 
   test "includes outputs when notebook has :persist_outputs set" do
diff --git a/test/livebook/live_markdown/import_test.exs b/test/livebook/live_markdown/import_test.exs
index b803337a4be..1610d131927 100644
--- a/test/livebook/live_markdown/import_test.exs
+++ b/test/livebook/live_markdown/import_test.exs
@@ -582,6 +582,111 @@ defmodule Livebook.LiveMarkdown.ImportTest do
     assert %Notebook{name: "My Notebook", autosave_interval_s: 10} = notebook
   end
 
+  test "imports notebook with valid vega-lite output" do
+    markdown = """
+    # My Notebook
+
+    ## Section 1
+
+    ```elixir
+    Vl.new(width: 500, height: 200)
+    |> Vl.data_from_series(in: [1, 2, 3, 4, 5], out: [1, 2, 3, 4, 5])
+    |> Vl.mark(:line)
+    |> Vl.encode_field(:x, "in", type: :quantitative)
+    |> Vl.encode_field(:y, "out", type: :quantitative)
+    ```
+
+    ```vega-lite
+    {"$schema":"https://vega.github.io/schema/vega-lite/v5.json","data":{"values":[{"in":1,"out":1},{"in":2,"out":2},{"in":3,"out":3},{"in":4,"out":4},{"in":5,"out":5}]},"encoding":{"x":{"field":"in","type":"quantitative"},"y":{"field":"out","type":"quantitative"}},"height":200,"mark":"line","width":500}
+    ```
+    """
+
+    {notebook, []} = Import.notebook_from_markdown(markdown)
+
+    assert %Notebook{
+      name: "My Notebook",
+      sections: [
+        %Notebook.Section{
+          name: "Section 1",
+          cells: [
+            %Cell.Elixir{
+              source: """
+              Vl.new(width: 500, height: 200)
+              |> Vl.data_from_series(in: [1, 2, 3, 4, 5], out: [1, 2, 3, 4, 5])
+              |> Vl.mark(:line)
+              |> Vl.encode_field(:x, \"in\", type: :quantitative)
+              |> Vl.encode_field(:y, \"out\", type: :quantitative)\
+              """,
+              outputs: [
+                vega_lite_static: %{
+                  "$schema" => "https://vega.github.io/schema/vega-lite/v5.json",
+                  "data" => %{
+                    "values" => [
+                      %{"in" => 1, "out" => 1},
+                      %{"in" => 2, "out" => 2},
+                      %{"in" => 3, "out" => 3},
+                      %{"in" => 4, "out" => 4},
+                      %{"in" => 5, "out" => 5}]
+                  },
+                  "encoding" => %{
+                    "x" => %{"field" => "in", "type" => "quantitative"},
+                    "y" => %{"field" => "out", "type" => "quantitative"}
+                  },
+                  "height" => 200,
+                  "mark" => "line",
+                  "width" => 500
+                }
+              ]
+            }
+          ]
+        }
+      ]
+    } = notebook
+  end
+
+  test "imports notebook with invalid vega-lite output" do
+    markdown = """
+    # My Notebook
+
+    ## Section 1
+
+    ```elixir
+    Vl.new(width: 500, height: 200)
+    |> Vl.data_from_series(in: [1, 2, 3, 4, 5], out: [1, 2, 3, 4, 5])
+    |> Vl.mark(:line)
+    |> Vl.encode_field(:x, "in", type: :quantitative)
+    |> Vl.encode_field(:y, "out", type: :quantitative)
+    ```
+
+    ```vega-lite
+    "$schema":"https://vega.github.io/schema/vega-lite/v5.json","data":{"values":[{"in":1,"out":1},{"in":2,"out":2},{"in":3,"out":3},{"in":4,"out":4},{"in":5,"out":5}]},"encoding":{"x":{"field":"in","type":"quantitative"},"y":{"field":"out","type":"quantitative"}},"height":200,"mark":"line","width":500}
+    ```
+    """
+
+    {notebook, []} = Import.notebook_from_markdown(markdown)
+
+    assert %Notebook{
+      name: "My Notebook",
+      sections: [
+        %Notebook.Section{
+          name: "Section 1",
+          cells: [
+            %Cell.Elixir{
+              source: """
+              Vl.new(width: 500, height: 200)
+              |> Vl.data_from_series(in: [1, 2, 3, 4, 5], out: [1, 2, 3, 4, 5])
+              |> Vl.mark(:line)
+              |> Vl.encode_field(:x, \"in\", type: :quantitative)
+              |> Vl.encode_field(:y, \"out\", type: :quantitative)\
+              """,
+              outputs: []
+            }
+          ]
+        }
+      ]
+    } = notebook
+  end
+
   test "skips invalid input type and returns a message" do
     markdown = """
     # My Notebook

