Use ANSI colors for test results; more polish (#771)

Any thrown Pkl Errors are colored in the simple test report!

Also:
* Refactor `TextFormatter` to be more generic; rename to `TextFormattingStringBuilder`
* Adjust test report slightly (no emojis, add more spacing).
* Introduce `ColorTheme` class.
* Make stack frame descriptors colored as "faint"

Also: this changes the summary so it summarizes _all_ modules, rather than a summary per module.

---------

Co-authored-by: Islon Scherer <islonscherer@gmail.com>
Co-authored-by: Philip K.F. Hölzenspies <holzensp@gmail.com>

pkl-core/src/test/kotlin/org/pkl/core/EvaluateTestsTest.kt

@@ -125,7 +125,7 @@ class EvaluateTestsTest {
 
     val error = res.errors[0]
     assertThat(error.message).isEqualTo("got an error")
-    assertThat(error.exception.message)
+    assertThat(error.exception().message)
       .isEqualTo(
         """
       –– Pkl Error ––
@@ -347,7 +347,7 @@ class EvaluateTestsTest {
     assertThat(fail1.message.stripFileAndLines(tempDir))
       .isEqualTo(
         """
-        #0 (/tempDir/example.pkl):
+        #0: (/tempDir/example.pkl)
           Expected: (/tempDir/example.pkl-expected.pcf)
           new {
             name = "Alice"

pkl-core/src/test/kotlin/org/pkl/core/runtime/AnsiCodingStringBuilderTest.kt

@@ -0,0 +1,76 @@
+/*
+ * Copyright © 2024 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.runtime
+
+import java.util.*
+import org.assertj.core.api.Assertions.assertThat
+import org.junit.jupiter.api.Test
+import org.pkl.core.runtime.AnsiCodingStringBuilder.AnsiCode
+
+class AnsiCodingStringBuilderTest {
+  @Test
+  fun `no formatting`() {
+    val result = AnsiCodingStringBuilder(false).append(AnsiCode.RED, "hello").toString()
+    assertThat(result).isEqualTo("hello")
+  }
+
+  private val red = "\u001b[31m"
+  private val redBold = "\u001b[1;31m"
+  private val reset = "\u001b[0m"
+  private val bold = "\u001b[1m"
+
+  // make test failures easier to debug
+  private val String.escaped
+    get() = replace("\u001b", "[ESC]")
+
+  @Test
+  fun `don't emit same color code`() {
+    val result =
+      AnsiCodingStringBuilder(true).append(AnsiCode.RED, "hi").append(AnsiCode.RED, "hi").toString()
+    assertThat(result.escaped).isEqualTo("${red}hihi${reset}".escaped)
+  }
+
+  @Test
+  fun `only add needed codes`() {
+    val result =
+      AnsiCodingStringBuilder(true)
+        .append(AnsiCode.RED, "hi")
+        .append(EnumSet.of(AnsiCode.RED, AnsiCode.BOLD), "hi")
+        .toString()
+    assertThat(result.escaped).isEqualTo("${red}hi${bold}hi${reset}".escaped)
+  }
+
+  @Test
+  fun `reset if need to subtract`() {
+    val result =
+      AnsiCodingStringBuilder(true)
+        .append(EnumSet.of(AnsiCode.RED, AnsiCode.BOLD), "hi")
+        .append(AnsiCode.RED, "hi")
+        .toString()
+    assertThat(result.escaped).isEqualTo("${redBold}hi${reset}${red}hi${reset}".escaped)
+  }
+
+  @Test
+  fun `plain text in between`() {
+    val result =
+      AnsiCodingStringBuilder(true)
+        .append(AnsiCode.RED, "hi")
+        .append("hi")
+        .append(AnsiCode.RED, "hi")
+        .toString()
+    assertThat(result.escaped).isEqualTo("${red}hi${reset}hi${red}hi${reset}".escaped)
+  }
+}

pkl-core/src/test/kotlin/org/pkl/core/runtime/StackTraceRendererTest.kt

@@ -190,7 +190,7 @@ class StackTraceRendererTest {
     }
     val loop = StackTraceRenderer.StackFrameLoop(loopFrames, 1)
     val frames = listOf(createFrame("bar", 1), createFrame("baz", 2), loop)
-    val formatter = TextFormatter.create(false)
+    val formatter = AnsiCodingStringBuilder(false)
     renderer.doRender(frames, null, formatter, "", true)
     val renderedFrames = formatter.toString()
     assertThat(renderedFrames)