From e4f1916f27c912fdb63bb49c1480b3bf8d92fdd8 Mon Sep 17 00:00:00 2001
From: Steve Ayers <sayers@buf.build>
Date: Tue, 29 Apr 2025 17:47:07 -0400
Subject: [PATCH 1/8] Duration

---
 src/main/java/build/buf/protovalidate/Format.java     | 11 ++---------
 src/test/java/build/buf/protovalidate/FormatTest.java |  8 ++++++++
 2 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/src/main/java/build/buf/protovalidate/Format.java b/src/main/java/build/buf/protovalidate/Format.java
index 80faeb0c..49ce48ee 100644
--- a/src/main/java/build/buf/protovalidate/Format.java
+++ b/src/main/java/build/buf/protovalidate/Format.java
@@ -176,7 +176,7 @@ private static void formatStringSafe(StringBuilder builder, Val val, boolean lis
     } else if (type == TypeEnum.Bytes) {
       formatBytes(builder, val);
     } else if (type == TypeEnum.Duration) {
-      formatDuration(builder, val, listType);
+      formatDuration(builder, val);
     } else if (type == TypeEnum.Timestamp) {
       formatTimestamp(builder, val);
     } else if (type == TypeEnum.List) {
@@ -225,12 +225,8 @@ private static void formatTimestamp(StringBuilder builder, Val val) {
    *
    * @param builder the StringBuilder to append the formatted duration value to.
    * @param val the value to format.
-   * @param listType indicates if the value type is a list.
    */
-  private static void formatDuration(StringBuilder builder, Val val, boolean listType) {
-    if (listType) {
-      builder.append("duration(\"");
-    }
+  private static void formatDuration(StringBuilder builder, Val val) {
     Duration duration = val.convertToNative(Duration.class);
 
     double totalSeconds = duration.getSeconds() + (duration.getNanos() / 1_000_000_000.0);
@@ -238,9 +234,6 @@ private static void formatDuration(StringBuilder builder, Val val, boolean listT
     DecimalFormat format = new DecimalFormat("0.#########");
     builder.append(format.format(totalSeconds));
     builder.append("s");
-    if (listType) {
-      builder.append("\")");
-    }
   }
 
   /**
diff --git a/src/test/java/build/buf/protovalidate/FormatTest.java b/src/test/java/build/buf/protovalidate/FormatTest.java
index a5656505..65212ef7 100644
--- a/src/test/java/build/buf/protovalidate/FormatTest.java
+++ b/src/test/java/build/buf/protovalidate/FormatTest.java
@@ -29,4 +29,12 @@ void largeDecimalValuesAreProperlyFormatted() {
     String formatted = Format.format("%s", val);
     assertThat(formatted).isEqualTo("999999999999");
   }
+
+  @Test
+  void testDurationSecondsOnly() {
+    UintT largeDecimal = UintT.uintOf(999999999999L);
+    ListT val = (ListT) ListT.newValArrayList(null, new Val[] {largeDecimal});
+    String formatted = Format.format("%s", val);
+    assertThat(formatted).isEqualTo("999999999999");
+  }
 }

From 3cab97f1d5f3cd9ae6459c803d92a754f65c8c07 Mon Sep 17 00:00:00 2001
From: Steve Ayers <sayers@buf.build>
Date: Tue, 29 Apr 2025 18:03:43 -0400
Subject: [PATCH 2/8] Add tests for duration format

---
 .../build/buf/protovalidate/FormatTest.java   | 39 +++++++++++++++++--
 1 file changed, 36 insertions(+), 3 deletions(-)

diff --git a/src/test/java/build/buf/protovalidate/FormatTest.java b/src/test/java/build/buf/protovalidate/FormatTest.java
index 65212ef7..470e3153 100644
--- a/src/test/java/build/buf/protovalidate/FormatTest.java
+++ b/src/test/java/build/buf/protovalidate/FormatTest.java
@@ -16,9 +16,11 @@
 
 import static org.assertj.core.api.Assertions.assertThat;
 