From 8a8d2a359873bd4409efc2b24ef948d45c0c4f78 Mon Sep 17 00:00:00 2001
From: Cocoa <89497197+cocoa-xu@users.noreply.github.com>
Date: Thu, 4 Nov 2021 10:50:13 +0000
Subject: [PATCH 07/12] using `spec`

---
 lib/livebook/live_markdown/export.ex | 6 +++---
 lib/livebook/live_markdown/import.ex | 2 +-
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/lib/livebook/live_markdown/export.ex b/lib/livebook/live_markdown/export.ex
index 041bb132b2c..4c1281aa256 100644
--- a/lib/livebook/live_markdown/export.ex
+++ b/lib/livebook/live_markdown/export.ex
@@ -153,11 +153,11 @@ defmodule Livebook.LiveMarkdown.Export do
     [delimiter, "output\n", text, "\n", delimiter]
   end
 
-  defp render_output({:vega_lite_static, vegalite_data}) when vegalite_data == %{},
+  defp render_output({:vega_lite_static, spec}) when spec == %{},
     do: :ignored
 
-  defp render_output({:vega_lite_static, vegalite_data}) do
-    ["```", "vega-lite\n", Jason.encode!(vegalite_data), "\n", "```"]
+  defp render_output({:vega_lite_static, spec}) do
+    ["```", "vega-lite\n", Jason.encode!(spec), "\n", "```"]
   end
 
   defp render_output(_output), do: :ignored
diff --git a/lib/livebook/live_markdown/import.ex b/lib/livebook/live_markdown/import.ex
index 843ac177985..8ac9431c91e 100644
--- a/lib/livebook/live_markdown/import.ex
+++ b/lib/livebook/live_markdown/import.ex
@@ -192,7 +192,7 @@ defmodule Livebook.LiveMarkdown.Import do
          outputs
        ) do
     case Jason.decode(output) do
-      {:ok, data} -> take_outputs(ast, [{:vega_lite_static, data} | outputs])
+      {:ok, spec} -> take_outputs(ast, [{:vega_lite_static, spec} | outputs])
       _ -> take_outputs(ast, outputs)
     end
   end

From 09f08936507dfd5e34161b8b1a8ce1d62dd72317 Mon Sep 17 00:00:00 2001
From: Cocoa <89497197+cocoa-xu@users.noreply.github.com>
Date: Thu, 4 Nov 2021 10:50:26 +0000
Subject: [PATCH 08/12] format code

---
 test/livebook/live_markdown/export_test.exs |  40 ++++---
 test/livebook/live_markdown/import_test.exs | 115 ++++++++++----------
 2 files changed, 80 insertions(+), 75 deletions(-)

