added test, removed foobar from min test - derp

json-path/src/main/java/com/jayway/jsonpath/internal/function/numeric/AbstractAggregation.java

@@ -43,17 +43,15 @@ public abstract class AbstractAggregation implements PathFunction {
                     next(value);
                 }
             }
-            return getValue();
         }
-        else if (parameters != null) {
+        if (parameters != null) {
             for (Parameter param : parameters) {
                 if (param.getCachedValue() instanceof Number) {
                     Number value = (Number)param.getCachedValue();
                     next(value);
                 }
             }
-            return getValue();
         }
-        return null;
+        return getValue();
     }
 }

json-path/src/main/java/com/jayway/jsonpath/internal/path/PathCompiler.java

@@ -223,6 +223,20 @@ public class PathCompiler {
         return path.currentIsTail() || readNextToken(appender);
     }
 
+    /**
+     * Parse the parameters of a function call, either the caller has supplied JSON data, or the caller has supplied
+     * another path expression which must be evaluated and in turn invoked against the root document.  In this tokenizer
+     * we're only concerned with parsing the path thus the output of this function is a list of parameters with the Path
+     * set if the parameter is an expression.  If the parameter is a JSON document then the value of the cachedValue is
+     * set on the object.
+     *
+     * @param readPosition
+     *      The current position within the stream we've advanced - TODO remove the need for this...
+     * @return
+     *      An ordered list of parameters that are to processed via the function.  Typically functions either process
+     *      an array of values and/or can consume parameters in addition to the values provided from the consumption of
+     *      an array.
+     */
     private List<Parameter> parseFunctionParameters(int readPosition) {
         PathToken currentToken;
         List<Parameter> parameters = new ArrayList<Parameter>();
@@ -230,7 +244,7 @@ public class PathCompiler {
         Boolean insideParameter = false;
         int braceCount = 0, parenCount = 1;
         while (path.inBounds(readPosition)) {
-            char c = path.charAt(readPosition);
+            char c = path.charAt(readPosition++);
 
             if (c == OPEN_BRACE) {
                 braceCount++;
@@ -273,7 +287,6 @@ public class PathCompiler {
                     parameter.append(c);
                 }
             }
-            readPosition++;
         }
         path.setPosition(readPosition);
         return parameters;

json-path/src/test/java/com/jayway/jsonpath/internal/function/NestedFunctionTest.java

@@ -28,7 +28,25 @@ public class NestedFunctionTest extends BaseFunctionTest {
     }
 
     @Test
-    public void testAverageOfDoubles() {
-        verifyMathFunction(conf, "$.avg({$.numbers.min()}, {$.numbers.max()})", 5.5);
+    public void testParameterAverageFunctionCall() {
+        verifyMathFunction(conf, "$avg({$.numbers.min()}, {$.numbers.max()})", 5.5);
+    }
+
+    @Test
+    public void testArrayAverageFunctionCall() {
+        verifyMathFunction(conf, "$.numbers.avg()", 5.5);
+    }
+
+    /**
+     * This test calculates the following:
+     *
+     * For each number in $.numbers 1 -> 10 add each number up,
+     * then add 1 (min), 10 (max)
+     *
+     * Alternatively 1+2+3+4+5+6+7+8+9+10+1+10 == 66
+     */
+    @Test
+    public void testArrayAverageFunctionCallWithParameters() {
+        verifyMathFunction(conf, "$.numbers.sum({$.numbers.min()}, {$.numbers.max()})", 66.0);
     }
 }

json-path/src/test/java/com/jayway/jsonpath/internal/function/NumericPathFunctionTest.java

@@ -57,7 +57,7 @@ public class NumericPathFunctionTest extends BaseFunctionTest {
 
     @Test
     public void testMinOfDouble() {
-        verifyMathFunction(conf, "$.numbers.min(foobar)", 1d);
+        verifyMathFunction(conf, "$.numbers.min()", 1d);
     }
 
     @Test