Also check that pipeline jobs aren't running

Don't allow to start a build if there is something still building.

src/main/java/in/ashwanthkumar/gocd/github/GitHubPRBuildPlugin.java

@@ -14,6 +14,7 @@
 import com.tw.go.plugin.model.Revision;
 import com.tw.go.plugin.util.ListUtil;
 import com.tw.go.plugin.util.StringUtil;
+import in.ashwanthkumar.gocd.github.jsonapi.PipelineHistory;
 import in.ashwanthkumar.gocd.github.jsonapi.PipelineStatus;
 import in.ashwanthkumar.gocd.github.jsonapi.Server;
 import in.ashwanthkumar.gocd.github.jsonapi.ServerFactory;
@@ -371,20 +372,26 @@ GoPluginApiResponse handleLatestRevisionSince(GoPluginApiRequest goPluginApiRequ
         }
     }
 
-    private boolean canSchedule(Server server, Option<String> pipelineName) throws IOException {
-        if (pipelineName.isEmpty()) {
+    boolean canSchedule(Server server, Option<String> pipelineNameOption) throws IOException {
+        if (pipelineNameOption.isEmpty()) {
             LOGGER.debug("Pipeline name not given. Can schedule");
             return true;
         }
 
-        LOGGER.info(String.format("Check can schedule pipeline %s", pipelineName.get()));
+        final String pipelineName = pipelineNameOption.get();
 
-        PipelineStatus pipelineStatus = server.getPipelineStatus(pipelineName.get());
+        LOGGER.info(String.format("Check can schedule pipeline %s", pipelineName));
+
+        PipelineStatus pipelineStatus = server.getPipelineStatus(pipelineName);
         if (pipelineStatus != null) {
-            LOGGER.info(String.format("  Pipeline schedulable: %s", pipelineStatus.schedulable));
-            return pipelineStatus.schedulable;
+            if (pipelineStatus.schedulable) {
+                PipelineHistory pipelineHistory = server.getPipelineHistory(pipelineName);
+                return pipelineHistory == null
+                        || !pipelineHistory.isPipelineRunningOrScheduled();
+            } else {
+                return false;
+            }
         } else {
-            LOGGER.debug("  Could not fetch pipeline status. Allow to schedule");
             return true;
         }
     }

src/main/java/in/ashwanthkumar/gocd/github/jsonapi/PipelineHistory.java

@@ -20,7 +20,7 @@ public List<Pipeline> getPipelines() {
         return pipelines;
     }
 
-    boolean isPipelineRunningOrScheduled() {
+    public boolean isPipelineRunningOrScheduled() {
         for (Pipeline pipeline : pipelines) {
             if (pipeline.isRunningOrScheduled()) {
                 return true;

src/main/java/in/ashwanthkumar/gocd/github/jsonapi/PipelineStatus.java

@@ -7,4 +7,10 @@ public class PipelineStatus {
     @SerializedName("schedulable")
     public boolean schedulable;
 
+    public PipelineStatus() {
+    }
+
+    public PipelineStatus(boolean schedulable) {
+        this.schedulable = schedulable;
+    }
 }

src/test/java/in/ashwanthkumar/gocd/github/GitHubPRBuildPluginTest.java

@@ -10,6 +10,7 @@
 import com.tw.go.plugin.model.GitConfig;
 import com.tw.go.plugin.model.ModifiedFile;
 import com.tw.go.plugin.model.Revision;
+import in.ashwanthkumar.gocd.github.jsonapi.PipelineHistory;
 import in.ashwanthkumar.gocd.github.jsonapi.PipelineStatus;
 import in.ashwanthkumar.gocd.github.jsonapi.Server;
 import in.ashwanthkumar.gocd.github.jsonapi.ServerFactory;
@@ -21,6 +22,7 @@
 import in.ashwanthkumar.gocd.github.util.GitFactory;
 import in.ashwanthkumar.gocd.github.util.GitFolderFactory;
 import in.ashwanthkumar.gocd.github.util.JSONUtils;
+import in.ashwanthkumar.utils.lang.option.Option;
 import org.apache.commons.io.FileUtils;
 import org.junit.After;
 import org.junit.Before;
@@ -252,6 +254,107 @@ public void shouldBuildBlacklistedBranchIfBlacklistingNotEnabled() throws Except
         assertThat(response.responseCode(), is(200));
     }
 
