Squashed commit of the following:

commit e5a5749971eb9274679699020a54c91d4053ed79
Author: James Fraser <wulfgar.pro@gmail.com>
Date:   Sun Feb 3 19:57:31 2019 +1100

    PR #47: Minor review fixes to tests files.

commit e9f11b9ec8de8f8d1f0de7b6959c575e15894526
Author: James Fraser <wulfgar.pro@gmail.com>
Date:   Sun Feb 3 19:57:04 2019 +1100

    PR #47: Minor review fixes.

commit 0a7fbeceec
Author: Pauli Salmenrinne <pauli.salmenrinne@pexraytech.com>
Date:   Tue Jan 22 15:11:10 2019 +0200

    Add example for the weak linking

commit 647737304d
Author: susundberg <susundberg@gmail.com>
Date:   Wed Mar 21 13:14:05 2018 +0200

    Add "FFF_FUNCTION_ATTRIBUTES" definition that can be used to declare attributes for functions. More specifically, allow __weak__ attribute.

README.md

@@ -21,6 +21,7 @@
 - [How do I fake a function that returns a value by reference?](#how-do-i-fake-a-function-that-returns-a-value-by-reference)
 - [How do I fake a function with a function pointer parameter?](#how-do-i-fake-a-function-with-a-function-pointer-parameter)
 - [How do I reuse a fake across multiple test-suites?](#how-do-i-reuse-a-fake-across-multiple-test-suites)
+- [Specifying GCC Function Attributes](#specifying-gcc-function-attributes)
 - [Find out more...](#find-out-more)
 - [Benefits](#benefits)
 - [Under the hood](#under-the-hood)
@@ -603,6 +604,26 @@ DEFINE_FAKE_VALUE_FUNC_VARARG(int, value_function_vargs, const char *, int, ...)
 DEFINE_FAKE_VOID_FUNC_VARARG(void_function_vargs, const char *, int, ...);
 
 ```
+## Specifying GCC Function Attributes
+
+You can specify GCC function attributes for your fakes using the `FFF_GCC_FUNCTION_ATTRIBUTES` directive.
+
+### Weak Functions
+
+One usful attribute is the _weak_ attribute that marks a function such that it can be overridden by a non-weak variant at link time.  Using weak functions in combination with FFF can help simplify your testing approach.
+
+For example:
+* Define a library of fake functions, e.g. libfake.a.
+* Link a binary (you might have many) that defines a subset of real variants of the fake functions to the aforementioned fake library.
+* This has the benefit of allowing a binary to selectively use a subset of the required fake functions while testing the real variants without the need for many different make targets.
+
+You can mark all fakes with the weak attribute like so:
+```
+#define FFF_GCC_FUNCTION_ATTRIBUTES __attribute__((weak))
+#include "fff.h"
+```
+
+See the example project that demonstrates the above approach: _./examples/weak_linking_.
 
 ## Find out more...
 
@@ -621,8 +642,9 @@ So whats the point?
 
 ## Under the Hood
  * The fff.h header file is generated by a ruby script
- * There are tests under src/test
- * There is an example for testing an embedded UI and a hardware driver under src/examples
+ * There are tests under _./test_
+ * There is an example for testing an embedded UI and a hardware driver under _./examples_
+ * There is an example of weak_linking under _./examples_
 
 
 ## Cheat Sheet

buildandtest

@@ -14,3 +14,7 @@ build/fff_test_glob_c