+import com.google.protobuf.Duration;
 import org.junit.jupiter.api.Test;
 import org.projectnessie.cel.common.types.ListT;
 import org.projectnessie.cel.common.types.UintT;
+import org.projectnessie.cel.common.types.pb.DefaultTypeAdapter;
 import org.projectnessie.cel.common.types.ref.Val;
 
 class FormatTest {
@@ -30,11 +32,42 @@ void largeDecimalValuesAreProperlyFormatted() {
     assertThat(formatted).isEqualTo("999999999999");
   }
 
+  @Test
+  void testDuration() {
+    Duration duration = Duration.newBuilder().setSeconds(123).setNanos(45678).build();
+
+    ListT val =
+        (ListT) ListT.newGenericArrayList(DefaultTypeAdapter.Instance, new Duration[] {duration});
+    String formatted = Format.format("%s", val);
+    assertThat(formatted).isEqualTo("123.000045678s");
+  }
+
+  @Test
+  void testEmptyDuration() {
+    Duration duration = Duration.newBuilder().build();
+    ListT val =
+        (ListT) ListT.newGenericArrayList(DefaultTypeAdapter.Instance, new Duration[] {duration});
+    String formatted = Format.format("%s", val);
+    assertThat(formatted).isEqualTo("0s");
+  }
+
   @Test
   void testDurationSecondsOnly() {
-    UintT largeDecimal = UintT.uintOf(999999999999L);
-    ListT val = (ListT) ListT.newValArrayList(null, new Val[] {largeDecimal});
+    Duration duration = Duration.newBuilder().setSeconds(123).build();
+
+    ListT val =
+        (ListT) ListT.newGenericArrayList(DefaultTypeAdapter.Instance, new Duration[] {duration});
     String formatted = Format.format("%s", val);
-    assertThat(formatted).isEqualTo("999999999999");
+    assertThat(formatted).isEqualTo("123s");
+  }
+
+  @Test
+  void testDurationNanosOnly() {
+    Duration duration = Duration.newBuilder().setNanos(42).build();
+
+    ListT val =
+        (ListT) ListT.newGenericArrayList(DefaultTypeAdapter.Instance, new Duration[] {duration});
+    String formatted = Format.format("%s", val);
+    assertThat(formatted).isEqualTo("0.000000042s");
   }
 }

From ea5ff7217ac5e21471a56446f1e2b4336c12ced8 Mon Sep 17 00:00:00 2001
From: Steve Ayers <sayers@buf.build>
Date: Tue, 29 Apr 2025 18:06:48 -0400
Subject: [PATCH 3/8] Format

---
 conformance/expected-failures.yaml                | 6 ------
 src/main/java/build/buf/protovalidate/Format.java | 8 ++++----
 2 files changed, 4 insertions(+), 10 deletions(-)

diff --git a/conformance/expected-failures.yaml b/conformance/expected-failures.yaml
index 9055e245..8cae39fa 100644
--- a/conformance/expected-failures.yaml
+++ b/conformance/expected-failures.yaml
@@ -24,9 +24,3 @@ kitchen_sink:
   - field/transitive/invalid
   - many/all-non-message-fields/invalid
   - field/invalid
-standard_rules/repeated:
-  - items/in/invalid
-  - items/not_in/invalid
-standard_rules/well_known_types/duration:
-  - in/invalid
-  - not in/invalid
diff --git a/src/main/java/build/buf/protovalidate/Format.java b/src/main/java/build/buf/protovalidate/Format.java
index 49ce48ee..f80d4f4a 100644
--- a/src/main/java/build/buf/protovalidate/Format.java
+++ b/src/main/java/build/buf/protovalidate/Format.java
@@ -147,7 +147,7 @@ private static void formatString(StringBuilder builder, Val val) {
       DecimalFormat format = new DecimalFormat();
       builder.append(format.format(val.value()));
     } else {
-      formatStringSafe(builder, val, false);
+      formatStringSafe(builder, val);
     }
   }
 
