convertToMulti: Compare unit bases to this.base

This is a necessary precondition for the conversion methods used later
on in convertToMutliple, and it is simpler than the existing method.
I can also be sure it works, due to the tests I just wrote.

1 files changed, 2 insertions, 3 deletions

diff --git a/src/main/java/sevenUnits/unit/LinearUnitValue.java b/src/main/java/sevenUnits/unit/LinearUnitValue.java
index a8848fc..e239b49 100644
--- a/src/main/java/sevenUnits/unit/LinearUnitValue.java
+++ b/src/main/java/sevenUnits/unit/LinearUnitValue.java
@@ -126,11 +126,10 @@ public final class LinearUnitValue {
 			final List<LinearUnit> others) {
 		if (others.size() < 1)
 			throw new IllegalArgumentException("Must have at least one unit");
-		final ObjectProduct<BaseUnit> unitBase = others.get(0).getBase();
 		for (final LinearUnit unit : others) {
-			if (!unitBase.equals(unit.getBase()))
+			if (!Objects.equals(this.unit.getBase(), unit.getBase()))
 				throw new IllegalArgumentException(
-						"All units must have the same base.");
+						"All provided units must have the same base as the value.");
 		}
 		
 		LinearUnitValue remaining = this;