diff --git a/src/main/java/org/jenkinsci/plugins/badge/extensions/BuildParameterRunSelectorExtension.java b/src/main/java/org/jenkinsci/plugins/badge/extensions/BuildParameterRunSelectorExtension.java
index 3de3b791..9b011580 100644
--- a/src/main/java/org/jenkinsci/plugins/badge/extensions/BuildParameterRunSelectorExtension.java
+++ b/src/main/java/org/jenkinsci/plugins/badge/extensions/BuildParameterRunSelectorExtension.java
@@ -97,7 +97,7 @@ private Run findSpecific(Job job, Run run, String what, String specific) {
                                         (specific.equals("Failed")      && isCompleted && isFailed) ||
                                         (specific.equals("Unstable")    && isCompleted && isUnstable) ||
                                         (specific.equals("Unsuccessful") && isCompleted && isUnsuccessful) ||
-                                        (specific.equals("isStable")    && isCompleted && isStable);    
+                                        (specific.equals("Stable")    && isCompleted && isStable);
                         }
                     }
 
diff --git a/src/test/java/org/jenkinsci/plugins/badge/extensions/BuildParameterRunSelectorExtensionTest.java b/src/test/java/org/jenkinsci/plugins/badge/extensions/BuildParameterRunSelectorExtensionTest.java
new file mode 100644
index 00000000..79b5e568
--- /dev/null
+++ b/src/test/java/org/jenkinsci/plugins/badge/extensions/BuildParameterRunSelectorExtensionTest.java
@@ -0,0 +1,132 @@
+package org.jenkinsci.plugins.badge.extensions;
+
+import hudson.model.Job;
+import hudson.model.Result;
+import hudson.model.Run;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.mockito.Mockito;
+
+import static org.hamcrest.CoreMatchers.is;
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.junit.jupiter.api.Assertions.*;
+import static org.mockito.Mockito.when;
+
+class BuildParameterRunSelectorExtensionTest {
+
+    private BuildParameterRunSelectorExtension extension;
+    private Job mockProject;
+    private Run mockRun;
+
+    @BeforeEach
+    void setUp() {
+
+        extension = new BuildParameterRunSelectorExtension();
+        mockProject = Mockito.mock(Job.class);
+        mockRun = Mockito.mock(Run.class);
+    }
+
+    @Test
+    void shouldSelectLastBuild() {
+        when(mockProject.getLastBuild()).thenReturn(mockRun);
+        Run actualRun = extension.select(mockProject, "last", null);
+        assertThat(actualRun, is(mockRun));
+    }
+
+    @Test
+    void shouldSelectFirstBuild() {
+        when(mockProject.getFirstBuild()).thenReturn(mockRun);
+        when(mockRun.getNextBuild()).thenReturn(mockRun);
+        Run actualRun = extension.select(mockProject, "first", null);
+        assertThat(actualRun, is(mockRun));
+    }
+
+    @Test
+    void shouldSelectLastFailedBuild() {
+        when(mockProject.getLastFailedBuild()).thenReturn(mockRun);
+        Run actualRun = extension.select(mockProject, "lastFailed", null);
+        assertThat(actualRun, is(mockRun));
+    }
+    @Test
+    void shouldSelectFirstFailedBuild() {
+        when(mockProject.getFirstBuild()).thenReturn(mockRun);
+        when(mockRun.getNextBuild()).thenReturn(mockRun);
+        when(mockRun.getResult()).thenReturn(Result.FAILURE);
+        Run actualRun = extension.select(mockProject, "firstFailed", null);
+        assertThat(actualRun, is(mockRun));
+    }
+    @Test
+    void shouldSelectLastSuccessfulBuild() {
+        when(mockProject.getLastSuccessfulBuild()).thenReturn(mockRun);
+        Run actualRun = extension.select(mockProject, "lastSuccessful", null);
+        assertThat(actualRun, is(mockRun));
+    }
+    @Test
+    void shouldSelectFirstSuccessfulBuild() {
+        when(mockProject.getFirstBuild()).thenReturn(mockRun);
+        when(mockRun.getNextBuild()).thenReturn(mockRun);
+        when(mockRun.getResult()).thenReturn(Result.SUCCESS);
+        Run actualRun = extension.select(mockProject, "firstSuccessful", null);
+        assertThat(actualRun, is(mockRun));
+    }
+    @Test
+    void shouldSelectLastUnsuccessfulBuild() {
+        when(mockProject.getLastUnsuccessfulBuild()).thenReturn(mockRun);
+        Run actualRun = extension.select(mockProject, "lastUnsuccessful", null);
+        assertThat(actualRun, is(mockRun));
+    }
+    @Test
+    void shouldSelectFirstUnsuccessfulBuild() {
+        when(mockProject.getFirstBuild()).thenReturn(mockRun);
+        when(mockRun.getNextBuild()).thenReturn(mockRun);
+        when(mockRun.getResult()).thenReturn(Result.FAILURE);
+        Run actualRun = extension.select(mockProject, "firstUnsuccessful", null);
+        assertThat(actualRun, is(mockRun));
+    }
+
+    @Test
+    void shouldSelectLastStableBuild() {
+        when(mockProject.getLastStableBuild()).thenReturn(mockRun);
+        Run actualRun = extension.select(mockProject, "lastStable", null);
+        assertThat(actualRun, is(mockRun));
+    }
+    @Test
+    void shouldSelectFirstStableBuild() {
+        when(mockProject.getFirstBuild()).thenReturn(mockRun);
+        when(mockRun.getNextBuild()).thenReturn(mockRun);
+        when(mockRun.getResult()).thenReturn(Result.SUCCESS);
+        Run actualRun = extension.select(mockProject, "firstStable", null);
+        assertThat(actualRun, is(mockRun));
+    }
+
+    @Test
+    void shouldSelectLastUnstableBuild() {
+        when(mockProject.getLastUnstableBuild()).thenReturn(mockRun);
+        Run actualRun = extension.select(mockProject, "lastUnstable", null);
+        assertThat(actualRun, is(mockRun));
+    }
+    @Test
+    void shouldSelectFirstUnstableBuild() {
+        when(mockProject.getFirstBuild()).thenReturn(mockRun);
+        when(mockRun.getNextBuild()).thenReturn(mockRun);
+        when(mockRun.getResult()).thenReturn(Result.UNSTABLE);
+        Run actualRun = extension.select(mockProject, "firstUnstable", null);
+        assertThat(actualRun, is(mockRun));
+    }
+
+    @Test
+    void shouldSelectLastCompletedBuild() {
+        when(mockProject.getLastCompletedBuild()).thenReturn(mockRun);
+        Run actualRun = extension.select(mockProject, "lastCompleted", null);
+        assertThat(actualRun, is(mockRun));
+    }
+    @Test
+    void shouldSelectFirstCompletedBuild() {
+        when(mockProject.getFirstBuild()).thenReturn(mockRun);
+        when(mockRun.getNextBuild()).thenReturn(mockRun);
+        when(mockRun.getResult()).thenReturn(Result.UNSTABLE);
+        Run actualRun = extension.select(mockProject, "firstCompleted", null);
+        assertThat(actualRun, is(mockRun));
+    }
+
+}
\ No newline at end of file