test(bf-4lid): add comprehensive test environment config helper tests

- Add GetTestMaxRetries_WithOverride test to verify MAX_RETRIES env var handling
- Add ConfigureTestEnv test to verify all required environment variables are set
- Test coverage includes: valid/invalid env values, all 7 required vars
- All acceptance criteria for bead bf-4lid are now verified

notes/bf-4lid.md

@@ -0,0 +1,50 @@
+# Test Environment Configuration Helper Verification
+
+## Summary
+
+Verified and completed test coverage for test environment configuration helper functions in `proxy/helpers_test.go`.
+
+## Changes Made
+
+### Added Test Cases to `TestHelperFunctions`
+
+1. **`GetTestMaxRetries_WithOverride`** - Tests that `GetTestMaxRetries()` correctly respects the `MAX_RETRIES` environment variable:
+   - Valid values: 0, 1, 5, 100 are properly parsed and returned
+   - Invalid values: "abc" (text), "-1" (negative) fall back to `DefaultTestMaxRetries` (1)
+
+2. **`ConfigureTestEnv`** - Tests that `ConfigureTestEnv()` sets all required environment variables:
+   - `MAX_RETRIES` = "1" (DefaultTestMaxRetries)
+   - `ZAI_PROXY_TEST_MODE` = "true"
+   - `DEPLOYMENT_VARIANT` = "test"
+   - `TOKEN_COUNTING_ENABLED` = "false"
+   - `RATE_LIMIT_INITIAL` = "1000"
+   - `RATE_LIMIT_MIN` = "1000"
+   - `RATE_LIMIT_MAX` = "1000"
+
+## Test Results
+
+All tests pass successfully:
+```
+=== RUN   TestHelperFunctions/GetTestMaxRetries_WithOverride
+    --- PASS: TestHelperFunctions/GetTestMaxRetries_WithOverride/zero (0.00s)
+    --- PASS: TestHelperFunctions/GetTestMaxRetries_WithOverride/one (0.00s)
+    --- PASS: TestHelperFunctions/GetTestMaxRetries_WithOverride/five (0.00s)
+    --- PASS: TestHelperFunctions/GetTestMaxRetries_WithOverride/large (0.00s)
+    --- PASS: TestHelperFunctions/GetTestMaxRetries_WithOverride/invalid_text (0.00s)
+    --- PASS: TestHelperFunctions/GetTestMaxRetries_WithOverride/negative (0.00s)
+=== RUN   TestHelperFunctions/ConfigureTestEnv
+    --- PASS: TestHelperFunctions/ConfigureTestEnv/RATE_LIMIT_MAX (0.00s)
+    --- PASS: TestHelperFunctions/ConfigureTestEnv/MAX_RETRIES (0.00s)
+    --- PASS: TestHelperFunctions/ConfigureTestEnv/ZAI_PROXY_TEST_MODE (0.00s)
+    --- PASS: TestHelperFunctions/ConfigureTestEnv/DEPLOYMENT_VARIANT (0.00s)
+    --- PASS: TestHelperFunctions/ConfigureTestEnv/TOKEN_COUNTING_ENABLED (0.00s)
+    --- PASS: TestHelperFunctions/ConfigureTestEnv/RATE_LIMIT_INITIAL (0.00s)
+    --- PASS: TestHelperFunctions/ConfigureTestEnv/RATE_LIMIT_MIN (0.00s)
+```
+
+## Acceptance Criteria Verification
+
+1. ✅ `IsTestMode()` correctly detects test mode during test execution (already covered)
+2. ✅ `GetTestMaxRetries()` returns `DefaultTestMaxRetries` (1) by default (already covered)
+3. ✅ `GetTestMaxRetries()` respects `MAX_RETRIES` environment variable override (newly added)
+4. ✅ `ConfigureTestEnv()` sets all required environment variables (newly added)

proxy/helpers_test.go

@@ -605,6 +605,58 @@ func TestHelperFunctions(t *testing.T) {
 		}
 	})
 
+	t.Run("GetTestMaxRetries_WithOverride", func(t *testing.T) {
+		// Test that GetTestMaxRetries respects MAX_RETRIES environment variable
+		testCases := []struct {
+			name          string
+			envValue      string
+			expected      int
+			shouldDefault bool
+		}{
+			{"zero", "0", 0, false},
+			{"one", "1", 1, false},
+			{"five", "5", 5, false},
+			{"large", "100", 100, false},
+			{"invalid_text", "abc", 1, true}, // Should default to DefaultTestMaxRetries
+			{"negative", "-1", 1, true},      // Should default to DefaultTestMaxRetries
+		}
+
+		for _, tc := range testCases {
+			t.Run(tc.name, func(t *testing.T) {
+				t.Setenv(TestMaxRetriesEnv, tc.envValue)
+				result := GetTestMaxRetries()
+				if result != tc.expected {
+					t.Errorf("Expected %d, got %d", tc.expected, result)
+				}
+			})
+		}
+	})
+
+	t.Run("ConfigureTestEnv", func(t *testing.T) {
+		// Test that ConfigureTestEnv sets all required environment variables
+		ConfigureTestEnv(t)
+
+		// Verify all required environment variables are set
+		expectedVars := map[string]string{
+			TestMaxRetriesEnv:    strconv.Itoa(DefaultTestMaxRetries),
+			TestModeEnv:          "true",
+			"DEPLOYMENT_VARIANT": "test",
+			"TOKEN_COUNTING_ENABLED": "false",
+			"RATE_LIMIT_INITIAL": "1000",
+			"RATE_LIMIT_MIN": "1000",
+			"RATE_LIMIT_MAX": "1000",
+		}
+
+		for key, expectedValue := range expectedVars {
+			t.Run(key, func(t *testing.T) {
+				actualValue := os.Getenv(key)
+				if actualValue != expectedValue {
+					t.Errorf("Environment variable %s: expected %q, got %q", key, expectedValue, actualValue)
+				}
+			})
+		}
+	})
+
 	t.Run("CalculateBackoffDelay", func(t *testing.T) {
 		testCases := []struct {
 			attempt   int