#415: fee() must validate that tab is non-empty

lib/baza-rb.rb

@@ -476,6 +476,7 @@ def transfer(recipient, amount, summary, job: nil, badge: nil)
   # @raise [ServerFailure] If the payment fails
   def fee(tab, amount, summary, job)
     raise(RuntimeError, 'The "tab" is nil') if tab.nil?
+    raise(RuntimeError, 'The "tab" may not be empty') if tab.empty?
     raise(RuntimeError, 'The "amount" is nil') if amount.nil?
     unless amount.is_a?(Float) || amount.is_a?(BigDecimal)
       raise(RuntimeError, 'The "amount" must be Float or BigDecimal')

lib/baza-rb/fake.rb

@@ -224,6 +224,7 @@ def transfer(recipient, amount, summary, job: nil, badge: nil)
   # @return [Integer] Always returns 42 as the fake receipt ID
   def fee(tab, amount, summary, job)
     raise(RuntimeError, 'The "tab" is nil') if tab.nil?
+    raise(RuntimeError, 'The "tab" may not be empty') if tab.empty?
     raise(RuntimeError, 'The "amount" is nil') if amount.nil?
     unless amount.is_a?(Float) || amount.is_a?(BigDecimal)
       raise(RuntimeError, 'The "amount" must be Float or BigDecimal')

test/test_baza_edge.rb

@@ -813,6 +813,13 @@ def test_fee_raises_when_amount_is_not_positive
     end
   end
 
+  def test_fee_raises_when_tab_is_empty
+    assert_equal(
+      'The "tab" may not be empty',
+      assert_raises(RuntimeError) { fake_baza.fee('', 1.0, 'pay', 42) }.message
+    )
+  end
+
   def test_fee_raises_when_summary_is_empty
     assert_equal(
       'The summary "" is empty',

test/test_fake.rb

@@ -297,6 +297,13 @@ def test_fee_raises_when_amount_is_not_positive
     )
   end
 
+  def test_fee_raises_when_tab_is_empty
+    assert_equal(
+      'The "tab" may not be empty',
+      assert_raises(RuntimeError) { BazaRb::Fake.new.fee('', 1.0, 'for fun', 44) }.message
+    )
+  end
+
   def test_fee_raises_when_job_is_not_positive
     assert_equal(
       'The "job" must be positive',