diff --git a/test/test_debugger.py b/test/test_debugger.py
index a884aa1..dfbbf9d 100644
--- a/test/test_debugger.py
+++ b/test/test_debugger.py
@@ -18,6 +18,7 @@ def debugger():
 SET(R1, 10)
 SET(R2, 32)
 ADD(R3, R1, R2)
+HALT()
 """
 )
 _symtab = get_symtab(_tree)
@@ -25,6 +26,15 @@ def debugger():
 
 
 def test_print_breakpoints(debugger, capsys):
+    debugger.breakpoints[4] = "main.hera:7"
+
+    should_continue = debugger.handle_command("break")
+
+    assert should_continue
+    assert capsys.readouterr().out == "main.hera:7\n"
+
+
+def test_print_breakpoints_with_no_breakpoints_set(debugger, capsys):
     should_continue = debugger.handle_command("break")
 
     assert should_continue
@@ -90,6 +100,35 @@ def test_execute_next(debugger):
     assert debugger.vm.pc == 2
 
 
+def test_execute_next_with_halt(debugger, capsys):
+    # Last instruction of SAMPLE_PROGRAM is a HALT operation.
+    debugger.vm.pc = len(debugger.program) - 1
+
+    should_continue = debugger.handle_command("next")
+
+    assert should_continue
+    assert debugger.vm.pc == len(debugger.program) - 1
+    assert capsys.readouterr().out == "Program has finished executing.\n"
+
+
+def test_execute_next_after_end_of_program(debugger, capsys):
+    debugger.vm.pc = 9000
+
+    should_continue = debugger.handle_command("next")
+
+    assert should_continue
+    assert debugger.vm.pc == 9000
+    assert capsys.readouterr().out == "Program has finished executing. Press 'r' to restart.\n"
+
+
+def test_execute_next_with_too_many_args(debugger, capsys):
+    # TODO: It would actually be useful if this worked.
+    should_continue = debugger.handle_command("next 10")
+
+    assert should_continue
+    assert capsys.readouterr().out == "next takes no arguments.\n"
+
+
 def test_execute_abbreviated_next(debugger):
     with patch("hera.debugger.Debugger.exec_next") as mock_exec_next:
         debugger.handle_command("n")
@@ -108,7 +147,7 @@ def test_execute_continue_with_breakpoint(debugger):
     assert debugger.vm.pc == 4
 
 
-def test_execute_continue_without_breakpoint(debugger):
+def test_execute_continue_without_breakpoint(debugger, capsys):
     should_continue = debugger.handle_command("continue")
 
     assert should_continue
@@ -116,6 +155,14 @@ def test_execute_continue_without_breakpoint(debugger):
     assert debugger.vm.registers[2] == 32
     assert debugger.vm.registers[3] == 42
     assert debugger.vm.pc == 5
+    assert capsys.readouterr().out == "Program has finished executing.\n"
+
+
+def test_execute_continue_with_too_many_args(debugger, capsys):
+    should_continue = debugger.handle_command("continue 10")
+
+    assert should_continue
+    assert capsys.readouterr().out == "continue takes no arguments.\n"
 
 
 def test_execute_abbreviated_continue(debugger):
@@ -158,11 +205,41 @@ def test_print_memory_location(debugger, capsys):
     assert capsys.readouterr().out == "M[97] = 1000\n"
 
 
+def test_execute_print_with_too_few_args(debugger, capsys):
+    # TODO: It would be useful if this printed the last printed expression again.
+    should_continue = debugger.handle_command("print")
+
+    assert should_continue
+    assert capsys.readouterr().out == "print takes one argument.\n"
+
+
+def test_execute_abbreviated_print(debugger):
+    with patch("hera.debugger.Debugger.exec_print") as mock_exec_print:
+        debugger.handle_command("p r7")
+        assert mock_exec_print.call_count == 1
+
+        args = mock_exec_print.call_args[0]
+        assert len(args) == 1
+        assert args[0] == ["r7"]
+
+        kwargs = mock_exec_print.call_args[1]
+        assert len(kwargs) == 0
+
+
 def test_execute_quit(debugger):
     assert debugger.handle_command("quit") is False
     assert debugger.handle_command("q") is False
 
 
+def test_execute_help(debugger, capsys):
+    should_continue = debugger.handle_command("help")
+
+    assert should_continue
+    out = capsys.readouterr().out
+    assert "Available commands" in out
+    assert "Error:" not in out
+
+
 def test_execute_unknown_command(debugger, capsys):
     should_continue = debugger.handle_command("whatever")