Avoid Price.toString() failing for certain values of numerator/denominator.

app/src/main/java/org/gnucash/android/model/Price.java

@@ -4,6 +4,7 @@
 
 
 import java.math.BigDecimal;
+import java.math.MathContext;
 import java.sql.Timestamp;
 import java.text.DecimalFormat;
 import java.text.NumberFormat;
@@ -156,6 +157,6 @@ public String toString() {
         BigDecimal denominator = new BigDecimal(mValueDenom);
         DecimalFormat formatter = (DecimalFormat) NumberFormat.getNumberInstance();
         formatter.setMaximumFractionDigits(6);
-        return formatter.format(numerator.divide(denominator));
+        return formatter.format(numerator.divide(denominator, MathContext.DECIMAL32));
     }
 }

app/src/test/java/org/gnucash/android/test/unit/model/PriceTest.java

@@ -23,6 +23,7 @@
 import java.util.Locale;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.Assert.fail;
 
 
 public class PriceTest {
@@ -52,6 +53,26 @@ public void toString_shouldUseDefaultLocale() {
         assertThat(price.toString()).isEqualTo("1,234");
     }
 
+    /**
+     * BigDecimal throws an ArithmeticException if it can't represent exactly
+     * a result. This can happen with divisions like 1/3 if no precision and
+     * round mode is specified with a MathContext.
+     */
+    @Test
+    public void toString_shouldNotFailForInfinitelyLongDecimalExpansion() {
+        long numerator = 1;
+        long denominator = 3;
+        Price price = new Price();
+
+        price.setValueNum(numerator);
+        price.setValueDenom(denominator);
+        try {
+            price.toString();
+        } catch (ArithmeticException e) {
+            fail("The numerator/denominator division in Price.toString() should not fail.");
+        }
+    }
+
     @Test
     public void getNumerator_shouldReduceAutomatically() {
         long numerator = 1;