Test and fix conversion of empty parts (#1675)

* Test and fix conversion of empty parts

* Cover case of last part empty

6 files changed, 212 insertions, 8 deletions

diff --git a/packages/gitbook/src/modifiers/summary/__tests__/fixtures/empty-part.yaml b/packages/gitbook/src/modifiers/summary/__tests__/fixtures/empty-part.yaml
new file mode 100644
index 0000000..de11664
--- /dev/null
+++ b/packages/gitbook/src/modifiers/summary/__tests__/fixtures/empty-part.yaml
@@ -0,0 +1,58 @@
+nodes:
+  - kind: block
+    type: header_one
+    nodes:
+      - kind: text
+        text: Summary
+
+  - kind: block
+    type: header_two
+    nodes:
+      - kind: text
+        text: 'Part 1'
+  - kind: block
+    type: unordered_list
+    nodes:
+      - kind: block
+        type: list_item
+        nodes:
+          - kind: block
+            type: unstyled
+            nodes:
+              - kind: text
+                text: 'Article 1'
+
+  - kind: block
+    type: header_two
+    nodes:
+      - kind: text
+        text: 'Empty part 1'
+
+  - kind: block
+    type: header_two
+    nodes:
+      - kind: text
+        text: 'Empty part 2'
+
+  - kind: block
+    type: header_two
+    nodes:
+      - kind: text
+        text: 'Part 2'
+  - kind: block
+    type: unordered_list
+    nodes:
+      - kind: block
+        type: list_item
+        nodes:
+          - kind: block
+            type: unstyled
+            nodes:
+              - kind: text
+                text: 'Article 2'
+
+  - kind: block
+    type: header_two
+    nodes:
+      - kind: text
+        text: 'Empty part 3'
diff --git a/packages/gitbook/src/modifiers/summary/__tests__/toDocument.js b/packages/gitbook/src/modifiers/summary/__tests__/toDocument.js
index 93e8124..0252103 100644
--- a/packages/gitbook/src/modifiers/summary/__tests__/toDocument.js
+++ b/packages/gitbook/src/modifiers/summary/__tests__/toDocument.js
@@ -106,6 +106,39 @@ describe('summaryToDocument', () => {
         ]);
     });
 
+    it('should convert empty parts', () => {
+        expectDocument('empty-part.yaml', [
+            {
+                title: 'Part 1',
+                articles: [
+                    {
+                        title: 'Article 1'
+                    }
+                ]
+            },
+            {
+                title: 'Empty part 1',
+                articles: []
+            },
+            {
+                title: 'Empty part 2',
+                articles: []
+            },
+            {
+                title: 'Part 2',
+                articles: [
+                    {
+                        title: 'Article 2'
+                    }
+                ]
+            },
+            {
+                title: 'Empty part 3',
+                articles: []
+            }
+        ]);
+    });
+
     it('should convert a deep summary', () => {
         expectDocument('deep.yaml', [
             {
diff --git a/packages/gitbook/src/modifiers/summary/toDocument.js b/packages/gitbook/src/modifiers/summary/toDocument.js
index 7cd459a..cecc208 100644
--- a/packages/gitbook/src/modifiers/summary/toDocument.js
+++ b/packages/gitbook/src/modifiers/summary/toDocument.js
@@ -85,7 +85,9 @@ function summaryToDocument(summary) {
             }));
         }
 