+    @Test
+    public void shouldSchedule() throws Exception {
+        GitFactory gitFactory = mock(GitFactory.class);
+        GitFolderFactory gitFolderFactory = mock(GitFolderFactory.class);
+        GitHubPRBuildPlugin plugin = new GitHubPRBuildPlugin(
+                new GerritProvider(),
+                gitFactory,
+                gitFolderFactory,
+                mockServerFactory(),
+                mockGoApplicationAccessor()
+        );
+
+        Server server = mock(Server.class);
+        when(server.getPipelineStatus("pipeline")).thenReturn(new PipelineStatus(true));
+        PipelineHistory pipelineHistory = mockPipelineHistory(false);
+        when(server.getPipelineHistory("pipeline")).thenReturn(pipelineHistory);
+
+        assertThat(plugin.canSchedule(server, Option.option("pipeline")), is(true));
+    }
+
+    @Test
+    public void shouldNotScheduleIfPipelineNotSchedulable() throws Exception {
+        GitFactory gitFactory = mock(GitFactory.class);
+        GitFolderFactory gitFolderFactory = mock(GitFolderFactory.class);
+        GitHubPRBuildPlugin plugin = new GitHubPRBuildPlugin(
+                new GerritProvider(),
+                gitFactory,
+                gitFolderFactory,
+                mockServerFactory(),
+                mockGoApplicationAccessor()
+        );
+
+        Server server = mock(Server.class);
+        when(server.getPipelineStatus("pipeline")).thenReturn(new PipelineStatus(false));
+        PipelineHistory pipelineHistory = mockPipelineHistory(false);
+        when(server.getPipelineHistory("pipeline")).thenReturn(pipelineHistory);
+
+        assertThat(plugin.canSchedule(server, Option.option("pipeline")), is(false));
+    }
+
+    @Test
+    public void shouldNotScheduleIfPipelineHistoryContainsRunningJobs() throws Exception {
+        GitFactory gitFactory = mock(GitFactory.class);
+        GitFolderFactory gitFolderFactory = mock(GitFolderFactory.class);
+        GitHubPRBuildPlugin plugin = new GitHubPRBuildPlugin(
+                new GerritProvider(),
+                gitFactory,
+                gitFolderFactory,
+                mockServerFactory(),
+                mockGoApplicationAccessor()
+        );
+
+        Server server = mock(Server.class);
+        when(server.getPipelineStatus("pipeline")).thenReturn(new PipelineStatus(true));
+        PipelineHistory pipelineHistory = mockPipelineHistory(true);
+        when(server.getPipelineHistory("pipeline")).thenReturn(pipelineHistory);
+
+        assertThat(plugin.canSchedule(server, Option.option("pipeline")), is(false));
+    }
+
+    @Test
+    public void shouldScheduleIfNoPipelineStatusFound() throws Exception {
+        GitFactory gitFactory = mock(GitFactory.class);
+        GitFolderFactory gitFolderFactory = mock(GitFolderFactory.class);
+        GitHubPRBuildPlugin plugin = new GitHubPRBuildPlugin(
+                new GerritProvider(),
+                gitFactory,
+                gitFolderFactory,
+                mockServerFactory(),
+                mockGoApplicationAccessor()
+        );
+
+        Server server = mock(Server.class);
+
+        assertThat(plugin.canSchedule(server, Option.option("pipeline")), is(true));
+    }
+
+    @Test
+    public void shouldScheduleIfNoPipelineHistoryFound() throws Exception {
+        GitFactory gitFactory = mock(GitFactory.class);
+        GitFolderFactory gitFolderFactory = mock(GitFolderFactory.class);
+        GitHubPRBuildPlugin plugin = new GitHubPRBuildPlugin(
+                new GerritProvider(),
+                gitFactory,
+                gitFolderFactory,
+                mockServerFactory(),
+                mockGoApplicationAccessor()
+        );
+
+        Server server = mock(Server.class);
+        when(server.getPipelineStatus("pipeline")).thenReturn(new PipelineStatus(true));
+
+        assertThat(plugin.canSchedule(server, Option.option("pipeline")), is(true));
+    }
+
+    private PipelineHistory mockPipelineHistory(boolean isRunning) {
+        PipelineHistory pipelineHistory = mock(PipelineHistory.class);
+        when(pipelineHistory.isPipelineRunningOrScheduled()).thenReturn(isRunning);
+        return pipelineHistory;
+    }
+
     private GoPluginApiRequest mockRequest() {
         GoPluginApiRequest request = mock(GoPluginApiRequest.class);
         when(request.requestBody()).thenReturn("{\n" +