 build/fff_test_glob_cpp --gtest_output=xml:build/test_global_results.xml
 build/driver_testing --gtest_output=xml:build/driver_testing.xml
 build/driver_testing_fff  --gtest_output=xml:build/driver_testing_fff.xml
+build/weak_linking/test_display
+build/weak_linking/test_sensor
+build/weak_linking/test_main
+

examples/Makefile

@@ -1,7 +1,9 @@
 all: 
 	cd embedded_ui; $(MAKE) all
 	cd driver_testing; $(MAKE) all
-
+	cd weak_linking; $(MAKE) all
 clean: 
 	cd embedded_ui; $(MAKE) clean
 	cd driver_testing; $(MAKE) clean
+	cd weak_linking; $(MAKE) clean
+

examples/weak_linking/Makefile

@@ -0,0 +1,39 @@
+BUILD_DIR = ../../build
+INCLUDE_DIRS = -I "../../" -I "./src/"
+
+BUILD_DIR_FAKE =  $(BUILD_DIR)/weak_linking
+CC = gcc
+WEAK_FLAGS=-Wall -DFFF_GCC_FUNCTION_ATTRIBUTES="__attribute__((weak))"
+
+$(BUILD_DIR_FAKE)/%.o: test/%.c
+	@echo "Compiling "$@
+	$(CC) $(WEAK_FLAGS) $(INCLUDE_DIRS) -g -O0 -c $< -o $@
+
+FAKE_OBJECTS = $(BUILD_DIR_FAKE)/display.fake.o $(BUILD_DIR_FAKE)/sensor.fake.o $(BUILD_DIR_FAKE)/sensor.fake.o $(BUILD_DIR_FAKE)/error.fake.o  $(BUILD_DIR_FAKE)/bus.fake.o $(BUILD_DIR_FAKE)/test_common.o
+
+TEST_BINARIES = $(BUILD_DIR_FAKE)/test_main $(BUILD_DIR_FAKE)/test_display $(BUILD_DIR_FAKE)/test_sensor
+mkdir:
+	mkdir -p $(BUILD_DIR_FAKE)/
+
+clean:
+	rm -rf $(BUILD_DIR_FAKE)/
+
+$(BUILD_DIR_FAKE)/libfakes.a:  $(FAKE_OBJECTS)
+	ar r $@  $^
+
+# First case where we need __weak__ linking:
+#  - If we have the build objects (for some reason) in order where the fake object comes first.
+$(BUILD_DIR_FAKE)/test_display: ./test/display.test.c $(BUILD_DIR_FAKE)/libfakes.a ./src/display.c
+	$(CC) $(WEAK_FLAGS) $(INCLUDE_DIRS) -o $@ $^
+
+# Second case where we need weak linking:
+#  - If we use an object from the fake object -> gcc linker will include it.
+$(BUILD_DIR_FAKE)/test_sensor: ./test/sensor.test.c ./src/sensor.c $(BUILD_DIR_FAKE)/libfakes.a
+	$(CC) $(WEAK_FLAGS) $(INCLUDE_DIRS) -o $@ $^
+
+# Third case where we need weak linking:
+#  - We want to fake one function but not all.
+$(BUILD_DIR_FAKE)/test_main: ./test/main.test.c ./src/main.c $(BUILD_DIR_FAKE)/libfakes.a
+	$(CC) $(WEAK_FLAGS) $(INCLUDE_DIRS) -o $@ $^
+
+all: mkdir $(TEST_BINARIES)

examples/weak_linking/src/bus.c

@@ -0,0 +1,30 @@
+#pragma once
+
+uint16_t* BUS_REGISTER_BASE = (uint16_t*)0xDEADBEEF;
+
+typedef struct
+{
+    uint16_t action;
+    uint16_t reg;
+    uint8_t  input;
+    uint8_t  output
+} BusDevice;
+
+BusDevice* BUS = (BusDevice*)BUS_REGISTER_BASE;
+
+bool bus_read_write( uint8_t dev, uint8_t registry, uint8_t* buffer, int len, bool assume_echo )
+{
+    // Something that we dont want to run, since the emulation would be hard.
+    BUS->action = 0x01;
+    BUS->reg = registry;
+    for ( int loop =0 ; loop < len; loop ++ )
+    {
+        char output = buffer[loop];
+        BUS->output  = output;
+        buffer[loop] = BUS->input;
+
+        if ( ( assume_echo ) && ( buffer[loop] != output ) )
+            return false;
+    }
+    return true;
+}

examples/weak_linking/src/bus.h

@@ -0,0 +1,6 @@
+#pragma once