@@ -158,7 +158,7 @@ private static void formatString(StringBuilder builder, Val val) {
    * @param val the value to format.
    * @param listType indicates if the value type is a list.
    */
-  private static void formatStringSafe(StringBuilder builder, Val val, boolean listType) {
+  private static void formatStringSafe(StringBuilder builder, Val val) {
     TypeEnum type = val.type().typeEnum();
     if (type == TypeEnum.Bool) {
       builder.append(val.booleanValue());
@@ -172,7 +172,7 @@ private static void formatStringSafe(StringBuilder builder, Val val, boolean lis
       format.setMinimumFractionDigits(6);
       builder.append(format.format(val.value()));
     } else if (type == TypeEnum.String) {
-      builder.append("\"").append(val.value().toString()).append("\"");
+      builder.append(val.value());
     } else if (type == TypeEnum.Bytes) {
       formatBytes(builder, val);
     } else if (type == TypeEnum.Duration) {
@@ -200,7 +200,7 @@ private static void formatList(StringBuilder builder, Val val) {
     List list = val.convertToNative(List.class);
     for (int i = 0; i < list.size(); i++) {
       Object obj = list.get(i);
-      formatStringSafe(builder, DefaultTypeAdapter.nativeToValue(Db.newDb(), null, obj), true);
+      formatStringSafe(builder, DefaultTypeAdapter.nativeToValue(Db.newDb(), null, obj));
       if (i != list.size() - 1) {
         builder.append(", ");
       }

From 4dbc4f38370727d33f562a8ea8982696c6e755ae Mon Sep 17 00:00:00 2001
From: Steve Ayers <sayers@buf.build>
Date: Wed, 30 Apr 2025 11:03:58 -0400
Subject: [PATCH 4/8] Tests

---
 build.gradle.kts                              |  8 ++++
 .../java/build/buf/protovalidate/Format.java  | 34 ++------------
 .../build/buf/protovalidate/FormatTest.java   | 47 ++++++++++++++++++-
 3 files changed, 59 insertions(+), 30 deletions(-)

diff --git a/build.gradle.kts b/build.gradle.kts
index c50440c4..a7d15608 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -207,6 +207,14 @@ allprojects {
     }
     tasks.withType<Test>().configureEach {
         useJUnitPlatform()
+        this.testLogging {
+            this.showStandardStreams = true
+            events("failed")
+            exceptionFormat = org.gradle.api.tasks.testing.logging.TestExceptionFormat.FULL
+            showExceptions = true
+            showCauses = true
+            showStackTraces = true
+        }
     }
 }
 
diff --git a/src/main/java/build/buf/protovalidate/Format.java b/src/main/java/build/buf/protovalidate/Format.java
index f80d4f4a..be3e21fa 100644
--- a/src/main/java/build/buf/protovalidate/Format.java
+++ b/src/main/java/build/buf/protovalidate/Format.java
@@ -144,7 +144,7 @@ private static void formatString(StringBuilder builder, Val val) {
     } else if (val.type().typeEnum() == TypeEnum.Bytes) {
       builder.append(new String((byte[]) val.value(), StandardCharsets.UTF_8));
     } else if (val.type().typeEnum() == TypeEnum.Double) {
-      DecimalFormat format = new DecimalFormat();
+      DecimalFormat format = new DecimalFormat("0.##");
       builder.append(format.format(val.value()));
     } else {
       formatStringSafe(builder, val);
@@ -156,7 +156,6 @@ private static void formatString(StringBuilder builder, Val val) {
    *
    * @param builder the StringBuilder to append the formatted string to.
    * @param val the value to format.
-   * @param listType indicates if the value type is a list.
    */
   private static void formatStringSafe(StringBuilder builder, Val val) {
     TypeEnum type = val.type().typeEnum();
@@ -164,17 +163,6 @@ private static void formatStringSafe(StringBuilder builder, Val val) {
       builder.append(val.booleanValue());
     } else if (type == TypeEnum.Int || type == TypeEnum.Uint) {
       formatDecimal(builder, val);
-    } else if (type == TypeEnum.Double) {
-      // When a double is nested in another type (e.g. a list) it will have a minimum of 6 decimal
-      // digits. This is to maintain consistency with the Go CEL runtime.
-      DecimalFormat format = new DecimalFormat();
-      format.setMaximumFractionDigits(Integer.MAX_VALUE);
-      format.setMinimumFractionDigits(6);
-      builder.append(format.format(val.value()));
-    } else if (type == TypeEnum.String) {
-      builder.append(val.value());
-    } else if (type == TypeEnum.Bytes) {
-      formatBytes(builder, val);
     } else if (type == TypeEnum.Duration) {
       formatDuration(builder, val);
     } else if (type == TypeEnum.Timestamp) {
@@ -236,19 +224,6 @@ private static void formatDuration(StringBuilder builder, Val val) {
     builder.append("s");
   }
 
