From 1759fffe6cc6bae69152da719ef98764f123c249 Mon Sep 17 00:00:00 2001
From: Ulli Hafner <ullrich.hafner@gmail.com>
Date: Sun, 3 Nov 2024 16:55:05 +0100
Subject: [PATCH] Improve exception handling if metric is missing.

---
 src/main/java/edu/hm/hafner/coverage/Metric.java     | 7 ++++++-
 src/test/java/edu/hm/hafner/coverage/MetricTest.java | 8 ++++++++
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/src/main/java/edu/hm/hafner/coverage/Metric.java b/src/main/java/edu/hm/hafner/coverage/Metric.java
index 745e834..d27acb3 100644
--- a/src/main/java/edu/hm/hafner/coverage/Metric.java
+++ b/src/main/java/edu/hm/hafner/coverage/Metric.java
@@ -8,6 +8,8 @@
 import java.util.TreeSet;
 import java.util.stream.Stream;
 
+import org.apache.commons.lang3.StringUtils;
+
 import com.google.errorprone.annotations.Immutable;
 
 import edu.hm.hafner.coverage.Coverage.CoverageBuilder;
@@ -79,7 +81,10 @@ public static Metric fromName(final String name) {
                 return metric;
             }
         }
-        throw new IllegalArgumentException("No metric found for name: " + name);
+        if (StringUtils.isBlank(name)) {
+            throw new IllegalArgumentException("No metric defined");
+        }
+        throw new IllegalArgumentException("No metric found for name '" + name + "'");
     }
 
     private static String normalize(final String name) {
diff --git a/src/test/java/edu/hm/hafner/coverage/MetricTest.java b/src/test/java/edu/hm/hafner/coverage/MetricTest.java
index 5a0cafd..980c40d 100644
--- a/src/test/java/edu/hm/hafner/coverage/MetricTest.java
+++ b/src/test/java/edu/hm/hafner/coverage/MetricTest.java
@@ -23,6 +23,14 @@ void shouldMapFromName(final String name) {
         assertThat(Metric.fromName(name)).isSameAs(Metric.CYCLOMATIC_COMPLEXITY);
     }
 
+    @Test
+    void shouldProvideContextWhenMetricIsWrong() {
+        assertThatIllegalArgumentException().isThrownBy(() -> Metric.fromName("undefined"))
+                .withMessageContaining("No metric found for name 'undefined'");
+        assertThatIllegalArgumentException().isThrownBy(() -> Metric.fromName(""))
+                .withMessageContaining("No metric defined");
+    }
+
     @EnumSource(Metric.class)
     @ParameterizedTest(name = "{0} should be converted to a tag name and then back to a metric")
     void shouldConvertToTags(final Metric metric) {