+
+#include "error.h"
+
+bool bus_read_write( uint8_t dev, uint8_t registry, uint8_t* buffer, int len, bool assume_echo );
+bool bus_write( uint8_t dev, uint8_t registry, const uint8_t* buffer, int len, bool assume_echo );

examples/weak_linking/src/display.c

@@ -0,0 +1,29 @@
+#include <string.h>
+
+#include "display.h"
+#include "bus.h"
+
+#define DISPLAY_ADDRESS     0xAF
+#define DISPLAY_REG_INIT    0x10
+#define DISPLAY_REG_UPDATE  0x20
+
+bool display_init()
+{
+    char init_config[] = { 0xDE, 0xFE, 0x00 };
+    bus_read_write( DISPLAY_ADDRESS, DISPLAY_REG_INIT, (uint8_t*)init_config, 3, false );
+
+    if (init_config[2] != 0x10)
+        return false;
+
+    return true;
+}
+
+void display_update( const char* info )
+{
+    int len = strlen( info );
+
+    if ( bus_write( DISPLAY_ADDRESS, DISPLAY_REG_UPDATE, (const uint8_t*)info, len, true ) != true )
+    {
+        runtime_error("display update failed!");
+    }
+}

examples/weak_linking/src/display.h

@@ -0,0 +1,5 @@
+#pragma once
+#include "error.h"
+
+bool display_init();
+void display_update( const char* info );

examples/weak_linking/src/error.c

@@ -0,0 +1,10 @@
+#include <assert.h>
+#include "error.h"
+
+char* runtime_error_nice_print( const char* msg )
+{
+    char* buffer = malloc(512);
+    snprintf(buffer, 512, "Got error: %s", msg );
+    buffer[511] = 0;
+    return buffer;
+}

examples/weak_linking/src/error.h

@@ -0,0 +1,7 @@
+#pragma once
+
+#include <stdint.h>
+#include <stdbool.h>
+
+void runtime_error( const char* msg );
+char* runtime_error_nice_print( const char* msg );

examples/weak_linking/src/main.c

@@ -0,0 +1,27 @@
+#include <stdlib.h>
+#include <stdio.h>
+
+#include "display.h"
+#include "sensor.h"
+
+void give_error( const char* msg )
+{
+    char* buffer = runtime_error_nice_print( msg );
+    runtime_error( buffer );
+    free(buffer);
+}
+
+int update_main( void )
+{
+    if ( !sensor_init() )
+        runtime_error("sensor init failed");
+
+    if ( !display_init() )
+        runtime_error("display init failed");
+
+    char buffer[32];
+    float reading = sensor_read();
+    snprintf( buffer, 32, "Sensor: %0.1f", reading );
+    display_update( buffer );
+    return 0;
+}

examples/weak_linking/src/sensor.c

@@ -0,0 +1,29 @@
+#include <string.h>
+
+#include "sensor.h"
+#include "bus.h"
+
+#define SENSOR_ADDRESS 0xAA
+#define SENSOR_REG_READ 0xF0
+
+float LOCAL_buffer[4];
+
+bool sensor_init()
+{
+    memset( LOCAL_buffer, 0x00, sizeof(LOCAL_buffer));
+    return true;
+}
+
+float sensor_read()
+{
+    char data[4] = { 0xFF, 0xFF, 0x00, 0x00 };
+    bus_read_write( SENSOR_ADDRESS, SENSOR_REG_READ, (uint8_t*)&data, 4, false );
+
+    if (data[0] != 0x10)
+    {
+        runtime_error("sensor read failed");
+    }
+
+    float ret_value = data[1] + data[2] / 256.0;
+    return ret_value;
+}

examples/weak_linking/src/sensor.h

@@ -0,0 +1,6 @@
+#pragma once
+
+#include "error.h"
+
+bool sensor_init();
+float sensor_read();

examples/weak_linking/test/bus.fake.c

@@ -0,0 +1,4 @@
+#include "bus.fake.h"
+