-  /**
-   * Formats a byte array value.
-   *
-   * @param builder the StringBuilder to append the formatted byte array value to.
-   * @param val the value to format.
-   */
-  private static void formatBytes(StringBuilder builder, Val val) {
-    builder
-        .append("\"")
-        .append(new String((byte[]) val.value(), StandardCharsets.UTF_8))
-        .append("\"");
-  }
-
   /**
    * Formats a hexadecimal value.
    *
@@ -276,9 +251,10 @@ private static void formatHex(StringBuilder builder, Val val, char[] digits) {
    * Formats a decimal value.
    *
    * @param builder the StringBuilder to append the formatted decimal value to.
-   * @param arg the value to format.
+   * @param val the value to format.
    */
-  private static void formatDecimal(StringBuilder builder, Val arg) {
-    builder.append(arg.value());
+  private static void formatDecimal(StringBuilder builder, Val val) {
+    DecimalFormat format = new DecimalFormat("0.#########");
+      builder.append(format.format(val.value()));
   }
 }
diff --git a/src/test/java/build/buf/protovalidate/FormatTest.java b/src/test/java/build/buf/protovalidate/FormatTest.java
index 470e3153..ef0b1fb1 100644
--- a/src/test/java/build/buf/protovalidate/FormatTest.java
+++ b/src/test/java/build/buf/protovalidate/FormatTest.java
@@ -15,17 +15,62 @@
 package build.buf.protovalidate;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
 
 import com.google.protobuf.Duration;
 import org.junit.jupiter.api.Test;
+import org.projectnessie.cel.common.types.DoubleT;
+import org.projectnessie.cel.common.types.Err.ErrException;
 import org.projectnessie.cel.common.types.ListT;
+import org.projectnessie.cel.common.types.StringT;
 import org.projectnessie.cel.common.types.UintT;
 import org.projectnessie.cel.common.types.pb.DefaultTypeAdapter;
 import org.projectnessie.cel.common.types.ref.Val;
 
 class FormatTest {
   @Test
-  void largeDecimalValuesAreProperlyFormatted() {
+  void testNotEnoughArgumentsThrows() {
+    StringT one = StringT.stringOf("one");
+    ListT val = (ListT) ListT.newValArrayList(null, new Val[] {one});
+
+    assertThatThrownBy(
+            () -> {
+              Format.format("first value: %s and  %s", val);
+            })
+        .isInstanceOf(ErrException.class)
+        .hasMessageContaining("format: not enough arguments");
+  }
+
+  @Test
+  void testDouble() {
+    ListT val =
+        (ListT)
+            ListT.newValArrayList(
+                null,
+                new Val[] {
+                  DoubleT.doubleOf(-1.20000000000),
+                  DoubleT.doubleOf(-1.2),
+                  DoubleT.doubleOf(-1.230),
+                  DoubleT.doubleOf(-1.002),
+                  DoubleT.doubleOf(-0.1),
+                  DoubleT.doubleOf(-.1),
+                  DoubleT.doubleOf(-1),
+                  DoubleT.doubleOf(-0.0),
+                  DoubleT.doubleOf(0),
+                  DoubleT.doubleOf(0.0),
+                  DoubleT.doubleOf(1),
+                  DoubleT.doubleOf(0.1),
+                  DoubleT.doubleOf(.1),
+                  DoubleT.doubleOf(1.002),
+                  DoubleT.doubleOf(1.230),
+                  DoubleT.doubleOf(1.20000000000)
+                });
+    String formatted = Format.format("%d, %d, %d, %d, %d, %d, %d, %d, %d, %d, %d, %d, %d, %d, %d, %d", val);
+    assertThat(formatted).isEqualTo("-1.2, -1.2, -1.23, -1.002, -0.1, -0.1, -1, -0, 0, 0, 1, 0.1, 0.1, 1.002, 1.23, 1.2");
+  }
+
+  @Test
+  void testLargeDecimalValuesAreProperlyFormatted() {
     UintT largeDecimal = UintT.uintOf(999999999999L);
     ListT val = (ListT) ListT.newValArrayList(null, new Val[] {largeDecimal});
     String formatted = Format.format("%s", val);

