diff --git a/javatests/com/googlesource/gerrit/plugins/supermanifest/JiriSuperManifestIT.java b/javatests/com/googlesource/gerrit/plugins/supermanifest/JiriSuperManifestIT.java
index aef9f78..f5bfbe2 100644
--- a/javatests/com/googlesource/gerrit/plugins/supermanifest/JiriSuperManifestIT.java
+++ b/javatests/com/googlesource/gerrit/plugins/supermanifest/JiriSuperManifestIT.java
@@ -15,6 +15,8 @@
 package com.googlesource.gerrit.plugins.supermanifest;
 
 import static com.google.common.truth.Truth.assertThat;
+import static com.google.common.truth.Truth.assert_;
+import static com.google.gerrit.testing.GerritJUnit.assertThrows;
 import static java.nio.charset.StandardCharsets.UTF_8;
 
 import com.google.gerrit.acceptance.GitUtil;
@@ -128,12 +130,7 @@
 
     BranchApi branch = gApi.projects().name(superKey.get()).branch("refs/heads/destbranch");
     assertThat(branch.file("project1").getContentType()).isEqualTo("x-git/gitlink; charset=UTF-8");
-    try {
-      branch.file("project2");
-      fail("wanted exception");
-    } catch (ResourceNotFoundException e) {
-      // all fine.
-    }
+    assertThrows(ResourceNotFoundException.class, () -> branch.file("project2"));
 
     xml =
         "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n"
@@ -157,8 +154,8 @@
         .to("refs/heads/srcbranch")
         .assertOkStatus();
 
-    branch = gApi.projects().name(superKey.get()).branch("refs/heads/destbranch");
-    assertThat(branch.file("project2").getContentType()).isEqualTo("x-git/gitlink; charset=UTF-8");
+    BranchApi branch2 = gApi.projects().name(superKey.get()).branch("refs/heads/destbranch");
+    assertThat(branch2.file("project2").getContentType()).isEqualTo("x-git/gitlink; charset=UTF-8");
 
     // Make sure config change gets picked up.
     pushConfig(
@@ -189,8 +186,8 @@
         .to("refs/heads/srcbranch")
         .assertOkStatus();
 
-    branch = gApi.projects().name(superKey.get()).branch("refs/heads/other");
-    assertThat(branch.file("project3").getContentType()).isEqualTo("x-git/gitlink; charset=UTF-8");
+    BranchApi branch3 = gApi.projects().name(superKey.get()).branch("refs/heads/other");
+    assertThat(branch3.file("project3").getContentType()).isEqualTo("x-git/gitlink; charset=UTF-8");
   }
 
   @Test
@@ -356,12 +353,7 @@
     assertThat(branch.file("project1").getContentType()).isEqualTo("x-git/gitlink; charset=UTF-8");
     assertThat(branch.file("manifest2").getContentType()).isEqualTo("x-git/gitlink; charset=UTF-8");
     assertThat(branch.file("manifest2").asString()).contains(commit.name());
-    try {
-      branch.file("project2");
-      fail("wanted exception");
-    } catch (ResourceNotFoundException e) {
-      // all fine.
-    }
+    assertThrows(ResourceNotFoundException.class, () -> branch.file("project2"));
   }
 
   @Test
@@ -454,12 +446,7 @@
     BranchApi branch = gApi.projects().name(superKey.get()).branch("refs/heads/destbranch");
     assertThat(branch.file("project1").getContentType()).isEqualTo("x-git/gitlink; charset=UTF-8");
     assertThat(branch.file("manifest2").getContentType()).isEqualTo("x-git/gitlink; charset=UTF-8");
-    try {
-      branch.file("project2");
-      fail("wanted exception");
-    } catch (ResourceNotFoundException e) {
-      // all fine.
-    }
+    assertThrows(ResourceNotFoundException.class, () -> branch.file("project2"));
   }
 
   private void outer() throws Exception {
@@ -471,17 +458,13 @@
   }
 
   private void innerTest() throws Exception {
-    try {
-      outer();
-      fail("should throw");
-    } catch (IllegalStateException e) {
-      StackTraceElement[] trimmed =
-          SuperManifestRefUpdatedListener.trimStack(
-              e.getStackTrace(), Thread.currentThread().getStackTrace()[1]);
-      String str = Arrays.toString(trimmed);
-      assertThat(str).doesNotContain("trimStackTrace");
-      assertThat(str).contains("innerTest");
-    }
+    IllegalStateException thrown = assertThrows(IllegalStateException.class, () -> outer());
+    StackTraceElement[] trimmed =
+        SuperManifestRefUpdatedListener.trimStack(
+            thrown.getStackTrace(), Thread.currentThread().getStackTrace()[1]);
+    String str = Arrays.toString(trimmed);
+    assertThat(str).doesNotContain("trimStackTrace");
+    assertThat(str).contains("innerTest");
   }
 
   @Test
@@ -546,21 +529,11 @@
 
     BranchApi branch1 = gApi.projects().name(superKey.get()).branch("refs/heads/src1");
     assertThat(branch1.file("project1").getContentType()).isEqualTo("x-git/gitlink; charset=UTF-8");
-    try {
-      branch1.file("project2");
-      fail("wanted exception");
-    } catch (ResourceNotFoundException e) {
-      // all fine.
-    }
+    assertThrows(ResourceNotFoundException.class, () -> branch1.file("project2"));
 
