[Frontend-go] Add unit testing on combined sample (#1981)

Signed-off-by: Arthur Chan <[email protected]>

src/test/data/source-code/go/test-project-8/fuzzer.go

@@ -0,0 +1,119 @@
+// Copyright 2025 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+package combined
+
+import (
+	"fmt"
+	"strconv"
+	"testing"
+	"time"
+)
+
+type Shape struct {
+	Type   string
+	Radius float64
+	Width  float64
+	Height float64
+}
+
+func (s Shape) Area() float64 {
+	if s.Type == "Circle" {
+		return 3.14 * s.Radius * s.Radius
+	} else if s.Type == "Rectangle" {
+		return s.Width * s.Height
+	}
+	return 0
+}
+
+func (s Shape) Perimeter() float64 {
+	if s.Type == "Circle" {
+		return 2 * 3.14 * s.Radius
+	} else if s.Type == "Rectangle" {
+		return 2 * (s.Width + s.Height)
+	}
+	return 0
+}
+
+type Person struct {
+	Name string
+	Age  int
+}
+
+func (p Person) Greet() string {
+	return fmt.Sprintf("Hello, my name is %s and I am %d years old.", p.Name, p.Age)
+}
+
+func (p Person) GoodBye() string {
+	return fmt.Sprintf("Bye. See you next time.")
+}
+
+func unreachableGoroutine() {
+	for i := 0; i < 5; i++ {
+		processValue(i)
+	}
+}
+
+func processValue(value int) {
+	fmt.Printf("Processing value: %d\n", value)
+}
+
+func FuzzCombined(f *testing.F) {
+	f.Fuzz(func(t *testing.T, radiusString, widthString, heightString, name string, ageString string) {
+		radius, err := strconv.ParseFloat(radiusString, 64)
+		if err != nil {
+			return
+		}
+
+		width, err := strconv.ParseFloat(widthString, 64)
+		if err != nil {
+			return
+		}
+
+		height, err := strconv.ParseFloat(heightString, 64)
+		if err != nil {
+			return
+		}
+
+		age, err := strconv.Atoi(ageString)
+		if err != nil {
+			return
+		}
+
+		shapes := []Shape{
+			{Type: "Circle", Radius: radius},
+			{Type: "Rectangle", Width: width, Height: height},
+		}
+
+		p := Person{Name: name, Age: age}
+
+		ch := make(chan string)
+		go func() {
+			ch <- p.Greet()
+			for _, shape := range shapes {
+				ch <- fmt.Sprintf("Shape: %s, Area: %.2f, Perimeter: %.2f", shape.Type, shape.Area(), shape.Perimeter())
+			}
+			close(ch)
+		}()
+
+		for msg := range ch {
+			fmt.Println(msg)
+		}
+
+		for i := 0; i < len(shapes); i++ {
+			fmt.Printf("Processing shape %d - Area: %.2f\n", i, shapes[i].Area())
+		}
+	})
+}

src/test/test_frontends_go.py

@@ -177,7 +177,18 @@ def test_tree_sitter_go_sample8():
 
     # Project check
     harness = project.get_source_codes_with_harnesses()
-    assert len(harness) == 0
+    assert len(harness) == 1
+
+    functions_reached = project.get_reachable_functions(harness[0].source_file, harness[0])
+
+    # Callsite check
+    assert 'Person.Greet' in functions_reached
+    assert 'Shape.Area' in functions_reached
+    assert 'Shape.Perimeter' in functions_reached
+    assert 'close' in functions_reached
+    assert 'unreachableGoroutine' not in functions_reached
+    assert 'processValue' not in functions_reached
+    assert 'Person.GoodBye' not in functions_reached
 
 
 def test_tree_sitter_go_sample9():