From 26665e1b5b2cd16eda3d00903d05701909a16940 Mon Sep 17 00:00:00 2001
From: Steve Ayers <sayers@buf.build>
Date: Wed, 30 Apr 2025 11:16:07 -0400
Subject: [PATCH 5/8] Adds some additional formatting tests

---
 conformance/expected-failures.yaml            |  5 ---
 .../java/build/buf/protovalidate/Format.java  | 38 ++++++-------------
 2 files changed, 11 insertions(+), 32 deletions(-)

diff --git a/conformance/expected-failures.yaml b/conformance/expected-failures.yaml
index c771d190..17daf1bf 100644
--- a/conformance/expected-failures.yaml
+++ b/conformance/expected-failures.yaml
@@ -15,8 +15,3 @@ custom_rules:
   - field_expression/map/int64/invalid
   - field_expression/map/uint64/valid
   - field_expression/map/uint64/invalid
-kitchen_sink:
-  - field/embedded/invalid
-  - field/transitive/invalid
-  - many/all-non-message-fields/invalid
-  - field/invalid
diff --git a/src/main/java/build/buf/protovalidate/Format.java b/src/main/java/build/buf/protovalidate/Format.java
index be3e21fa..8dd72654 100644
--- a/src/main/java/build/buf/protovalidate/Format.java
+++ b/src/main/java/build/buf/protovalidate/Format.java
@@ -34,6 +34,7 @@
 final class Format {
   private static final char[] HEX_ARRAY = "0123456789ABCDEF".toCharArray();
   private static final char[] LOWER_HEX_ARRAY = "0123456789abcdef".toCharArray();
+private static final DecimalFormat decimalFormat = new DecimalFormat("0.#########");
 
   /**
    * Format the string with a {@link ListT}.
@@ -139,29 +140,14 @@ private static String bytesToHex(byte[] bytes, char[] digits) {
    * @param val the value to format.
    */
   private static void formatString(StringBuilder builder, Val val) {
-    if (val.type().typeEnum() == TypeEnum.String) {
-      builder.append(val.value());
-    } else if (val.type().typeEnum() == TypeEnum.Bytes) {
-      builder.append(new String((byte[]) val.value(), StandardCharsets.UTF_8));
-    } else if (val.type().typeEnum() == TypeEnum.Double) {
-      DecimalFormat format = new DecimalFormat("0.##");
-      builder.append(format.format(val.value()));
-    } else {
-      formatStringSafe(builder, val);
-    }
-  }
-
-  /**
-   * Formats a string value safely for other value types.
-   *
-   * @param builder the StringBuilder to append the formatted string to.
-   * @param val the value to format.
-   */
-  private static void formatStringSafe(StringBuilder builder, Val val) {
     TypeEnum type = val.type().typeEnum();
     if (type == TypeEnum.Bool) {
       builder.append(val.booleanValue());
-    } else if (type == TypeEnum.Int || type == TypeEnum.Uint) {
+    } else if (type == TypeEnum.String) {
+      builder.append(val.value());
+    } else if (type == TypeEnum.Bytes) {
+        builder.append(new String((byte[]) val.value(), StandardCharsets.UTF_8));
+    } else if (type == TypeEnum.Int || type == TypeEnum.Uint || type == TypeEnum.Double) {
       formatDecimal(builder, val);
     } else if (type == TypeEnum.Duration) {
       formatDuration(builder, val);
@@ -170,9 +156,9 @@ private static void formatStringSafe(StringBuilder builder, Val val) {
     } else if (type == TypeEnum.List) {
       formatList(builder, val);
     } else if (type == TypeEnum.Map) {
-      throw new ErrException("unimplemented stringSafe map type");
+      throw new ErrException("unimplemented string map type");
     } else if (type == TypeEnum.Null) {
-      throw new ErrException("unimplemented stringSafe null type");
+      throw new ErrException("unimplemented string null type");
     }
   }
 