diff --git a/test/livebook/live_markdown/export_test.exs b/test/livebook/live_markdown/export_test.exs
index 12a93069a54..735b635f61c 100644
--- a/test/livebook/live_markdown/export_test.exs
+++ b/test/livebook/live_markdown/export_test.exs
@@ -726,24 +726,28 @@ defmodule Livebook.LiveMarkdown.ExportTest do
                       |> Vl.encode_field(:x, "in", type: :quantitative)
                       |> Vl.encode_field(:y, "out", type: :quantitative)\
                       """,
-                      outputs: [{:vega_lite_static, %{
-                        "$schema" => "https://vega.github.io/schema/vega-lite/v5.json",
-                        "data" => %{
-                          "values" => [
-                            %{"in" => 1, "out" => 1},
-                            %{"in" => 2, "out" => 2},
-                            %{"in" => 3, "out" => 3},
-                            %{"in" => 4, "out" => 4},
-                            %{"in" => 5, "out" => 5}]
-                        },
-                        "encoding" => %{
-                          "x" => %{"field" => "in", "type" => "quantitative"},
-                          "y" => %{"field" => "out", "type" => "quantitative"}
-                        },
-                        "height" => 200,
-                        "mark" => "line",
-                        "width" => 500
-                      }}]
+                      outputs: [
+                        {:vega_lite_static,
+                         %{
+                           "$schema" => "https://vega.github.io/schema/vega-lite/v5.json",
+                           "data" => %{
+                             "values" => [
+                               %{"in" => 1, "out" => 1},
+                               %{"in" => 2, "out" => 2},
+                               %{"in" => 3, "out" => 3},
+                               %{"in" => 4, "out" => 4},
+                               %{"in" => 5, "out" => 5}
+                             ]
+                           },
+                           "encoding" => %{
+                             "x" => %{"field" => "in", "type" => "quantitative"},
+                             "y" => %{"field" => "out", "type" => "quantitative"}
+                           },
+                           "height" => 200,
+                           "mark" => "line",
+                           "width" => 500
+                         }}
+                      ]
                   }
                 ]
             }
diff --git a/test/livebook/live_markdown/import_test.exs b/test/livebook/live_markdown/import_test.exs
index 1610d131927..31c146d072a 100644
--- a/test/livebook/live_markdown/import_test.exs
+++ b/test/livebook/live_markdown/import_test.exs
@@ -604,44 +604,45 @@ defmodule Livebook.LiveMarkdown.ImportTest do
     {notebook, []} = Import.notebook_from_markdown(markdown)
 
     assert %Notebook{
-      name: "My Notebook",
-      sections: [
-        %Notebook.Section{
-          name: "Section 1",
-          cells: [
-            %Cell.Elixir{
-              source: """
-              Vl.new(width: 500, height: 200)
-              |> Vl.data_from_series(in: [1, 2, 3, 4, 5], out: [1, 2, 3, 4, 5])
-              |> Vl.mark(:line)
-              |> Vl.encode_field(:x, \"in\", type: :quantitative)
-              |> Vl.encode_field(:y, \"out\", type: :quantitative)\
-              """,
-              outputs: [
-                vega_lite_static: %{
-                  "$schema" => "https://vega.github.io/schema/vega-lite/v5.json",
-                  "data" => %{
-                    "values" => [
-                      %{"in" => 1, "out" => 1},
-                      %{"in" => 2, "out" => 2},
-                      %{"in" => 3, "out" => 3},
-                      %{"in" => 4, "out" => 4},
-                      %{"in" => 5, "out" => 5}]
-                  },
-                  "encoding" => %{
-                    "x" => %{"field" => "in", "type" => "quantitative"},
-                    "y" => %{"field" => "out", "type" => "quantitative"}
-                  },
-                  "height" => 200,
-                  "mark" => "line",
-                  "width" => 500
-                }
-              ]
-            }
-          ]
-        }
-      ]
-    } = notebook
+             name: "My Notebook",
+             sections: [
+               %Notebook.Section{
+                 name: "Section 1",
+                 cells: [
+                   %Cell.Elixir{
+                     source: """
+                     Vl.new(width: 500, height: 200)
+                     |> Vl.data_from_series(in: [1, 2, 3, 4, 5], out: [1, 2, 3, 4, 5])
+                     |> Vl.mark(:line)
+                     |> Vl.encode_field(:x, \"in\", type: :quantitative)
+                     |> Vl.encode_field(:y, \"out\", type: :quantitative)\
+                     """,
+                     outputs: [
+                       vega_lite_static: %{
+                         "$schema" => "https://vega.github.io/schema/vega-lite/v5.json",
+                         "data" => %{
+                           "values" => [
+                             %{"in" => 1, "out" => 1},
+                             %{"in" => 2, "out" => 2},
+                             %{"in" => 3, "out" => 3},
+                             %{"in" => 4, "out" => 4},
+                             %{"in" => 5, "out" => 5}
+                           ]
+                         },
+                         "encoding" => %{
+                           "x" => %{"field" => "in", "type" => "quantitative"},
+                           "y" => %{"field" => "out", "type" => "quantitative"}
+                         },
+                         "height" => 200,
+                         "mark" => "line",
+                         "width" => 500
+                       }
+                     ]
+                   }
+                 ]
+               }
+             ]
+           } = notebook
   end
 
