Mods to add getPipelineVariables() support (#431).

src/main/java/org/gitlab4j/api/PipelineApi.java

@@ -752,4 +752,48 @@ public class PipelineApi extends AbstractApi implements Constants {
                 "projects", getProjectIdOrPath(projectIdOrPath), "trigger", "pipeline");
         return (response.readEntity(Pipeline.class));
     }
+
+    /**
+     * Get List of variables of a pipeline.
+     *
+     * <pre><code>GET /projects/:id/pipelines/:pipeline_id/variables</code></pre>
+     *
+     * @param projectIdOrPath projectIdOrPath the project in the form of an Integer(ID), String(path), or Project instance, required
+     * @param pipelineId the pipeline ID
+     * @return a List of pipeline variables
+     * @throws GitLabApiException if any exception occurs
+     */
+    public List<Variable> getPipelineVariables(Object projectIdOrPath, Integer pipelineId) throws GitLabApiException {
+        return (getPipelineVariables(projectIdOrPath, pipelineId, getDefaultPerPage()).all());
+    }
+
+    /**
+     * Get a Pager of variables of a pipeline.
+     *
+     * <pre><code>GET /projects/:id/pipelines/:pipeline_id/variables</code></pre>
+     *
+     * @param projectIdOrPath projectIdOrPath the project in the form of an Integer(ID), String(path), or Project instance, required
+     * @param pipelineId the pipeline ID
+     * @param itemsPerPage the number of Pipeline instances that will be fetched per page
+     * @return a Pager of pipeline variables
+     * @throws GitLabApiException if any exception occurs
+     */
+    public Pager<Variable> getPipelineVariables(Object projectIdOrPath, Integer pipelineId, int itemsPerPage) throws GitLabApiException {
+        return (new Pager<Variable>(this, Variable.class, itemsPerPage, null, 
+                "projects",  getProjectIdOrPath(projectIdOrPath), "pipelines", pipelineId, "variables"));
+    }
+
+    /**
+     * Get a Stream of variables of a pipeline as a Stream.
+     *
+     * <pre><code>GET /projects/:id/pipelines/:pipeline_id/variables</code></pre>
+     *
+     * @param projectIdOrPath projectIdOrPath the project in the form of an Integer(ID), String(path), or Project instance, required
+     * @param pipelineId the pipeline ID
+     * @return a Stream of pipeline variables
+     * @throws GitLabApiException if any exception occurs
+     */
+    public Stream<Variable> getPipelineVariablesStream(Object projectIdOrPath, Integer pipelineId) throws GitLabApiException {
+        return (getPipelineVariables(projectIdOrPath, pipelineId, getDefaultPerPage()).stream());
+    }
 }

src/test/java/org/gitlab4j/api/TestGitLabApiBeans.java

@@ -312,6 +312,12 @@ public class TestGitLabApiBeans {
         assertTrue(compareJson(pipelineSchedule, "pipeline-schedule.json"));
     }
 
+    @Test
+    public void testPipelineVariables() throws Exception {
+        List<Variable> variables = unmarshalResourceList(Variable.class, "pipeline-variables.json");
+        assertTrue(compareJson(variables, "pipeline-variables.json"));
+    }
+
     @Test
     public void testProjectVariables() throws Exception {
         List<Variable> variables = unmarshalResourceList(Variable.class, "project-variables.json");

src/test/java/org/gitlab4j/api/TestPipelineApi.java

 package org.gitlab4j.api;
 
 import static java.util.stream.Collectors.toList;
+import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertTrue;
@@ -290,4 +291,41 @@ public class TestPipelineApi extends AbstractIntegrationTest {
 
         gitLabApi.getPipelineApi().deletePipeline(testProject, pipeline.getId());
     }
+
+    @Test
+    public void testPipelineVariables() throws GitLabApiException {
+
+        // Skip this test if no .gitlab-ci.yml file is in the test project
+        assumeNotNull(gitlabCiYml);
+
+        // Arrange
+        Map<String, String> variableMap = new HashMap<>();
+        variableMap.put("VAR1", "value1");
+        variableMap.put("VAR2", "value2");
+
+        // Act
+        Pipeline pipeline = gitLabApi.getPipelineApi().createPipeline(testProject, "master", variableMap);
+
+        // Assert
+        assertNotNull(pipeline);
+
+        try {
+
+            Stream<Variable> stream = gitLabApi.getPipelineApi().getPipelineVariablesStream(testProject, pipeline.getId());
+            stream.forEach(v -> {
+                String value = variableMap.get(v.getKey());
+                assertEquals(value, v.getValue());
+            });
+
+            List<Variable> variables = gitLabApi.getPipelineApi().getPipelineVariables(testProject, pipeline.getId());
+            assertEquals(variableMap.size(), variables.size());
+            variables.forEach(v -> {
+                String value = variableMap.get(v.getKey());
+                assertEquals(value, v.getValue());
+            });
+
+        } finally {
+            gitLabApi.getPipelineApi().deletePipeline(testProject, pipeline.getId());
+        }
+    }
 }

src/test/resources/org/gitlab4j/api/pipeline-variables.json

+[
+  {
+    "key": "RUN_NIGHTLY_BUILD",
+    "variable_type": "env_var",
+    "value": "true"
+  },
+  {
+    "key": "foo",
+    "value": "bar"
+  }
+]
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