Add error messages and unit tests for setups where min_budget >= max_budget

src/dehb/optimizers/dehb.py

@@ -27,6 +27,18 @@ def __init__(self, cs=None, f=None, dimensions=None, mutation_factor=None,
                  crossover_prob=None, strategy=None, min_budget=None,
                  max_budget=None, eta=None, min_clip=None, max_clip=None,
                  boundary_fix_type='random', max_age=np.inf, **kwargs):
+        # Miscellaneous
+        self.output_path = kwargs['output_path'] if 'output_path' in kwargs else './'
+        os.makedirs(self.output_path, exist_ok=True)
+        self.logger = logger
+        log_suffix = time.strftime("%x %X %Z")
+        log_suffix = log_suffix.replace("/", '-').replace(":", '-').replace(" ", '_')
+        self.logger.add(
+            "{}/dehb_{}.log".format(self.output_path, log_suffix),
+            **_logger_props
+        )
+        self.log_filename = "{}/dehb_{}.log".format(self.output_path, log_suffix)
+
         # Benchmark related variables
         self.cs = cs
         self.configspace = True if isinstance(self.cs, ConfigSpace.ConfigurationSpace) else False
@@ -59,7 +71,19 @@ def __init__(self, cs=None, f=None, dimensions=None, mutation_factor=None,
         # Hyperband related variables
         self.min_budget = min_budget
         self.max_budget = max_budget
-        assert self.max_budget > self.min_budget, "only (Max Budget > Min Budget) supported!"
+        if self.max_budget <= self.min_budget:
+            self.logger.error("Only (Max Budget > Min Budget) is supported for DEHB.")
+            if self.max_budget == self.min_budget:
+                self.logger.error(
+                    "If you have a fixed fidelity, " \
+                    "you can instead run DE as follows: " \
+                    "AsyncDE(cs=configspace, f=target_function, dimensions=" \
+                    f"{self.dimensions}, pop_size={self.dimensions * 2}, " \
+                    f"max_age={self.max_age}, mutation_factor=" \
+                    f"{self.mutation_factor}, crossover_prob={self.crossover_prob}, "\
+                    f"strategy={self.strategy}, budget={self.max_budget}, " \
+                    f"boundary_fix_type={self.fix_type})")
+            sys.exit()
         self.eta = eta
         self.min_clip = min_clip
         self.max_clip = max_clip
@@ -75,17 +99,6 @@ def __init__(self, cs=None, f=None, dimensions=None, mutation_factor=None,
                                                      -np.linspace(start=self.max_SH_iter - 1,
                                                                   stop=0, num=self.max_SH_iter))
 
-        # Miscellaneous
-        self.output_path = kwargs['output_path'] if 'output_path' in kwargs else './'
-        os.makedirs(self.output_path, exist_ok=True)
-        self.logger = logger
-        log_suffix = time.strftime("%x %X %Z")
-        log_suffix = log_suffix.replace("/", '-').replace(":", '-').replace(" ", '_')
-        self.logger.add(
-            "{}/dehb_{}.log".format(self.output_path, log_suffix),
-            **_logger_props
-        )
-        self.log_filename = "{}/dehb_{}.log".format(self.output_path, log_suffix)
         # Updating DE parameter list
         self.de_params.update({"output_path": self.output_path})
 

tests/test_dehb.py

@@ -1,10 +1,12 @@
-import pytest
+import time
 import typing
+
 import ConfigSpace
 import numpy as np
-import time
+import pytest
 from src.dehb.optimizers.dehb import DEHB
 
+
 def create_toy_searchspace():
     """Creates a toy searchspace with a single hyperparameter.
 
@@ -66,8 +68,7 @@ class TestBudgetExhaustion():
     evaluations and number of brackets to run.
     """
     def test_runtime_exhaustion(self):
-        """Test for runtime budget exhaustion.
-        """
+        """Test for runtime budget exhaustion."""
         cs = create_toy_searchspace()
         dehb = create_toy_optimizer(configspace=cs, min_budget=3, max_budget=27, eta=3,
                                         objective_function=objective_function)
@@ -77,8 +78,7 @@ def test_runtime_exhaustion(self):
         assert dehb._is_run_budget_exhausted(total_cost=1), "Run budget should be exhausted"
 
     def test_fevals_exhaustion(self):
-        """Test for function evaluations budget exhaustion.
-        """
+        """Test for function evaluations budget exhaustion."""
         cs = create_toy_searchspace()
         dehb = create_toy_optimizer(configspace=cs, min_budget=3, max_budget=27, eta=3,
                                     objective_function=objective_function)
@@ -88,8 +88,7 @@ def test_fevals_exhaustion(self):
         assert dehb._is_run_budget_exhausted(fevals=1), "Run budget should be exhausted"
 
     def test_brackets_exhaustion(self):
-        """Test for bracket budget exhaustion.
-        """
+        """Test for bracket budget exhaustion."""
         cs = create_toy_searchspace()
         dehb = create_toy_optimizer(configspace=cs, min_budget=3, max_budget=27, eta=3,
                                         objective_function=objective_function)
@@ -98,3 +97,11 @@ def test_brackets_exhaustion(self):
 
         assert dehb._is_run_budget_exhausted(brackets=1), "Run budget should be exhausted"
 
+class TestInitialization:
+    """Class that bundles all tests regarding the initialization of DEHB."""
+    def test_higher_min_budget(self):
+        """Test that verifies, that DEHB breaks if min_budget > max_budget."""
+        cs = create_toy_searchspace()
+        with pytest.raises(SystemExit):
+            create_toy_optimizer(configspace=cs, min_budget=28, max_budget=27, eta=3,
+                                        objective_function=objective_function)