[Frontend-go] Add interface unit test (#1975)

* [Frontend-go] Add interface unit test

Signed-off-by: Arthur Chan <arthur.chan@adalogics.com>

* Fix formatting

Signed-off-by: Arthur Chan <arthur.chan@adalogics.com>

---------

Signed-off-by: Arthur Chan <arthur.chan@adalogics.com>

src/fuzz_introspector/frontends/frontend_go.py

@@ -609,11 +609,19 @@ def _process_call_expr_child(
         # Package/method call
         if call_child.type == 'selector_expression':
             target_name = call_child.text.decode()
-
             # Variable call
             split_call = target_name.split('.')
             if len(split_call) > 1:
-                var_name = self.var_map.get(split_call[-2])
+                # For indexing selector
+                if '[' in split_call[-2] and ']' in split_call[-2]:
+                    var_name = self.var_map.get(split_call[-2].split('[')[0])
+                    if var_name:
+                        if '[' in var_name and ']' in var_name:
+                            var_name = var_name.split(']')[-1]
+                        elif var_name == 'string':
+                            var_name = 'uint8'
+                else:
+                    var_name = self.var_map.get(split_call[-2])
                 if var_name:
                     target_name = f'{var_name}.{split_call[-1]}'
 
@@ -692,12 +700,6 @@ def extract_local_variable_type(self,
                                                           'FunctionMethod']):
         """Gets the local variable types of the function."""
 
-        query = self.tree_sitter_lang.query('( var_declaration ) @vd')
-        for _, exprs in query.captures(self.root).items():
-            for decl_node in exprs:
-                # TODO Handle long variable declaration
-                pass
-
         query = self.tree_sitter_lang.query('( short_var_declaration ) @vd')
         for _, exprs in query.captures(self.root).items():
             for decl_node in exprs:
@@ -713,6 +715,31 @@ def extract_local_variable_type(self,
                 if decl_name and decl_type:
                     self.var_map[decl_name] = decl_type
 
+        query = self.tree_sitter_lang.query('( for_statement ) @fd')
+        for _, exprs in query.captures(self.root).items():
+            for for_node in exprs:
+                for child in for_node.children:
+                    if child.type == 'range_clause':
+                        left = child.child_by_field_name('left')
+                        right = child.child_by_field_name('right')
+
+                        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()]
+                            if '[' in decl_type and ']' in decl_type:
+                                decl_type = decl_type.split(']', 1)[-1]
+                            elif decl_type == 'string':
+                                decl_type = 'uint8'
+                        else:
+                            decl_type = self._detect_variable_type(
+                                right, all_funcs_meths)
+
+                        if decl_name and decl_type:
+                            self.var_map[decl_name] = decl_type
+
     def extract_callsites(self, all_funcs_meths: dict[str, 'FunctionMethod']):
         """Gets the callsites of the function."""
 
@@ -735,9 +762,8 @@ def extract_callsites(self, all_funcs_meths: dict[str, 'FunctionMethod']):
                         call_expr.start_point.row + 1,
                     ))
 
-        callsites = sorted(callsites, key=lambda x: x[1][1])
+        callsites = sorted(callsites, key=lambda x: x[1][0])
         self.base_callsites = [(x[0], x[2]) for x in callsites]
-
         # Process detailed callsites
         for dst, src_line in self.base_callsites:
             src_loc = self.parent_source.source_file + ':%d,1' % (src_line)

src/test/data/source-code/go/test-project-5/fuzzer.go

@@ -0,0 +1,81 @@
+// 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 shapes
+
+import (
+	"testing"
+	"strconv"
+)
+
+type Shape interface {
+	Area() float64
+}
+
+type Circle struct {
+	Radius float64
+}
+
+func (c Circle) Area() float64 {
+	return 3.14 * c.Radius * c.Radius
+}
+
+func (c Circle) Perimeter() float64 {
+	return 2 * 3.14 * c.Radius
+}
+
+type Rectangle struct {
+	Width, Height float64
+}
+
+func (r Rectangle) Area() float64 {
+	return r.Width * r.Height
+}
+
+func (r Rectangle) Perimeter() float64 {
+	return 2 * (r.Width + r.Height)
+}
+
+func FuzzShapes(f *testing.F) {
+	f.Fuzz(func(t *testing.T, radiusString, widthString, heightString 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
+		}
+
+		shapes := []Shape{
+			Circle{Radius: radius},
+			Rectangle{Width: width, Height: height},
+		}
+
+		for _, shape := range shapes {
+			_ = shape.Area()
+		}
+
+		for i := 0; i < len(shapes); i++ {
+			_ = shapes[i].Perimeter()
+		}
+	})
+}

src/test/test_frontends_go.py

@@ -109,6 +109,10 @@ def test_tree_sitter_go_sample4():
 
 
 def test_tree_sitter_go_sample5():
+    """
+    Similar to test_tree_sitter_rust_sample2, it is not able to
+    deteremine what instance the item is used until runtime.
+    """
     project = oss_fuzz.analyse_folder(
         'go',
         'src/test/data/source-code/go/test-project-5',
@@ -117,7 +121,14 @@ def test_tree_sitter_go_sample5():
 
     # 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 'strconv.ParseFloat' in functions_reached
+    assert 'Shape.Area' in functions_reached
+    assert 'Shape.Perimeter' in functions_reached
 
 
 def test_tree_sitter_go_sample6():