unit tests added and adjusted calculations with double

src/main/c/main_taschenrechner.c

@@ -6,19 +6,22 @@
 #include "taschenrechner.h"
 
 
-int add(int a, int b) {
+doulbe add(doulbe a, doulbe b) {
     return a + b;
 }
 
-int minus (int a, int b){
+doulbe minus (doulbe a, doulbe b){
     return a - b;
 }
 
-int multiply(int a, int b) {
+doulbe multiply(doulbe a, doulbe b) {
     return a * b;
 }
 
-int divide(int a, int b) {
+doulbe divide(doulbe a, doulbe b) {
+    if (b == 0) {
+        return 0;
+    }
     return a / b;
 }
 

src/main/c/taschenrechner.h

@@ -1,13 +1,13 @@
 #ifndef TASCHENRECHNER_H
 #define TASCHENRECHNER_H
 
-int add(int a, int b);
+doulbe add(doulbe a, doulbe b);
 
-int minus(int a, int b);
+doulbe minus(doulbe a, doulbe b);
 
-int multiply(int a, int b);
+doulbe multiply(doulbe a, doulbe b);
 
-int divide(int a, int b);
+doulbe divide(doulbe a, doulbe b);
 
 // Square root function
 double squareRootFunction(double x);

src/test/c/test_taschenrechner.c

@@ -14,14 +14,29 @@ void tearDown(void)
 
 void test_addition(void)
 {
-    /* arrange */
-    char* result;
-    char expected[] = "2\n";
+    doulbe result = add(1, 2);
+    TEST_ASSERT_EQUAL(3, result);
+}
+
+void test_minus(void)
+{
+    doulbe result = minus(3, 1);
+    TEST_ASSERT_EQUAL(2, result);
+}
 
-    /* act */
-    result = convert(2);
+void test_multiply(void)
+{
+    doulbe result = multiply(1, 2);
+    TEST_ASSERT_EQUAL(2, result);
+}
+
+void test_divide(void)
+{
+    doulbe result = divide(4, 2);
+    TEST_ASSERT_EQUAL(2, result);
 
-    /* assert */
+    doulbe result1 = divide(4, 0);
+    TEST_ASSERT_EQUAL(0, result1);
 }
 
 #endif // TEST