diff --git a/cc/config/bp2build_test.go b/cc/config/bp2build_test.go
new file mode 100644
index 0000000..7744b4b
--- /dev/null
+++ b/cc/config/bp2build_test.go
@@ -0,0 +1,91 @@
+// Copyright 2021 Google Inc. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package config
+
+import (
+	"testing"
+)
+
+func TestExpandVars(t *testing.T) {
+	testCases := []struct {
+		description    string
+		exportedVars   map[string]variableValue
+		toExpand       string
+		expectedValues []string
+	}{
+		{
+			description: "single level expansion",
+			exportedVars: map[string]variableValue{
+				"foo": variableValue([]string{"bar"}),
+			},
+			toExpand:       "${foo}",
+			expectedValues: []string{"bar"},
+		},
+		{
+			description: "double level expansion",
+			exportedVars: map[string]variableValue{
+				"foo": variableValue([]string{"${bar}"}),
+				"bar": variableValue([]string{"baz"}),
+			},
+			toExpand:       "${foo}",
+			expectedValues: []string{"baz"},
+		},
+		{
+			description: "double level expansion with a literal",
+			exportedVars: map[string]variableValue{
+				"a": variableValue([]string{"${b}", "c"}),
+				"b": variableValue([]string{"d"}),
+			},
+			toExpand:       "${a}",
+			expectedValues: []string{"d", "c"},
+		},
+		{
+			description: "double level expansion, with two variables in a string",
+			exportedVars: map[string]variableValue{
+				"a": variableValue([]string{"${b} ${c}"}),
+				"b": variableValue([]string{"d"}),
+				"c": variableValue([]string{"e"}),
+			},
+			toExpand:       "${a}",
+			expectedValues: []string{"d", "e"},
+		},
+		{
+			description: "triple level expansion with two variables in a string",
+			exportedVars: map[string]variableValue{
+				"a": variableValue([]string{"${b} ${c}"}),
+				"b": variableValue([]string{"${c}", "${d}"}),
+				"c": variableValue([]string{"${d}"}),
+				"d": variableValue([]string{"foo"}),
+			},
+			toExpand:       "${a}",
+			expectedValues: []string{"foo", "foo", "foo"},
+		},
+	}
+
+	for _, testCase := range testCases {
+		t.Run(testCase.description, func(t *testing.T) {
+			output := expandVar(testCase.toExpand, testCase.exportedVars)
+			if len(output) != len(testCase.expectedValues) {
+				t.Errorf("Expected %d values, got %d", len(testCase.expectedValues), len(output))
+			}
+			for i, actual := range output {
+				expectedValue := testCase.expectedValues[i]
+				if actual != expectedValue {
+					t.Errorf("Actual value '%s' doesn't match expected value '%s'", actual, expectedValue)
+				}
+			}
+		})
+	}
+}