Add systematic test for if statements

testdata/instrumenter/IfStmt.go

@@ -2,21 +2,42 @@ package instrumenter
 
 // https://go.dev/ref/spec#If_statements
 
-// TODO: Add systematic tests.
-
-// The condition from an if statement is always a boolean expression.
-// And even if the condition is a simple variable, it is wrapped.
-// This is different from arguments to function calls, where simple
-// variables are not wrapped.
-func ifStmt(a int, b string, c bool) bool {
-	if a > 0 && b == "positive" {
+func ifStmt(i int, s string, cond bool) bool {
+
+	if i > 0 && s == "positive" {
 		return true
 	}
-	if len(b) > 5 {
-		return len(b) > 10
+
+	if len(s) > 5 {
+		return len(s) > 10
 	}
-	if c {
+
+	// The condition from an if statement is always a boolean expression.
+	// And even if the condition is a simple variable, it is wrapped.
+	// This is different from arguments to function calls, where simple
+	// variables are not wrapped.
+	if cond {
 		return true
 	}
+
+	// An if statement, like a switch statement, can have an initializer
+	// statement. Other than in a switch statement, the condition in an if
+	// statement is used exactly once, so there is no need to introduce a new
+	// variable. Therefore, no complicated rewriting is needed.
+
+	if i++; cond {
+		return i > 5
+	}
+
+	if i := i + 1; cond {
+		return i > 6
+	}
+
+	// Conditions in the initializer are instrumented as well.
+	// TODO: Instrument the initialization before the condition.
+	if cond := i > 7; cond {
+		return i > 8
+	}
+
 	return false
 }

testdata/instrumenter/IfStmt.gobco

@@ -1,21 +1,44 @@
 package instrumenter
 
-func ifStmt(a int, b string, c bool) bool {
-	if gobcoCover(0, gobcoCover(1, a > 0) && gobcoCover(2, b == "positive")) {
+func ifStmt(i int, s string, cond bool) bool {
+
+	if gobcoCover(0, gobcoCover(1, i > 0) && gobcoCover(2, s == "positive")) {
 		return true
 	}
-	if gobcoCover(3, len(b) > 5) {
-		return gobcoCover(4, len(b) > 10)
+
+	if gobcoCover(3, len(s) > 5) {
+		return gobcoCover(4, len(s) > 10)
 	}
-	if gobcoCover(5, c) {
+
+	if gobcoCover(5, cond) {
 		return true
 	}
+
+	if i++; gobcoCover(6, cond) {
+		return gobcoCover(7, i > 5)
+	}
+
+	if i := i + 1; gobcoCover(8, cond) {
+		return gobcoCover(9, i > 6)
+	}
+
+	if cond := gobcoCover(11, i > 7); gobcoCover(10, cond) {
+		return gobcoCover(12, i > 8)
+	}
+
 	return false
 }
 
-// :12:5: "a > 0 && b == \"positive\""
-// :12:5: "a > 0"
-// :12:14: "b == \"positive\""
-// :15:5: "len(b) > 5"
-// :16:10: "len(b) > 10"
-// :18:5: "c"
+// :7:5: "i > 0 && s == \"positive\""
+// :7:5: "i > 0"
+// :7:14: "s == \"positive\""
+// :11:5: "len(s) > 5"
+// :12:10: "len(s) > 10"
+// :19:5: "cond"
+// :28:10: "cond"
+// :29:10: "i > 5"
+// :32:17: "cond"
+// :33:10: "i > 6"
+// :38:20: "cond"
+// :38:13: "i > 7"
+// :39:10: "i > 8"