Fix not used variables not detected in IF (#1104)

docs/releasenotes/unreleased/fixes.2.rst

@@ -0,0 +1,11 @@
+unused-variable not detected within IF block (#1093)
+----------------------------------------------------
+
+If the variable was defined in the IF block, I0920 ``unused-variable`` was not reported even if variable was not used
+anywhere::
+
+    *** Test Cases ***
+    Useless variable definition
+        IF    True
+             ${not_used}    Keyword Call
+        END

robocop/checkers/misc.py

@@ -1343,12 +1343,28 @@ def visit_If(self, node):  # noqa
         self.variables.append({})
         for item in node.body:
             self.visit(item)
-        self.variables.pop()
+        self.add_variables_from_if_to_scope()
         if node.orelse:
             self.visit(node.orelse)
         for token in node.header.get_tokens(Token.ASSIGN):
             self.handle_assign_variable(token)
 
+    def add_variables_from_if_to_scope(self):
+        """
+        Add all variables in given IF branch to common scope. If variable is used already in the branch, if it will
+        also be mark as used.
+        """
+        variables = self.variables.pop()
+        if not self.variables:
+            self.variables.append(variables)
+            return
+        for var_name, cached_var in variables.items():
+            if var_name in self.variables[-1]:
+                if cached_var.is_used:
+                    self.variables[-1][var_name].is_used = True
+            else:
+                self.variables[-1][var_name] = cached_var
+
     def visit_LibraryImport(self, node):  # noqa
         for token in node.get_tokens(Token.NAME, Token.ARGUMENT):
             self.find_not_nested_variable(token.value, is_var=False)

tests/atest/rules/misc/unused_variable/expected_output_after_var.txt

@@ -2,10 +2,13 @@ test.robot:15:5:15:11 [I] 0920 Variable '${var}' is assigned but not used
 test.robot:19:15:19:22 [I] 0920 Variable '${var2}' is assigned but not used
 test.robot:23:5:23:11 [I] 0920 Variable '${var}' is assigned but not used
 test.robot:31:5:31:14 [I] 0920 Variable '${assign}' is assigned but not used
-test.robot:42:12:42:18 [I] 0920 Variable '${var}' is assigned but not used
-test.robot:68:12:68:23 [I] 0920 Variable '${category}' is assigned but not used
-test.robot:116:5:116:11 [I] 0920 Variable '${var}' is assigned but not used
-test.robot:119:5:119:14 [I] 0920 Variable '${assign}' is assigned but not used
-test.robot:122:12:122:23 [I] 0920 Variable '${not_used}' is assigned but not used
-test.robot:130:12:130:23 [I] 0920 Variable '${variable}' is assigned but not used
+test.robot:39:9:39:20 [I] 0920 Variable '${not_used}' is assigned but not used
+test.robot:44:9:44:32 [I] 0920 Variable '${not_used_from_branch}' is assigned but not used
+test.robot:52:13:52:30 [I] 0920 Variable '${nested_define3}' is assigned but not used
+test.robot:66:12:66:18 [I] 0920 Variable '${var}' is assigned but not used
+test.robot:92:12:92:23 [I] 0920 Variable '${category}' is assigned but not used
+test.robot:140:5:140:11 [I] 0920 Variable '${var}' is assigned but not used
+test.robot:143:5:143:14 [I] 0920 Variable '${assign}' is assigned but not used
+test.robot:146:12:146:23 [I] 0920 Variable '${not_used}' is assigned but not used
+test.robot:154:12:154:23 [I] 0920 Variable '${variable}' is assigned but not used
 unused_section_vars.robot:21:1:21:19 [I] 0920 Variable '${GLOBAL_NOT_USED}' is assigned but not used