     BranchApi branch2 = gApi.projects().name(superKey.get()).branch("refs/heads/src2");
     assertThat(branch2.file("project2").getContentType()).isEqualTo("x-git/gitlink; charset=UTF-8");
-    try {
-      branch2.file("project1");
-      fail("wanted exception");
-    } catch (ResourceNotFoundException e) {
-      // all fine.
-    }
+    assertThrows(ResourceNotFoundException.class, () -> branch2.file("project1"));
   }
 
   @Test
@@ -764,12 +737,7 @@
         .assertOkStatus();
 
     BranchApi branch = gApi.projects().name(superKey.get()).branch("refs/heads/master");
-    try {
-      branch.file("project1");
-      fail("wanted exception");
-    } catch (ResourceNotFoundException e) {
-      // all fine.
-    }
+    assertThrows(ResourceNotFoundException.class, () -> branch.file("project1"));
   }
 
   /*
@@ -779,7 +747,7 @@
     String got = JiriUpdater.relativize(URI.create(a), URI.create(b)).toString();
 
     if (!got.equals(want)) {
-      fail(String.format("relative('%s', '%s') = '%s', want '%s'", a, b, got, want));
+      assert_().fail("relative('%s', '%s') = '%s', want '%s'", a, b, got, want);
     }
   }
 
diff --git a/javatests/com/googlesource/gerrit/plugins/supermanifest/RepoSuperManifestIT.java b/javatests/com/googlesource/gerrit/plugins/supermanifest/RepoSuperManifestIT.java
index 3f012c6..2db98ec 100644
--- a/javatests/com/googlesource/gerrit/plugins/supermanifest/RepoSuperManifestIT.java
+++ b/javatests/com/googlesource/gerrit/plugins/supermanifest/RepoSuperManifestIT.java
@@ -15,6 +15,7 @@
 package com.googlesource.gerrit.plugins.supermanifest;
 
 import static com.google.common.truth.Truth.assertThat;
+import static com.google.gerrit.testing.GerritJUnit.assertThrows;
 import static java.nio.charset.StandardCharsets.UTF_8;
 
 import com.google.gerrit.acceptance.GitUtil;
@@ -122,12 +123,7 @@
 
     BranchApi branch = gApi.projects().name(superKey.get()).branch("refs/heads/destbranch");
     assertThat(branch.file("project1").getContentType()).isEqualTo("x-git/gitlink; charset=UTF-8");
-    try {
-      branch.file("project2");
-      fail("wanted exception");
-    } catch (ResourceNotFoundException e) {
-      // all fine.
-    }
+    assertThrows(ResourceNotFoundException.class, () -> branch.file("project2"));
 
     xml =
         "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n"
@@ -147,8 +143,8 @@
         .to("refs/heads/srcbranch")
         .assertOkStatus();
 
-    branch = gApi.projects().name(superKey.get()).branch("refs/heads/destbranch");
-    assertThat(branch.file("project2").getContentType()).isEqualTo("x-git/gitlink; charset=UTF-8");
+    BranchApi branch2 = gApi.projects().name(superKey.get()).branch("refs/heads/destbranch");
+    assertThat(branch2.file("project2").getContentType()).isEqualTo("x-git/gitlink; charset=UTF-8");
 
     // Make sure config change gets picked up.
     pushConfig(
@@ -177,8 +173,8 @@
         .to("refs/heads/srcbranch")
         .assertOkStatus();
 
-    branch = gApi.projects().name(superKey.get()).branch("refs/heads/other");
-    assertThat(branch.file("project3").getContentType()).isEqualTo("x-git/gitlink; charset=UTF-8");
+    BranchApi branch3 = gApi.projects().name(superKey.get()).branch("refs/heads/other");
+    assertThat(branch3.file("project3").getContentType()).isEqualTo("x-git/gitlink; charset=UTF-8");
   }
 
   @Test
@@ -363,17 +359,13 @@
   }
 
   private void innerTest() throws Exception {
-    try {
-      outer();
-      fail("should throw");
-    } catch (IllegalStateException e) {
-      StackTraceElement[] trimmed =
-          SuperManifestRefUpdatedListener.trimStack(
-              e.getStackTrace(), Thread.currentThread().getStackTrace()[1]);
-      String str = Arrays.toString(trimmed);
-      assertThat(str).doesNotContain("trimStackTrace");
-      assertThat(str).contains("innerTest");
-    }
+    IllegalStateException thrown = assertThrows(IllegalStateException.class, () -> outer());
+    StackTraceElement[] trimmed =
+        SuperManifestRefUpdatedListener.trimStack(
+            thrown.getStackTrace(), Thread.currentThread().getStackTrace()[1]);
+    String str = Arrays.toString(trimmed);
+    assertThat(str).doesNotContain("trimStackTrace");
+    assertThat(str).contains("innerTest");
   }
 
   @Test
@@ -438,21 +430,11 @@
 
     BranchApi branch1 = gApi.projects().name(superKey.get()).branch("refs/heads/src1");
     assertThat(branch1.file("project1").getContentType()).isEqualTo("x-git/gitlink; charset=UTF-8");
-    try {
-      branch1.file("project2");
-      fail("wanted exception");
-    } catch (ResourceNotFoundException e) {
-      // all fine.
-    }
+    assertThrows(ResourceNotFoundException.class, () -> branch1.file("project2"));
 
     BranchApi branch2 = gApi.projects().name(superKey.get()).branch("refs/heads/src2");
     assertThat(branch2.file("project2").getContentType()).isEqualTo("x-git/gitlink; charset=UTF-8");
-    try {
-      branch2.file("project1");
-      fail("wanted exception");
-    } catch (ResourceNotFoundException e) {
-      // all fine.
-    }
+    assertThrows(ResourceNotFoundException.class, () -> branch2.file("project1"));
   }
 
   @Test