@@ -188,7 +174,7 @@ private static void formatList(StringBuilder builder, Val val) {
     List list = val.convertToNative(List.class);
     for (int i = 0; i < list.size(); i++) {
       Object obj = list.get(i);
-      formatStringSafe(builder, DefaultTypeAdapter.nativeToValue(Db.newDb(), null, obj));
+      formatString(builder, DefaultTypeAdapter.nativeToValue(Db.newDb(), null, obj));
       if (i != list.size() - 1) {
         builder.append(", ");
       }
@@ -219,8 +205,7 @@ private static void formatDuration(StringBuilder builder, Val val) {
 
     double totalSeconds = duration.getSeconds() + (duration.getNanos() / 1_000_000_000.0);
 
-    DecimalFormat format = new DecimalFormat("0.#########");
-    builder.append(format.format(totalSeconds));
+    builder.append(decimalFormat.format(totalSeconds));
     builder.append("s");
   }
 
@@ -254,7 +239,6 @@ private static void formatHex(StringBuilder builder, Val val, char[] digits) {
    * @param val the value to format.
    */
   private static void formatDecimal(StringBuilder builder, Val val) {
-    DecimalFormat format = new DecimalFormat("0.#########");
-      builder.append(format.format(val.value()));
+      builder.append(decimalFormat.format(val.value()));
   }
 }

From aefec2ea6b8d19c19a12a847737665889003a5f0 Mon Sep 17 00:00:00 2001
From: Steve Ayers <sayers@buf.build>
Date: Wed, 30 Apr 2025 11:18:58 -0400
Subject: [PATCH 6/8] Adds some additional formatting tests

---
 build.gradle.kts | 1 -
 1 file changed, 1 deletion(-)

diff --git a/build.gradle.kts b/build.gradle.kts
index a7d15608..8f17533e 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -208,7 +208,6 @@ allprojects {
     tasks.withType<Test>().configureEach {
         useJUnitPlatform()
         this.testLogging {
-            this.showStandardStreams = true
             events("failed")
             exceptionFormat = org.gradle.api.tasks.testing.logging.TestExceptionFormat.FULL
             showExceptions = true

From 7b75aaba92a31c77275d6d039adcc930befbe86e Mon Sep 17 00:00:00 2001
From: Steve Ayers <sayers@buf.build>
Date: Wed, 30 Apr 2025 11:22:13 -0400
Subject: [PATCH 7/8] Format

---
 src/main/java/build/buf/protovalidate/Format.java     | 6 +++---
 src/test/java/build/buf/protovalidate/FormatTest.java | 7 +++++--
 2 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/src/main/java/build/buf/protovalidate/Format.java b/src/main/java/build/buf/protovalidate/Format.java
index 8dd72654..81c3c176 100644
--- a/src/main/java/build/buf/protovalidate/Format.java
+++ b/src/main/java/build/buf/protovalidate/Format.java
@@ -34,7 +34,7 @@
 final class Format {
   private static final char[] HEX_ARRAY = "0123456789ABCDEF".toCharArray();
   private static final char[] LOWER_HEX_ARRAY = "0123456789abcdef".toCharArray();
-private static final DecimalFormat decimalFormat = new DecimalFormat("0.#########");
+  private static final DecimalFormat decimalFormat = new DecimalFormat("0.#########");
 
