summary: method to clear file and buffer

__tests__/markdown-summary.test.ts

@@ -151,6 +151,13 @@ describe('@actions/core/src/markdown-summary', () => {
     expect(markdownSummary.isEmptyBuffer()).toBe(true)
   })
 
+  it('clears a buffer and summary file', async () => {
+    await fs.promises.writeFile(testFilePath, 'content', {encoding: 'utf8'})
+    await markdownSummary.clear()
+    await assertSummary('')
+    expect(markdownSummary.isEmptyBuffer()).toBe(true)
+  })
+
   it('adds EOL', async () => {
     await markdownSummary
       .addRaw(fixtures.text)

src/markdown-summary.ts

@@ -151,6 +151,15 @@ class MarkdownSummary {
     return this.emptyBuffer()
   }
 
+  /**
+   * Clears the summary buffer and wipes the summary file
+   *
+   * @returns {MarkdownSummary} markdown summary instance
+   */
+  async clear(): Promise<MarkdownSummary> {
+    return this.emptyBuffer().write(true)
+  }
+
   /**
    * Returns the current summary buffer as a string
    *
@@ -170,7 +179,7 @@ class MarkdownSummary {
   }
 
   /**
-   * Clears the summary buffer without writing to summary file
+   * Resets the summary buffer without writing to summary file
    *
    * @returns {MarkdownSummary} markdown summary instance
    */