-        nodes.push(articlesToBlock(articles));
+        if (!articles.isEmpty()) {
+            nodes.push(articlesToBlock(articles));
+        }
     });
 
     return Document.create({ nodes });
diff --git a/packages/gitbook/src/parse/__tests__/fixtures/summary/empty-part.yaml b/packages/gitbook/src/parse/__tests__/fixtures/summary/empty-part.yaml
new file mode 100644
index 0000000..de11664
--- /dev/null
+++ b/packages/gitbook/src/parse/__tests__/fixtures/summary/empty-part.yaml
@@ -0,0 +1,58 @@
+nodes:
+  - kind: block
+    type: header_one
+    nodes:
+      - kind: text
+        text: Summary
+
+  - kind: block
+    type: header_two
+    nodes:
+      - kind: text
+        text: 'Part 1'
+  - kind: block
+    type: unordered_list
+    nodes:
+      - kind: block
+        type: list_item
+        nodes:
+          - kind: block
+            type: unstyled
+            nodes:
+              - kind: text
+                text: 'Article 1'
+
+  - kind: block
+    type: header_two
+    nodes:
+      - kind: text
+        text: 'Empty part 1'
+
+  - kind: block
+    type: header_two
+    nodes:
+      - kind: text
+        text: 'Empty part 2'
+
+  - kind: block
+    type: header_two
+    nodes:
+      - kind: text
+        text: 'Part 2'
+  - kind: block
+    type: unordered_list
+    nodes:
+      - kind: block
+        type: list_item
+        nodes:
+          - kind: block
+            type: unstyled
+            nodes:
+              - kind: text
+                text: 'Article 2'
+
+  - kind: block
+    type: header_two
+    nodes:
+      - kind: text
+        text: 'Empty part 3'
diff --git a/packages/gitbook/src/parse/__tests__/summaryFromDocument.js b/packages/gitbook/src/parse/__tests__/summaryFromDocument.js
index 5ec964d..1714f26 100644
--- a/packages/gitbook/src/parse/__tests__/summaryFromDocument.js
+++ b/packages/gitbook/src/parse/__tests__/summaryFromDocument.js
@@ -112,6 +112,41 @@ describe('summaryFromDocument', () => {
         ]);
     });
 
+    it('should parse empty parts', () => {
+        const summary = readSummary('summary/empty-part.yaml');
+
+        expectParts(summary, [
+            {
+                title: 'Part 1',
+                articles: [
+                    {
+                        title: 'Article 1'
+                    }
+                ]
+            },
+            {
+                title: 'Empty part 1',
+                articles: []
+            },
+            {
+                title: 'Empty part 2',
+                articles: []
+            },
+            {
+                title: 'Part 2',
+                articles: [
+                    {
+                        title: 'Article 2'
+                    }
+                ]
+            },
+            {
+                title: 'Empty part 3',
+                articles: []
+            }
+        ]);
+    });
+
     it('should parse an deep summary', () => {
         const summary = readSummary('summary/deep.yaml');
 
diff --git a/packages/gitbook/src/parse/summaryFromDocument.js b/packages/gitbook/src/parse/summaryFromDocument.js
index 8b35897..1ce14b8 100644
--- a/packages/gitbook/src/parse/summaryFromDocument.js
+++ b/packages/gitbook/src/parse/summaryFromDocument.js
@@ -46,7 +46,9 @@ function listArticles(list) {
 function listParts(document) {
     const { nodes } = document;
     const parts = [];
-    let title = '';
+
+    // Keep a reference to a part, waiting for its articles
+    let pendingPart;
 
     nodes.forEach((node) => {
         const isHeading = (
@@ -55,20 +57,36 @@ function listParts(document) {
         );
 
         if (isHeading) {
-            title = node.text;
+            if (pendingPart) {
+                // The previous was empty
+                parts.push(pendingPart);
+            }
+            pendingPart = {
+                title: node.text
+            };
         }
 
         if (isList(node)) {
             const articles = listArticles(node);
-            parts.push({
-                title,
-                articles
-            });
 
-            title = '';
+            if (pendingPart) {
+                pendingPart.articles = articles;
+                parts.push(pendingPart);
+                pendingPart = undefined;
+            } else {
+                parts.push({
+                    title: '',
+                    articles
+                });
+            }
         }
     });
 
+    if (pendingPart) {
+        // The last one was empty
+        parts.push(pendingPart);
+    }
+
     return List(parts);
 }