Don't show 100% when number of failures is rounded up (#1110)

Co-Authored-By: Mike Drob <mdrob@apple.com>

pkl-core/src/main/java/org/pkl/core/stdlib/test/report/SimpleReport.java

@@ -17,6 +17,8 @@ package org.pkl.core.stdlib.test.report;
 
 import java.io.IOException;
 import java.io.Writer;
+import java.math.BigDecimal;
+import java.math.RoundingMode;
 import java.util.List;
 import java.util.Locale;
 import java.util.stream.Collectors;
@@ -140,16 +142,18 @@ public final class SimpleReport implements TestReport {
   private void makeStatsLine(
       AnsiStringBuilder sb, String kind, int total, int failed, boolean isFailed) {
     var passed = total - failed;
-    var passRate = total > 0 ? 100.0 * passed / total : 0.0;
+    var passRate = "0.0";
+    if (total > 0) {
+      var passedDecimal = new BigDecimal(passed);
+      var hundred = new BigDecimal(100);
+      var totalPrecise = new BigDecimal(total);
+      passRate =
+          hundred.multiply(passedDecimal).divide(totalPrecise, 1, RoundingMode.DOWN).toString();
+    }
+    var passRateLine = String.format(Locale.ROOT, "%s%% %s pass", passRate, kind);
 
     var color = isFailed ? AnsiCode.RED : AnsiCode.GREEN;
-    sb.append(
-        color,
-        () ->
-            sb.append(String.format(Locale.ROOT, "%.1f%%", passRate))
-                .append(" ")
-                .append(kind)
-                .append(" pass"));
+    sb.append(color, () -> sb.append(passRateLine));
 
     if (isFailed) {
       sb.append(" [").append(failed).append('/').append(total).append(" failed]");

pkl-core/src/test/kotlin/org/pkl/core/stdlib/SimpleReportTest.kt

@@ -0,0 +1,74 @@
+/*
+ * Copyright © 2024-2025 Apple Inc. and the Pkl project authors. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.pkl.core.stdlib
+
+import java.io.StringWriter
+import java.util.*
+import org.assertj.core.api.Assertions.assertThat
+import org.junit.jupiter.api.Test
+import org.pkl.core.TestResults
+import org.pkl.core.TestResults.TestResult
+import org.pkl.core.TestResults.TestSectionResults
+import org.pkl.core.stdlib.test.report.SimpleReport
+
+class SimpleReportTest {
+
+  @Test
+  fun `summarize method should generate correct output`() {
+    var resultsBuilder = TestResults.Builder("module1", "module1")
+    resultsBuilder.setFactsSection(
+      TestSectionResults(
+        TestResults.TestSectionName.FACTS,
+        listOf(
+          TestResult(
+            "example1",
+            321919,
+            listOf(TestResults.Failure("Fact Failure", "failed")),
+            emptyList(),
+            false,
+          )
+        ),
+      )
+    )
+    resultsBuilder.setExamplesSection(
+      TestSectionResults(
+        TestResults.TestSectionName.EXAMPLES,
+        listOf(
+          TestResult(
+            "example1",
+            432525,
+            listOf(TestResults.Failure("Output Mismatch", "does not match")),
+            emptyList(),
+            false,
+          )
+        ),
+      )
+    )
+    val testResults = listOf(resultsBuilder.build())
+
+    val writer = StringWriter()
+    val simpleReport = SimpleReport(false)
+    simpleReport.summarize(testResults, writer)
+
+    val expectedOutput =
+      """
+            0.0% tests pass [2/2 failed], 99.9% asserts pass [2/754444 failed]
+            """
+        .trimIndent()
+
+    assertThat(writer.toString().trimIndent()).isEqualTo(expectedOutput)
+  }
+}

pkl-gradle/src/test/kotlin/org/pkl/gradle/TestsTest.kt

@@ -90,7 +90,7 @@ class TestsTest : AbstractTest() {
                  ^^^^^^^^^^^^^^^^^^
              at test#facts["error"][#1] (file:///file, line x)
 
-      50.0% tests pass [1/2 failed], 66.7% asserts pass [1/3 failed]
+      50.0% tests pass [1/2 failed], 66.6% asserts pass [1/3 failed]
       """
           .trimIndent()
       )
@@ -139,7 +139,7 @@ class TestsTest : AbstractTest() {
                    age = 35
                  }
 
-        60.0% tests pass [2/5 failed], 66.7% asserts pass [3/9 failed]
+        60.0% tests pass [2/5 failed], 66.6% asserts pass [3/9 failed]
         """
           .trimIndent()
       )
@@ -212,7 +212,7 @@ class TestsTest : AbstractTest() {
                    age = 35
                  }
 
-        50.0% tests pass [2/4 failed], 66.7% asserts pass [2/6 failed]
+        50.0% tests pass [2/4 failed], 66.6% asserts pass [2/6 failed]
 
         """
           .trimIndent()