+DEFINE_FAKE_VALUE_FUNC( bool, bus_read_write, uint8_t, uint8_t, uint8_t*, int, bool );
+DEFINE_FAKE_VALUE_FUNC( bool, bus_write, uint8_t, uint8_t, const uint8_t*, int, bool );

examples/weak_linking/test/bus.fake.h

@@ -0,0 +1,10 @@
+#ifndef _AUTOFAKE_BUS_H
+#define _AUTOFAKE_BUS_H
+
+#include "fff.h"
+#include "bus.h"
+
+DECLARE_FAKE_VALUE_FUNC( bool, bus_read_write, uint8_t, uint8_t, uint8_t*, int, bool );
+DECLARE_FAKE_VALUE_FUNC( bool, bus_write, uint8_t, uint8_t, const uint8_t*, int, bool );
+
+#endif  // _AUTOFAKE_BUS_H

examples/weak_linking/test/display.fake.c

@@ -0,0 +1,4 @@
+#include "display.fake.h"
+
+DEFINE_FAKE_VALUE_FUNC( bool, display_init );
+DEFINE_FAKE_VOID_FUNC( display_update, const char* );

examples/weak_linking/test/display.fake.h

@@ -0,0 +1,10 @@
+#ifndef _AUTOFAKE_DISPLAY_H
+#define _AUTOFAKE_DISPLAY_H
+
+#include "fff.h"
+#include "display.h"
+
+DECLARE_FAKE_VALUE_FUNC( bool, display_init );
+DECLARE_FAKE_VOID_FUNC( display_update, const char* );
+
+#endif  // _AUTOFAKE_DISPLAY_H

examples/weak_linking/test/display.test.c

@@ -0,0 +1,24 @@
+#include "test_common.h"
+#include "display.h"
+
+DEFINE_FFF_GLOBALS;
+
+
+int main(void)
+{
+   init_tests();  // Resets common and hook errors to asserts.
+
+   GLOBAL_TEST_bus_read_ret[2] = 0x10;
+   assert( display_init() == true );
+   assert( bus_read_write_fake.call_count == 1);
+
+   display_update( "TEST INFO" );
+   assert( bus_read_write_fake.call_count == 1 );
+   assert( bus_write_fake.call_count == 1 );
+
+   GLOBAL_TEST_bus_read_ret[2] = 0x00;
+   assert( display_init() == false );
+
+   printf("Test " __FILE__ " ok\n");
+   return 0;
+}

examples/weak_linking/test/error.fake.c

@@ -0,0 +1,4 @@
+#include "error.fake.h"
+
+DEFINE_FAKE_VOID_FUNC( runtime_error, const char* );
+DEFINE_FAKE_VALUE_FUNC( char*, runtime_error_nice_print, const char* );

examples/weak_linking/test/error.fake.h

@@ -0,0 +1,10 @@
+#ifndef _AUTOFAKE_ERROR_H
+#define _AUTOFAKE_ERROR_H
+
+#include "fff.h"
+#include "error.h"
+
+DECLARE_FAKE_VOID_FUNC( runtime_error, const char* );
+DECLARE_FAKE_VALUE_FUNC( char*, runtime_error_nice_print, const char* );
+
+#endif  // _AUTOFAKE_ERROR_H

examples/weak_linking/test/main.test.c

@@ -0,0 +1,26 @@
+
+#include "display.fake.h"
+#include "sensor.fake.h"
+#include "test_common.h"
+
+DEFINE_FFF_GLOBALS;
+
+
+int update_main( void );
+
+int main(void)
+{
+    init_tests();  // Resets common and hook errors to asserts.
+
+    sensor_init_fake.return_val = true;
+    display_init_fake.return_val = true;
+
+    update_main();
+
+    assert( sensor_init_fake.call_count == 1 );
+    assert( display_init_fake.call_count == 1 );
+    assert( display_update_fake.call_count == 1 );
+
+    printf("Test " __FILE__ " ok\n");
+    return 0;
+}

examples/weak_linking/test/sensor.fake.c

@@ -0,0 +1,11 @@
+#include "sensor.fake.h"
+
+DEFINE_FAKE_VALUE_FUNC( bool, sensor_init );
+DEFINE_FAKE_VALUE_FUNC( float, sensor_read );
+
+void TEST_sensor_generate_data( char* buffer, float value )
+{
+    buffer[0] = 0x10;
+    buffer[1] = (int)(value);
