Preserve numeric 0 in YAML directive options

src/directives/main.ts

@@ -294,7 +294,7 @@ export function parseDirectiveOptions(
       // In docutils all values are simply read as strings,
       // but loading with YAML these can be converted to other types, so we convert them back first
       // TODO check that it is sufficient to simply do this conversion, or if there is a better way
-      converted_value = convertor(`${converted_value || ""}`)
+      converted_value = convertor(`${converted_value ?? ""}`)
     } catch (error) {
       throw new DirectiveParsingError(
         `Invalid option value: (option: '${name}'; value: ${value})\n${error}`

tests/listTableHeaderRows.spec.ts

@@ -0,0 +1,92 @@
+import MarkdownIt from "markdown-it"
+import docutils_plugin from "../src"
+import { parseDirectiveOptions } from "../src/directives/main"
+import { nonnegative_int, unchanged } from "../src/directives/options"
+
+function render(src: string): string {
+  return MarkdownIt().use(docutils_plugin).render(src)
+}
+
+const listTableBody = `*   - A
+    - B
+*   - C
+    - D`
+
+describe("list-table header-rows: 0 is a valid value", () => {
+  it("YAML option block header-rows: 0 must not throw OptionSpecError / Value is not set", () => {
+    const html = render(`\`\`\`{list-table}
+---
+header-rows: 0
+---
+${listTableBody}
+\`\`\``)
+    expect(html).not.toMatch(/OptionSpecError/)
+    expect(html).not.toMatch(/Value is not set/)
+    expect(html).not.toMatch(/directive-error/)
+    expect(html).toContain("<table>")
+    expect(html).not.toContain("<thead>")
+    expect(html).toContain("<tbody>")
+    expect(html).toContain("<td>A</td>")
+  })
+
+  it("colon form :header-rows: 0 must also accept numeric 0", () => {
+    const html = render(`\`\`\`{list-table}
+:header-rows: 0
+
+${listTableBody}
+\`\`\``)
+    expect(html).not.toMatch(/OptionSpecError/)
+    expect(html).not.toMatch(/Value is not set/)
+    expect(html).not.toMatch(/directive-error/)
+    expect(html).toContain("<table>")
+    expect(html).not.toContain("<thead>")
+    expect(html).toContain("<tbody>")
+    expect(html).toContain("<td>A</td>")
+  })
+
+  it("header-rows: 1 must still work (thead present)", () => {
+    const html = render(`\`\`\`{list-table}
+:header-rows: 1
+
+${listTableBody}
+\`\`\``)
+    expect(html).not.toMatch(/directive-error/)
+    expect(html).toContain("<thead>")
+    expect(html).toContain("<th>A</th>")
+    expect(html).toContain("<tbody>")
+    expect(html).toContain("<td>C</td>")
+  })
+})
+
+describe("parseDirectiveOptions preserves numeric 0", () => {
+  const spec = { option_spec: { "header-rows": nonnegative_int } }
+
+  it("YAML header-rows: 0 converts to number 0, not empty string", () => {
+    const [, options] = parseDirectiveOptions(["---", "header-rows: 0", "---"], spec)
+    expect(options["header-rows"]).toBe(0)
+  })
+
+  it("colon :header-rows: 0 converts to number 0 (yaml.load yields 0)", () => {
+    const [, options] = parseDirectiveOptions([":header-rows: 0"], spec)
+    expect(options["header-rows"]).toBe(0)
+  })
+
+  it("header-rows: 1 still converts to number 1", () => {
+    const [, options] = parseDirectiveOptions([":header-rows: 1"], spec)
+    expect(options["header-rows"]).toBe(1)
+  })
+
+  it("null option values still become empty string before convertor", () => {
+    const [, options] = parseDirectiveOptions(["---", "a:", "---"], {
+      option_spec: { a: unchanged }
+    })
+    expect(options.a).toBe("")
+  })
+
+  it("false option values still become empty string before convertor", () => {
+    const [, options] = parseDirectiveOptions(["---", "a: false", "---"], {
+      option_spec: { a: unchanged }
+    })
+    expect(options.a).toBe("")
+  })
+})