[Frontend-go] Add unit test for channels and goroutine

src/fuzz_introspector/frontends/frontend_go.py

@@ -662,6 +662,7 @@ def _detect_variable_type(
                 args = child.child_by_field_name('arguments')
                 target_name = self._process_call_expr_child(
                     call, all_funcs_meths)
+
                 if target_name in all_funcs_meths:
                     return all_funcs_meths[target_name].return_type
 
@@ -670,6 +671,16 @@ def _detect_variable_type(
                         if arg.type.endswith('identifier'):
                             return arg.text.decode()
 
+                elif target_name == 'make':
+                    for arg in args.children:
+                        type_node = arg.child_by_field_name('value')
+                        if type_node:
+                            return type_node.text.decode()
+
+                        type_node = arg.child_by_field_name('element')
+                        if type_node:
+                            return type_node.text.decode()
+
             # Selector expression
             elif child.type == 'selector_expression':
                 target_name = self._process_call_expr_child(
@@ -705,6 +716,8 @@ def extract_local_variable_type(self,
             for decl_node in exprs:
                 left = decl_node.child_by_field_name('left')
                 right = decl_node.child_by_field_name('right')
+                if not left or not right:
+                    continue
 
                 for child in left.children:
                     if child.type == 'identifier':
@@ -722,13 +735,16 @@ def extract_local_variable_type(self,
                     if child.type == 'range_clause':
                         left = child.child_by_field_name('left')
                         right = child.child_by_field_name('right')
+                        if not left or not right:
+                            continue
 
                         for left_child in left.children:
                             if left_child.type == 'identifier':
                                 decl_name = left_child.text.decode()
 
                         if right.type == 'identifier':
-                            decl_type = self.var_map[right.text.decode()]
+                            decl_type = self.var_map.get(
+                                right.text.decode(), '')
                             if '[' in decl_type and ']' in decl_type:
                                 decl_type = decl_type.split(']', 1)[-1]
                             elif decl_type == 'string':

src/test/data/source-code/go/test-project-6/fuzzer.go

@@ -0,0 +1,74 @@
+// 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 channels
+
+import (
+	"fmt"
+	"testing"
+	"time"
+)
+
+type Square struct {
+	Side float64
+}
+
+type Circle struct {
+	Radius float64
+}
+
+func (s Square) Describe() string {
+	return fmt.Sprintf("Square with side length %.2f", s.Side)
+}
+
+func (c Circle) Describe() string {
+	return fmt.Sprintf("Circle with radius %.2f", c.Radius)
+}
+
+func unreachableGoroutine() {
+	ch := make(chan Square)
+
+	go func() {
+		square := Square{Side: 4.0}
+		ch <- square
+		close(ch)
+	}()
+
+	for shape := range ch {
+		fmt.Println(shape.Describe())
+	}
+}
+
+func FuzzChannels(f *testing.F) {
+	f.Fuzz(func(t *testing.T, durationString string) {
+		duration, err := time.ParseDuration(durationString)
+		if err != nil || duration < 0 {
+			return
+		}
+
+		ch := make(chan Circle)
+
+		go func() {
+			time.Sleep(duration)
+			circle := Circle{Radius: 5.5}
+			ch <- circle
+			close(ch)
+		}()
+
+		for shape := range ch {
+			fmt.Println(shape.Describe())
+		}
+	})
+}

src/test/test_frontends_go.py

@@ -140,7 +140,15 @@ def test_tree_sitter_go_sample6():
 
     # 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 'Circle.Describe' in functions_reached
+    assert 'time.Sleep' in functions_reached
+    assert 'Square.Describe' not in functions_reached
+    assert 'unreachableGoroutine' not in functions_reached
 
 
 def test_tree_sitter_go_sample7():