JS: Add metric for uncalled functions

Author: asger-semmle

javascript/ql/src/meta/analysis-quality/CallGraphQuality.qll

@@ -40,6 +40,14 @@ class RelevantInvoke extends InvokeNode {
   RelevantInvoke() { not getFile() instanceof IgnoredFile }
 }
 
+/** An call site that is relevant for analysis quality. */
+class RelevantFunction extends Function {
+  RelevantFunction() {
+    not getFile() instanceof IgnoredFile and
+    hasBody() // ignore abstract or ambient functions
+  }
+}
+
 /**
  * Holds if `name` is a the name of an external module.
  */
@@ -136,7 +144,7 @@ SourceNode externalNode() {
 }
 
 /**
- * Gets a data flow node that can be resolved to a callback.
+ * Gets a data flow node that can be resolved to a function, usually a callback.
  *
  * These are not part of the static call graph, but the data flow analysis can
  * track them, so we consider them resolved.
@@ -150,6 +158,26 @@ SourceNode resolvableCallback() {
   )
 }
 
+/**
+ * Gets a data flow node that can be resolved to an invocation of a callback.
+ *
+ * These are not part of the static call graph, but the data flow analysis can
+ * track them, so we consider them resolved.
+ */
+SourceNode nodeLeadingToInvocation() {
+  exists(result.getAnInvocation())
+  or
+  exists(Node arg |
+    FlowSteps::argumentPassing(_, arg, _, nodeLeadingToInvocation()) and
+    result.flowsTo(arg)
+  )
+  or
+  exists(AdditionalPartialInvokeNode invoke, Node arg |
+    invoke.isPartialArgument(arg, _, _) and
+    result.flowsTo(arg)
+  )
+}
+
 /**
  * A call site that can be resolved to a function in the same project.
  */
@@ -205,3 +233,23 @@ class NonExternalCall extends RelevantInvoke {
     not this instanceof ExternalCall
   }
 }
+
+/**
+ * A function with at least one call site.
+ */
+class FunctionWithCallers extends RelevantFunction {
+  FunctionWithCallers() {
+    FlowSteps::calls(_, this)
+    or
+    this = nodeLeadingToInvocation().getAstNode()
+  }
+}
+
+/**
+ * A function without any call sites.
+ */
+class FunctionWithoutCallers extends RelevantFunction {
+  FunctionWithoutCallers() {
+    not this instanceof FunctionWithCallers
+  }
+}

javascript/ql/src/meta/analysis-quality/CalledFunctionCandidates.ql

@@ -0,0 +1,14 @@
+/**
+ * @name Called function candidates
+ * @description The number of functions for which finding call sites is relevant
+*               for analysis quality.
+ * @kind metric
+ * @metricType project
+ * @metricAggregate sum
+ * @tags meta
+ * @id js/meta/called-function-candidates
+ */
+import javascript
+import CallGraphQuality
+
+select projectRoot(), count(RelevantFunction f)

javascript/ql/src/meta/analysis-quality/CalledFunctionRatio.ql

@@ -0,0 +1,13 @@
+/**
+ * @name Called function ratio
+ * @description The percentage of relevant functions for which a call site was found.
+ * @kind metric
+ * @metricType project
+ * @metricAggregate sum min max avg
+ * @tags meta
+ * @id js/meta/called-function-ratio
+ */
+import javascript
+import CallGraphQuality
+
+select projectRoot(), 100.0 * count(FunctionWithCallers f) / (float) count(RelevantFunction f)

javascript/ql/src/meta/analysis-quality/CalledFunctions.ql

@@ -0,0 +1,13 @@
+/**
+ * @name Called functions
+ * @description The number of functions for which a call site was found.
+ * @kind metric
+ * @metricType project
+ * @metricAggregate sum
+ * @tags meta
+ * @id js/meta/called-functions
+ */
+import javascript
+import CallGraphQuality
+
+select projectRoot(), count(FunctionWithCallers f)

javascript/ql/src/meta/analysis-quality/UncalledFunctions.ql

@@ -0,0 +1,13 @@
+/**
+ * @name Uncalled functions
+ * @description The number of functions for which no call site could be found.
+ * @kind metric
+ * @metricType project
+ * @metricAggregate sum
+ * @tags meta
+ * @id js/meta/uncalled-functions
+ */
+import javascript
+import CallGraphQuality
+
+select projectRoot(), count(FunctionWithoutCallers f)