add mock airmass mode

firmware/controllers/algo/auto_generated_enums.cpp

@@ -735,6 +735,8 @@ case LM_SPEED_DENSITY:
   return "LM_SPEED_DENSITY";
 case LM_ALPHA_N_2:
   return "LM_ALPHA_N_2";
+case LM_MOCK:
+  return "LM_MOCK";
   }
  return NULL;
 }

firmware/controllers/algo/engine.h

@@ -16,6 +16,7 @@
 #include "accel_enrichment.h"
 #include "trigger_central.h"
 #include "local_version_holder.h"
+#include "airmass.h"
 
 #if EFI_SIGNAL_EXECUTOR_ONE_TIMER
 // PROD real firmware uses this implementation
@@ -334,6 +335,10 @@ public:
 	void knockLogic(float knockVolts DECLARE_ENGINE_PARAMETER_SUFFIX);
 	void printKnockState(void);
 
+#if EFI_UNIT_TEST
+	AirmassModelBase* mockAirmassModel = nullptr;
+#endif
+
 private:
 	/**
 	 * By the way:

firmware/controllers/algo/fuel_math.cpp

@@ -179,6 +179,9 @@ AirmassModelBase* getAirmassModel(DECLARE_ENGINE_PARAMETER_SIGNATURE) {
 		case LM_SPEED_DENSITY: return &sdAirmass;
 		case LM_REAL_MAF: return &mafAirmass;
 		case LM_ALPHA_N_2: return &alphaNAirmass;
+#if EFI_UNIT_TEST
+		case LM_MOCK: return engine->mockAirmassModel;
+#endif
 		default: return nullptr;
 	}
 }

firmware/controllers/algo/rusefi_enums.h

@@ -446,6 +446,9 @@ typedef enum {
 	// todo: rename after LM_ALPHA_N is removed
 	LM_ALPHA_N_2 = 5,
 
+	// This mode is for unit testing only, so that tests don't have to rely on a particular real airmass mode
+	LM_MOCK = 100,
+
 	Force_4_bytes_size_engine_load_mode = ENUM_32_BITS,
 } engine_load_mode_e;