diff --git a/tests/search/grouping_adv/answers/istrue-1.json b/tests/search/grouping_adv/answers/istrue-1.json
new file mode 100644
index 000000000..4f5551da6
--- /dev/null
+++ b/tests/search/grouping_adv/answers/istrue-1.json
@@ -0,0 +1,59 @@
+{
+  "root": {
+    "id": "toplevel",
+    "relevance": 1.0,
+    "fields": {
+      "totalCount": 28
+    },
+    "coverage": {
+      "coverage": 100,
+      "documents": 28,
+      "full": true,
+      "nodes": 2,
+      "results": 1,
+      "resultsFull": 1
+    },
+    "children": [
+      {
+        "id": "group:root:0",
+        "relevance": 1.0,
+        "continuation": {
+          "this": ""
+        },
+        "children": [
+          {
+            "id": "grouplist:a",
+            "relevance": 1.0,
+            "label": "a",
+            "children": [
+              {
+                "id": "group:string:a1",
+                "relevance": 10977.31338339293,
+                "value": "a1",
+                "fields": {
+                  "count()": 5
+                }
+              },
+              {
+                "id": "group:string:a3",
+                "relevance": 10011.709521325834,
+                "value": "a3",
+                "fields": {
+                  "count()": 4
+                }
+              },
+              {
+                "id": "group:string:a2",
+                "relevance": 9998.214537458838,
+                "value": "a2",
+                "fields": {
+                  "count()": 3
+                }
+              }
+            ]
+          }
+        ]
+      }
+    ]
+  }
+}
diff --git a/tests/search/grouping_adv/answers/istrue-2.json b/tests/search/grouping_adv/answers/istrue-2.json
new file mode 100644
index 000000000..c47d5f5af
--- /dev/null
+++ b/tests/search/grouping_adv/answers/istrue-2.json
@@ -0,0 +1,43 @@
+{
+  "root": {
+    "id": "toplevel",
+    "relevance": 1.0,
+    "fields": {
+      "totalCount": 28
+    },
+    "coverage": {
+      "coverage": 100,
+      "documents": 28,
+      "full": true,
+      "nodes": 2,
+      "results": 1,
+      "resultsFull": 1
+    },
+    "children": [
+      {
+        "id": "group:root:0",
+        "relevance": 1.0,
+        "continuation": {
+          "this": ""
+        },
+        "children": [
+          {
+            "id": "grouplist:boool",
+            "relevance": 1.0,
+            "label": "boool",
+            "children": [
+              {
+                "id": "group:bool:true",
+                "relevance": 10977.31338339293,
+                "value": "true",
+                "fields": {
+                  "count()": 12
+                }
+              }
+            ]
+          }
+        ]
+      }
+    ]
+  }
+}
diff --git a/tests/search/grouping_adv/answers/istrue-3.json b/tests/search/grouping_adv/answers/istrue-3.json
new file mode 100644
index 000000000..4fed3250b
--- /dev/null
+++ b/tests/search/grouping_adv/answers/istrue-3.json
@@ -0,0 +1,43 @@
+{
+  "root": {
+    "id": "toplevel",
+    "relevance": 1.0,
+    "fields": {
+      "totalCount": 28
+    },
+    "coverage": {
+      "coverage": 100,
+      "documents": 28,
+      "full": true,
+      "nodes": 2,
+      "results": 1,
+      "resultsFull": 1
+    },
+    "children": [
+      {
+        "id": "group:root:0",
+        "relevance": 1.0,
+        "continuation": {
+          "this": ""
+        },
+        "children": [
+          {
+            "id": "grouplist:a",
+            "relevance": 1.0,
+            "label": "a",
+            "children": [
+              {
+                "id": "group:string:a1",
+                "relevance": 10977.31338339293,
+                "value": "a1",
+                "fields": {
+                  "count()": 5
+                }
+              }
+            ]
+          }
+        ]
+      }
+    ]
+  }
+}
diff --git a/tests/search/grouping_adv/answers/istrue-4.json b/tests/search/grouping_adv/answers/istrue-4.json
new file mode 100644
index 000000000..8f874ffba
--- /dev/null
+++ b/tests/search/grouping_adv/answers/istrue-4.json
@@ -0,0 +1,59 @@
+{
+  "root": {
+    "id": "toplevel",
+    "relevance": 1.0,
+    "fields": {
+      "totalCount": 28
+    },
+    "coverage": {
+      "coverage": 100,
+      "documents": 28,
+      "full": true,
+      "nodes": 2,
+      "results": 1,
+      "resultsFull": 1
+    },
+    "children": [
+      {
+        "id": "group:root:0",
+        "relevance": 1.0,
+        "continuation": {
+          "this": ""
+        },
+        "children": [
+          {
+            "id": "grouplist:a",
+            "relevance": 1.0,
+            "label": "a",
+            "children": [
+              {
+                "id": "group:string:a1",
+                "relevance": 12111.719438207627,
+                "value": "a1",
+                "fields": {
+                  "count()": 5
+                }
+              },
+              {
+                "id": "group:string:a2",
+                "relevance": 11111.709477840308,
+                "value": "a2",
+                "fields": {
+                  "count()": 6
+                }
+              },
+              {
+                "id": "group:string:a3",
+                "relevance": 6985.517516649399,
+                "value": "a3",
+                "fields": {
+                  "count()": 5
+                }
+              }
+            ]
+          }
+        ]
+      }
+    ]
+  }
+}
diff --git a/tests/search/grouping_adv/grouping_base.rb b/tests/search/grouping_adv/grouping_base.rb
index feb8744af..96d1041f5 100644
--- a/tests/search/grouping_adv/grouping_base.rb
+++ b/tests/search/grouping_adv/grouping_base.rb
@@ -21,6 +21,7 @@ def querytest_common
     wait_for_hitcount('query=test&streaming.selection=true', 28, 10)
 
