fix(shell): Empty messages were getting sent when hitting enter over and over again in the prompt. (#1819)

Author: joeyguerra

src/adapters/Shell.mjs

@@ -103,6 +103,10 @@ class Shell extends Adapter {
           this.#rl.prompt()
           break
       }
+      if (input.length === 0) {
+        this.#rl.prompt()
+        return
+      }
       if (input.length > 0) {
         this.#rl.history.push(input)
       }

test/Shell_test.mjs

@@ -75,6 +75,28 @@ describe('Shell Adapter Integration Test', () => {
     await new Promise(resolve => setTimeout(resolve, 60))
     assert.deepEqual(wasCalled, false)
   })
+  it('shows prompt if only spaces were entered', async () => {
+    let wasCalled = false
+    robot.respond(/.*/, async res => {
+      wasCalled = true
+      await res.reply('hello from the other side')
+    })
+    robot.stdin.push('   \n')
+    robot.stdin.push(null)
+    await new Promise(resolve => setTimeout(resolve, 60))
+    assert.deepEqual(wasCalled, false)
+  })
+  it('shows prompt if only tabs were entered', async () => {
+    let wasCalled = false
+    robot.respond(/.*/, async res => {
+      wasCalled = true
+      await res.reply('hello from the other side')
+    })
+    robot.stdin.push('\t\t\n')
+    robot.stdin.push(null)
+    await new Promise(resolve => setTimeout(resolve, 60))
+    assert.deepEqual(wasCalled, false)
+  })
 })
 
 describe('Shell Adapter', () => {