   test "imports notebook with invalid vega-lite output" do
@@ -666,25 +667,25 @@ defmodule Livebook.LiveMarkdown.ImportTest do
     {notebook, []} = Import.notebook_from_markdown(markdown)
 
     assert %Notebook{
-      name: "My Notebook",
-      sections: [
-        %Notebook.Section{
-          name: "Section 1",
-          cells: [
-            %Cell.Elixir{
-              source: """
-              Vl.new(width: 500, height: 200)
-              |> Vl.data_from_series(in: [1, 2, 3, 4, 5], out: [1, 2, 3, 4, 5])
-              |> Vl.mark(:line)
-              |> Vl.encode_field(:x, \"in\", type: :quantitative)
-              |> Vl.encode_field(:y, \"out\", type: :quantitative)\
-              """,
-              outputs: []
-            }
-          ]
-        }
-      ]
-    } = notebook
+             name: "My Notebook",
+             sections: [
+               %Notebook.Section{
+                 name: "Section 1",
+                 cells: [
+                   %Cell.Elixir{
+                     source: """
+                     Vl.new(width: 500, height: 200)
+                     |> Vl.data_from_series(in: [1, 2, 3, 4, 5], out: [1, 2, 3, 4, 5])
+                     |> Vl.mark(:line)
+                     |> Vl.encode_field(:x, \"in\", type: :quantitative)
+                     |> Vl.encode_field(:y, \"out\", type: :quantitative)\
+                     """,
+                     outputs: []
+                   }
+                 ]
+               }
+             ]
+           } = notebook
   end
 
   test "skips invalid input type and returns a message" do

From 057dad75926a4b25209a60ac8f088c413167b6e6 Mon Sep 17 00:00:00 2001
From: Cocoa <89497197+cocoa-xu@users.noreply.github.com>
Date: Thu, 4 Nov 2021 11:04:17 +0000
Subject: [PATCH 09/12] keep the test focused

---
 test/livebook/live_markdown/import_test.exs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/test/livebook/live_markdown/import_test.exs b/test/livebook/live_markdown/import_test.exs
index 31c146d072a..252911a3031 100644
--- a/test/livebook/live_markdown/import_test.exs
+++ b/test/livebook/live_markdown/import_test.exs
@@ -660,7 +660,7 @@ defmodule Livebook.LiveMarkdown.ImportTest do
     ```
 
     ```vega-lite
-    "$schema":"https://vega.github.io/schema/vega-lite/v5.json","data":{"values":[{"in":1,"out":1},{"in":2,"out":2},{"in":3,"out":3},{"in":4,"out":4},{"in":5,"out":5}]},"encoding":{"x":{"field":"in","type":"quantitative"},"y":{"field":"out","type":"quantitative"}},"height":200,"mark":"line","width":500}
+    not_a_json
     ```
     """
 

From 8ff8d246992499af163be74ce3a47d3f633883d7 Mon Sep 17 00:00:00 2001
From: Cocoa <89497197+cocoa-xu@users.noreply.github.com>
Date: Thu, 4 Nov 2021 11:10:03 +0000
Subject: [PATCH 10/12] improve tests for not including outputs

---
 test/livebook/live_markdown/export_test.exs | 44 ++++-----------------
 1 file changed, 7 insertions(+), 37 deletions(-)

diff --git a/test/livebook/live_markdown/export_test.exs b/test/livebook/live_markdown/export_test.exs
index 735b635f61c..79aac52c2e1 100644
--- a/test/livebook/live_markdown/export_test.exs
+++ b/test/livebook/live_markdown/export_test.exs
@@ -530,7 +530,13 @@ defmodule Livebook.LiveMarkdown.ExportTest do
                     | source: """
                       IO.puts("hey")\
                       """,
-                      outputs: ["hey"]
+                      outputs: [
+                        "hey",
+                        {:vega_lite_static,
+                         %{
+                           "$schema" => "https://vega.github.io/schema/vega-lite/v5.json"
+                         }}
+                      ]
                   }
                 ]
             }
@@ -672,42 +678,6 @@ defmodule Livebook.LiveMarkdown.ExportTest do
       assert expected_document == document
     end
 