     querytest_filter
+    querytest_istrue_error_handling
 
     # Test quantiles
     check_query('all(group(boool) each(output(quantiles([0.1], f))))', 'quantile-1', 40)
@@ -308,6 +309,11 @@ def querytest_filter
     check_query('all(group(a) each(group(b) filter(regex("c1", c)) each(output(count()))))', 'filter-4')
     check_query('all(group(a) filter(regex("c2", c)) each(group(b) each(output(count()))))', 'filter-5')
     check_query('all(group(a) filter(regex("a1", a)) each(group(b) filter(regex("b1", b)) each(output(count()))))', 'filter-6')
+
+    check_query('all(group(a) filter(istrue(boool)) each(output(count())))', 'istrue-1')
+    check_query('all(group(boool) filter(istrue(boool)) each(output(count())))', 'istrue-2')
+    check_query('all(group(a) filter(istrue(boool) and regex("^a1$", a)) each(output(count())))', 'istrue-3')
+    check_query('all(group(a) filter(not istrue(boool)) each(output(count())))', 'istrue-4')
   end
 
   # Tests that are known to fail
@@ -315,6 +321,14 @@ def querytest_failing_common
     wait_for_hitcount('query=test&streaming.selection=true', 28, 10)
   end
 
+  def querytest_istrue_error_handling
+    result = search('/search/?hits=0&query=sddocname:test&select=all(group(a) filter(istrue(n)) each(output(count())))&restrict=test&streaming.selection=true')
+    puts result
+    assert(result.json['root']['errors'], "Expected error when using istrue with non-boolean field")
+    error_message = result.json['root']['errors'][0]['message']
+    assert_match(/boolean input|filter error/i, error_message, "Expected error message about boolean input or filter error, got: #{error_message}")
+  end
+
   def querytest_global_max
     check_query('all(group(a)max(inf)each(max(inf)each(output(summary()))))', 'global-max-1', DEFAULT_TIMEOUT, false)
     check_query('all(group(a)max(inf)each(each(output(summary()))))', 'global-max-2', DEFAULT_TIMEOUT, false)