   /**
    * Format the string with a {@link ListT}.
@@ -146,7 +146,7 @@ private static void formatString(StringBuilder builder, Val val) {
     } else if (type == TypeEnum.String) {
       builder.append(val.value());
     } else if (type == TypeEnum.Bytes) {
-        builder.append(new String((byte[]) val.value(), StandardCharsets.UTF_8));
+      builder.append(new String((byte[]) val.value(), StandardCharsets.UTF_8));
     } else if (type == TypeEnum.Int || type == TypeEnum.Uint || type == TypeEnum.Double) {
       formatDecimal(builder, val);
     } else if (type == TypeEnum.Duration) {
@@ -239,6 +239,6 @@ private static void formatHex(StringBuilder builder, Val val, char[] digits) {
    * @param val the value to format.
    */
   private static void formatDecimal(StringBuilder builder, Val val) {
-      builder.append(decimalFormat.format(val.value()));
+    builder.append(decimalFormat.format(val.value()));
   }
 }
diff --git a/src/test/java/build/buf/protovalidate/FormatTest.java b/src/test/java/build/buf/protovalidate/FormatTest.java
index ef0b1fb1..962460a7 100644
--- a/src/test/java/build/buf/protovalidate/FormatTest.java
+++ b/src/test/java/build/buf/protovalidate/FormatTest.java
@@ -65,8 +65,11 @@ void testDouble() {
                   DoubleT.doubleOf(1.230),
                   DoubleT.doubleOf(1.20000000000)
                 });
-    String formatted = Format.format("%d, %d, %d, %d, %d, %d, %d, %d, %d, %d, %d, %d, %d, %d, %d, %d", val);
-    assertThat(formatted).isEqualTo("-1.2, -1.2, -1.23, -1.002, -0.1, -0.1, -1, -0, 0, 0, 1, 0.1, 0.1, 1.002, 1.23, 1.2");
+    String formatted =
+        Format.format("%d, %d, %d, %d, %d, %d, %d, %d, %d, %d, %d, %d, %d, %d, %d, %d", val);
+    assertThat(formatted)
+        .isEqualTo(
+            "-1.2, -1.2, -1.23, -1.002, -0.1, -0.1, -1, -0, 0, 0, 1, 0.1, 0.1, 1.002, 1.23, 1.2");
   }
 
   @Test

From 1453f41f7ccdff910dd4505acef147287a44b31c Mon Sep 17 00:00:00 2001
From: Steve Ayers <sayers@buf.build>
Date: Wed, 30 Apr 2025 13:50:12 -0400
Subject: [PATCH 8/8] Feedback

---
 src/main/java/build/buf/protovalidate/Format.java | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/src/main/java/build/buf/protovalidate/Format.java b/src/main/java/build/buf/protovalidate/Format.java
index 81c3c176..cdc08f50 100644
--- a/src/main/java/build/buf/protovalidate/Format.java
+++ b/src/main/java/build/buf/protovalidate/Format.java
@@ -34,7 +34,6 @@
 final class Format {
   private static final char[] HEX_ARRAY = "0123456789ABCDEF".toCharArray();
   private static final char[] LOWER_HEX_ARRAY = "0123456789abcdef".toCharArray();
-  private static final DecimalFormat decimalFormat = new DecimalFormat("0.#########");
 
   /**
    * Format the string with a {@link ListT}.
@@ -143,11 +142,11 @@ private static void formatString(StringBuilder builder, Val val) {
     TypeEnum type = val.type().typeEnum();
     if (type == TypeEnum.Bool) {
       builder.append(val.booleanValue());
-    } else if (type == TypeEnum.String) {
+    } else if (type == TypeEnum.String || type == TypeEnum.Int || type == TypeEnum.Uint) {
       builder.append(val.value());
     } else if (type == TypeEnum.Bytes) {
       builder.append(new String((byte[]) val.value(), StandardCharsets.UTF_8));
-    } else if (type == TypeEnum.Int || type == TypeEnum.Uint || type == TypeEnum.Double) {
+    } else if (type == TypeEnum.Double) {
       formatDecimal(builder, val);
     } else if (type == TypeEnum.Duration) {
       formatDuration(builder, val);
@@ -205,7 +204,8 @@ private static void formatDuration(StringBuilder builder, Val val) {
 
     double totalSeconds = duration.getSeconds() + (duration.getNanos() / 1_000_000_000.0);
 
-    builder.append(decimalFormat.format(totalSeconds));
+    DecimalFormat formatter = new DecimalFormat("0.#########");
+    builder.append(formatter.format(totalSeconds));
     builder.append("s");
   }
 
@@ -239,6 +239,7 @@ private static void formatHex(StringBuilder builder, Val val, char[] digits) {
    * @param val the value to format.
    */
   private static void formatDecimal(StringBuilder builder, Val val) {
-    builder.append(decimalFormat.format(val.value()));
+    DecimalFormat formatter = new DecimalFormat("0.#########");
+    builder.append(formatter.format(val.value()));
   }
 }