tests/atest/rules/misc/unused_variable/expected_output_pre_var.txt

@@ -2,8 +2,11 @@ test.robot:15:5:15:11 [I] 0920 Variable '${var}' is assigned but not used
 test.robot:19:15:19:22 [I] 0920 Variable '${var2}' is assigned but not used
 test.robot:23:5:23:11 [I] 0920 Variable '${var}' is assigned but not used
 test.robot:31:5:31:14 [I] 0920 Variable '${assign}' is assigned but not used
-test.robot:42:12:42:18 [I] 0920 Variable '${var}' is assigned but not used
-test.robot:68:12:68:23 [I] 0920 Variable '${category}' is assigned but not used
-test.robot:116:5:116:11 [I] 0920 Variable '${var}' is assigned but not used
-test.robot:119:5:119:14 [I] 0920 Variable '${assign}' is assigned but not used
+test.robot:39:9:39:20 [I] 0920 Variable '${not_used}' is assigned but not used
+test.robot:44:9:44:32 [I] 0920 Variable '${not_used_from_branch}' is assigned but not used
+test.robot:52:13:52:30 [I] 0920 Variable '${nested_define3}' is assigned but not used
+test.robot:66:12:66:18 [I] 0920 Variable '${var}' is assigned but not used
+test.robot:92:12:92:23 [I] 0920 Variable '${category}' is assigned but not used
+test.robot:140:5:140:11 [I] 0920 Variable '${var}' is assigned but not used
+test.robot:143:5:143:14 [I] 0920 Variable '${assign}' is assigned but not used
 unused_section_vars.robot:21:1:21:19 [I] 0920 Variable '${GLOBAL_NOT_USED}' is assigned but not used

tests/atest/rules/misc/unused_variable/expected_output_rf3.txt

@@ -0,0 +1,12 @@
+test.robot:15:5:15:11 [I] 0920 Variable '${var}' is assigned but not used
+test.robot:19:15:19:22 [I] 0920 Variable '${var2}' is assigned but not used
+test.robot:23:5:23:11 [I] 0920 Variable '${var}' is assigned but not used
+test.robot:31:5:31:14 [I] 0920 Variable '${assign}' is assigned but not used
+test.robot:39:9:39:20 [I] 0920 Variable '${not_used}' is assigned but not used
+test.robot:44:9:44:32 [I] 0920 Variable '${not_used_from_branch}' is assigned but not used
+test.robot:56:13:56:30 [I] 0920 Variable '${nested_define3}' is assigned but not used
+test.robot:66:12:66:18 [I] 0920 Variable '${var}' is assigned but not used
+test.robot:92:12:92:23 [I] 0920 Variable '${category}' is assigned but not used
+test.robot:140:5:140:11 [I] 0920 Variable '${var}' is assigned but not used
+test.robot:143:5:143:14 [I] 0920 Variable '${assign}' is assigned but not used
+unused_section_vars.robot:21:1:21:19 [I] 0920 Variable '${GLOBAL_NOT_USED}' is assigned but not used

tests/atest/rules/misc/unused_variable/test.robot

@@ -34,6 +34,30 @@ Used In IF
     IF    $var
         Keyword    String with ${var2}
     END
+    ${used_in_if}    Keyword
+    IF    True
+        ${not_used}    Keyword
+        # TODO even if branch used it, it should be mark as unused. Could be achieved by making
+        # add_variables_from_if_to_scope temporarily saving popped variables
+        ${used_in_branch}    Keyword
+    ELSE IF    False
+        ${not_used_from_branch}    Keyword    ${used_in_branch}
+    ELSE
+        Keyword    ${used_in_if}
+    END
+    IF    nested
+        IF    nested-loop
+            ${nested_define}    Keyword
+            ${nested_define2}    Keyword
+            ${nested_define3}    Keyword
+        ELSE
+            ${nested_define}    Keyword
+            ${nested_define2}    Keyword
+            ${nested_define3}    Keyword
+        END
+        Keyword    ${nested_define}
+    END
+    Keyword    ${nested_define2}
 
 Not Used From FOR
     FOR    ${var}    IN    1  2  3

tests/atest/rules/misc/unused_variable/test_rule.py

@@ -15,7 +15,15 @@ def test_rule_pre_var(self):
             src_files=["test.robot", "unused_section_vars.robot"],
             expected_file="expected_output_pre_var.txt",
             issue_format="end_col",
-            target_version="<7",
+            target_version=">=4;<7",
+        )
+
+    def test_rule_rf3(self):
+        self.check_rule(
+            src_files=["test.robot", "unused_section_vars.robot"],
+            expected_file="expected_output_rf3.txt",
+            issue_format="end_col",
+            target_version="==3.*",
         )
 
     def test_rule_on_loops(self):