feat: add evse_charging_enabled() helper with tests for EVCC integration

Extract the charging_enabled derivation into a testable pure C function
in http_api.c. Add 3 tests covering STATE_C, STATE_C1, and all
non-charging states.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: basmeerman

SmartEVSE-3/src/http_api.c

@@ -53,6 +53,10 @@ char evse_state_to_iec61851(int state, int error_flags) {
     }
 }
 
+bool evse_charging_enabled(int state) {
+    return (state == STATE_C || state == STATE_C1);
+}
+
 const char *http_api_validate_phase_switch(const http_phase_switch_request_t *req,
                                            int enable_c2, int load_bl) {
     if (req->phases != 1 && req->phases != 3)

SmartEVSE-3/src/http_api.h

@@ -104,6 +104,10 @@ const char *http_api_validate_phase_switch(const http_phase_switch_request_t *re
 // NOSTATE or unrecognized values return 'F' (not available).
 char evse_state_to_iec61851(int state, int error_flags);
 
+// Derive whether charging is actively enabled from internal state.
+// Returns true when the EVSE is delivering energy (STATE_C or STATE_C1).
+bool evse_charging_enabled(int state);
+
 #ifdef __cplusplus
 }
 #endif

SmartEVSE-3/src/http_handlers.cpp

@@ -170,7 +170,7 @@ bool handle_URI(struct mg_connection *c, struct mg_http_message *hm,  webServerR
         doc["evse"]["rfid"] = !RFIDReader ? "Not Installed" : RFIDstatus >= 8 ? "NOSTATUS" : StrRFIDStatusWeb[RFIDstatus];
         char iec_buf[2] = {evse_state_to_iec61851(State, ErrorFlags), '\0'};
         doc["evse"]["iec61851_state"] = iec_buf;
-        doc["evse"]["charging_enabled"] = (State == STATE_C || State == STATE_C1);
+        doc["evse"]["charging_enabled"] = evse_charging_enabled(State);
         if (RFIDReader) {
             char buf[15];
             printRFID(buf, sizeof(buf));

SmartEVSE-3/test/native/tests/test_http_api.c

@@ -787,6 +787,52 @@ void test_iec61851_nostate_and_unknown(void) {
     TEST_ASSERT_EQUAL_INT('F', evse_state_to_iec61851(99, NO_ERROR));
 }
 
+// ---- Charging Enabled Derivation ----
+
+/*
+ * @feature EVCC Charging Enabled
+ * @req REQ-API-025
+ * @scenario STATE_C means charging is enabled
+ * @given The EVSE is in STATE_C (charging)
+ * @when evse_charging_enabled is called
+ * @then It returns true
+ */
+void test_charging_enabled_state_c(void) {
+    TEST_ASSERT_TRUE(evse_charging_enabled(STATE_C));
+}
+
+/*
+ * @feature EVCC Charging Enabled
+ * @req REQ-API-025
+ * @scenario STATE_C1 means charging is enabled (stopping phase)
+ * @given The EVSE is in STATE_C1 (charge stopping)
+ * @when evse_charging_enabled is called
+ * @then It returns true because energy is still being delivered
+ */
+void test_charging_enabled_state_c1(void) {
+    TEST_ASSERT_TRUE(evse_charging_enabled(STATE_C1));
+}
+
+/*
+ * @feature EVCC Charging Enabled
+ * @req REQ-API-025
+ * @scenario Non-charging states return false
+ * @given The EVSE is in STATE_A, STATE_B, or other non-charging states
+ * @when evse_charging_enabled is called
+ * @then It returns false
+ */
+void test_charging_enabled_non_charging_states(void) {
+    TEST_ASSERT_FALSE(evse_charging_enabled(STATE_A));
+    TEST_ASSERT_FALSE(evse_charging_enabled(STATE_B));
+    TEST_ASSERT_FALSE(evse_charging_enabled(STATE_B1));
+    TEST_ASSERT_FALSE(evse_charging_enabled(STATE_D));
+    TEST_ASSERT_FALSE(evse_charging_enabled(STATE_COMM_B));
+    TEST_ASSERT_FALSE(evse_charging_enabled(STATE_ACTSTART));
+    TEST_ASSERT_FALSE(evse_charging_enabled(STATE_MODEM_REQUEST));
+    TEST_ASSERT_FALSE(evse_charging_enabled(STATE_MODEM_DENIED));
+    TEST_ASSERT_FALSE(evse_charging_enabled(NOSTATE));
+}
+
 // ---- Phase Switch Validation ----
 
 /*
@@ -976,6 +1022,11 @@ int main(void) {
     RUN_TEST(test_iec61851_soft_errors_no_override);
     RUN_TEST(test_iec61851_nostate_and_unknown);
 
+    // Charging enabled derivation
+    RUN_TEST(test_charging_enabled_state_c);
+    RUN_TEST(test_charging_enabled_state_c1);
+    RUN_TEST(test_charging_enabled_non_charging_states);
+
     // Phase switch validation
     RUN_TEST(test_phase_switch_valid_1p);
     RUN_TEST(test_phase_switch_valid_3p);