+    buffer[2] = (value - buffer[1])*255;
+}

examples/weak_linking/test/sensor.fake.h

@@ -0,0 +1,13 @@
+
+#ifndef _AUTOMOCK_SENSOR_H
+#define _AUTOMOCK_SENSOR_H
+
+#include "fff.h"
+#include "sensor.h"
+
+DECLARE_FAKE_VALUE_FUNC( bool, sensor_init );
+DECLARE_FAKE_VALUE_FUNC( float, sensor_read );
+
+void TEST_sensor_generate_data( char* buffer, float value );
+
+#endif // _AUTOMOCK_SENSOR_H

examples/weak_linking/test/sensor.test.c

@@ -0,0 +1,23 @@
+#include <stdio.h>
+
+#include "test_common.h"
+
+#include "sensor.h"
+#include "sensor.fake.h"
+
+DEFINE_FFF_GLOBALS;
+
+
+int main(void)
+{
+    init_tests();
+
+    assert( sensor_init() == true );
+
+    TEST_sensor_generate_data( GLOBAL_TEST_bus_read_ret, 1.5f );
+    float value = sensor_read();
+    float value_error = value - 1.5f;
+    assert( value_error < 0.1f && value_error > -0.1f );
+    printf("Test " __FILE__ " ok\n");
+    return 0;
+}

examples/weak_linking/test/test_common.c

@@ -0,0 +1,33 @@
+#include "test_common.h"
+#include <assert.h>
+#include <stdio.h>
+
+char GLOBAL_TEST_bus_read_ret[32];
+
+
+void spoof_runtime_error( const char* info )
+{
+    fprintf(stderr, "Runtime error: %s\n", info );
+    assert(0);
+}
+
+bool spoof_bus_read_write( uint8_t dev, uint8_t registry, uint8_t* buffer, int len, bool assume_echo )
+{
+    memcpy( buffer, GLOBAL_TEST_bus_read_ret, len );
+    fprintf(stderr, "bus spoof %d %d\n", (int)dev, (int)registry );
+    return true;
+}
+
+void init_tests()
+{
+    memset( GLOBAL_TEST_bus_read_ret, 0x00, sizeof(GLOBAL_TEST_bus_read_ret));
+    FFF_RESET_HISTORY();
+    
+    RESET_FAKE(bus_read_write);
+    RESET_FAKE(bus_write);
+    RESET_FAKE(runtime_error);
+    
+    runtime_error_fake.custom_fake = spoof_runtime_error;
+    bus_read_write_fake.custom_fake = spoof_bus_read_write;
+    bus_write_fake.return_val = true;
+}

examples/weak_linking/test/test_common.h

@@ -0,0 +1,13 @@
+#pragma once
+
+#include <assert.h>
+#include <stdio.h>
+
+#include "fff.h"
+#include "bus.fake.h"
+#include "error.fake.h"
+
+
+void init_tests();
+
+extern char GLOBAL_TEST_bus_read_ret[32];

fakegen.rb

@@ -26,6 +26,12 @@ def output_constants
     putd "#define FFF_CALL_HISTORY_LEN (#{$MAX_CALL_HISTORY}u)"
   }
   putd "#endif"
+  putd "#ifndef FFF_GCC_FUNCTION_ATTRIBUTES"
+  indent {
+     putd "#define FFF_GCC_FUNCTION_ATTRIBUTES"
+  }
+  putd "#endif"
+  
 end
 
 
@@ -384,8 +390,8 @@ def function_signature(arg_count, has_varargs, has_calling_conventions, is_value
   return_type = is_value_function ? "RETURN_TYPE" : "void"
   varargs = has_varargs ? ", ..." : ""
   calling_conventions = has_calling_conventions ?
-    "#{return_type} CALLING_CONVENTION FUNCNAME(#{arg_val_list(arg_count)}#{varargs})" :
-    "#{return_type} FUNCNAME(#{arg_val_list(arg_count)}#{varargs})"
+    "#{return_type} FFF_GCC_FUNCTION_ATTRIBUTES CALLING_CONVENTION FUNCNAME(#{arg_val_list(arg_count)}#{varargs})" :
+    "#{return_type} FFF_GCC_FUNCTION_ATTRIBUTES FUNCNAME(#{arg_val_list(arg_count)}#{varargs})"
 end
 
 def output_function_body(arg_count, has_varargs, is_value_function)