-    test "includes empty vega_lite_static output" do
-      notebook = %{
-        Notebook.new()
-        | name: "My Notebook",
-          sections: [
-            %{
-              Notebook.Section.new()
-              | name: "Section 1",
-                cells: [
-                  %{
-                    Notebook.Cell.new(:elixir)
-                    | source: """
-                      IO.puts("hey")\
-                      """,
-                      outputs: [{:vega_lite_static, %{}}]
-                  }
-                ]
-            }
-          ]
-      }
-
-      expected_document = """
-      # My Notebook
-
-      ## Section 1
-
-      ```elixir
-      IO.puts("hey")
-      ```
-      """
-
-      document = Export.notebook_to_markdown(notebook, include_outputs: true)
-
-      assert expected_document == document
-    end
-
     test "includes non-empty vega_lite_static output" do
       notebook = %{
         Notebook.new()

From bebdd2d71ec30dd338ec015470d7d7bf1d162156 Mon Sep 17 00:00:00 2001
From: Cocoa <89497197+cocoa-xu@users.noreply.github.com>
Date: Thu, 4 Nov 2021 11:10:44 +0000
Subject: [PATCH 11/12] always dump vage_lite spec

---
 lib/livebook/live_markdown/export.ex | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/lib/livebook/live_markdown/export.ex b/lib/livebook/live_markdown/export.ex
index 4c1281aa256..660c9a0ff7d 100644
--- a/lib/livebook/live_markdown/export.ex
+++ b/lib/livebook/live_markdown/export.ex
@@ -153,9 +153,6 @@ defmodule Livebook.LiveMarkdown.Export do
     [delimiter, "output\n", text, "\n", delimiter]
   end
 
-  defp render_output({:vega_lite_static, spec}) when spec == %{},
-    do: :ignored
-
   defp render_output({:vega_lite_static, spec}) do
     ["```", "vega-lite\n", Jason.encode!(spec), "\n", "```"]
   end

From e42c90c37d691205a9f431df1627a811a8f1be91 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jonatan=20K=C5=82osko?= <jonatanklosko@gmail.com>
Date: Thu, 4 Nov 2021 12:15:07 +0100
Subject: [PATCH 12/12] Apply suggestions from code review

---
 test/livebook/live_markdown/export_test.exs |  2 +-
 test/livebook/live_markdown/import_test.exs | 12 ++----------
 2 files changed, 3 insertions(+), 11 deletions(-)

diff --git a/test/livebook/live_markdown/export_test.exs b/test/livebook/live_markdown/export_test.exs
index 79aac52c2e1..7bf2b78ce90 100644
--- a/test/livebook/live_markdown/export_test.exs
+++ b/test/livebook/live_markdown/export_test.exs
@@ -678,7 +678,7 @@ defmodule Livebook.LiveMarkdown.ExportTest do
       assert expected_document == document
     end
 
-    test "includes non-empty vega_lite_static output" do
+    test "includes vega_lite_static output" do
       notebook = %{
         Notebook.new()
         | name: "My Notebook",
diff --git a/test/livebook/live_markdown/import_test.exs b/test/livebook/live_markdown/import_test.exs
index 252911a3031..d1a75aea246 100644
--- a/test/livebook/live_markdown/import_test.exs
+++ b/test/livebook/live_markdown/import_test.exs
@@ -652,11 +652,7 @@ defmodule Livebook.LiveMarkdown.ImportTest do
     ## Section 1
 
     ```elixir
-    Vl.new(width: 500, height: 200)
-    |> Vl.data_from_series(in: [1, 2, 3, 4, 5], out: [1, 2, 3, 4, 5])
-    |> Vl.mark(:line)
-    |> Vl.encode_field(:x, "in", type: :quantitative)
-    |> Vl.encode_field(:y, "out", type: :quantitative)
+    :ok
     ```
 
     ```vega-lite
@@ -674,11 +670,7 @@ defmodule Livebook.LiveMarkdown.ImportTest do
                  cells: [
                    %Cell.Elixir{
                      source: """
-                     Vl.new(width: 500, height: 200)
-                     |> Vl.data_from_series(in: [1, 2, 3, 4, 5], out: [1, 2, 3, 4, 5])
-                     |> Vl.mark(:line)
-                     |> Vl.encode_field(:x, \"in\", type: :quantitative)
-                     |> Vl.encode_field(:y, \"out\", type: :quantitative)\
+                     :ok\
                      """,
                      outputs: []
                    }