From c83d049c7632dd4b48668baa7e952e61dfefe258 Mon Sep 17 00:00:00 2001
From: Robin Salkeld <salkeldr@amazon.com>
Date: Mon, 13 Feb 2023 14:50:10 -0800
Subject: [PATCH 01/18] =?UTF-8?q?First=20crack=20at=20=E2=80=9Clatest-nigh?=
 =?UTF-8?q?tly=E2=80=9D?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .github/workflows/main.yml |  2 +-
 index.js                   | 28 +++++++++++++++++++++++++++-
 test/setup-dafny-action.js |  8 ++++++++
 3 files changed, 36 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 320eb21..f1b6439 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -15,7 +15,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [macos-latest, ubuntu-latest, windows-latest]
-        dafny: [3.0.0, 3.7.3, 3.8.1, nightly-2022-09-23-2bc0042]
+        dafny: [3.0.0, 3.7.3, 3.8.1, nightly-2022-09-23-2bc0042, nightly-latest]
         # Windows 2.3.0 requires mono
         include:
           - os: macos-latest
diff --git a/index.js b/index.js
index e25eca7..2517c43 100644
--- a/index.js
+++ b/index.js
@@ -36,12 +36,38 @@ async function installDotnetTool(toolName, version) {
 exports.dafnyURL = dafnyURL;
 exports.getDistribution = getDistribution;
 
-function dafnyURL(version, distribution) {
+async function dafnyURL(version, distribution) {
   const versionPath = version.startsWith("nightly") ? "nightly" : `v${version}`;
+  if (version == "nightly-latest") {
+    version = await latestNightlyVersion()
+  }
   const root = "https://github.com/dafny-lang/dafny/releases/download";
   return `${root}/${versionPath}/dafny-${version == "2.3.0" ? "2.3.0.10506" : version}-x64-${distribution}.zip`;
 }
 
+async function latestNightlyVersion() {
+  // Shamelessly copied from dafny-lang/ide-vscode
+  // I'd prefer to use the GitHub API to list the assets under the "nightly" release,
+  // but @actions/github requires authentication.
+  // This method has the advantage of relying on more rigourous dotnet tool metadata at least.
+  const { stdout } = await execFileAsync("dotnet", [ 'tool', 'search', 'Dafny', '--detail', '--prerelease' ])
+  const entries = stdout.split('----------------').map(entry => entry.split('\n').filter(e => e !== ''))
+  const dafnyEntry = entries.filter(entry => entry[0] === 'dafny')[0]
+  const versionsIndex = dafnyEntry.findIndex(v => v.startsWith('Versions:'))
+  const versions = dafnyEntry.slice(versionsIndex + 1).map(versionLine => versionLine.trimStart().split(' ')[0])
+
+  const nightlies = versions.filter(l => l.includes('nightly'))
+  const dates = nightlies.map((n, index) => {
+    const split = n.split('-');
+    return { index, date: split[2] + split[3] + split[4] }
+  });
+  dates.sort((a, b) => a.date < b.date ? 1 : -1)
+  toolVersion = nightlies[dates[0].index]
+
+  core.info(`Using latest nightly version: ${toolVersion}`);
+  return toolVersion
+}
+
 function getDistribution(platform, version) {
   return platform === "darwin" // Osx
     ? version == "2.3.0" ? "osx-10.14.1" : "osx-10.14.2"
diff --git a/test/setup-dafny-action.js b/test/setup-dafny-action.js
index 2abe00d..0790b93 100644
--- a/test/setup-dafny-action.js
+++ b/test/setup-dafny-action.js
@@ -16,6 +16,14 @@ describe("dafnyURL", () => {
     );
   });
 
+  // TODO: Really we want to say "latest 3.x nightly" so that we don't automatically pick up major version bumps
+  it("latest nightly usage", () => {
+    const test = dafnyURL("latest-nightly", "ubuntu-16.04");
+    expect(test).to.match(
+      /^https:\/\/github.com\/dafny-lang\/dafny\/releases\/download\/nightly\/dafny-nightly-/
+    );
+  });
+
   it("version 2.3.0", () => {
     const test = dafnyURL("2.3.0", "win");
     // https://github.com/dafny-lang/dafny/releases/download/v2.3.0/dafny-2.3.0.10506-x64-osx-10.14.1.zip

From 7fff98609007d8ad3e88777d9d3f142b83e9b5a7 Mon Sep 17 00:00:00 2001
From: Robin Salkeld <salkeldr@amazon.com>
Date: Mon, 13 Feb 2023 15:04:42 -0800
Subject: [PATCH 02/18] Fixes (turns out running npm test first helps :)

---
 .github/workflows/main.yml |  2 +-
 index.js                   |  2 +-
 test/setup-dafny-action.js | 18 +++++++++---------
 3 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index f1b6439..5799018 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -15,7 +15,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [macos-latest, ubuntu-latest, windows-latest]
-        dafny: [3.0.0, 3.7.3, 3.8.1, nightly-2022-09-23-2bc0042, nightly-latest]
+        dafny: [3.0.0, 3.7.3, 3.8.1, nightly-2023-02-13-14bc57f, nightly-latest]
         # Windows 2.3.0 requires mono
         include:
           - os: macos-latest
diff --git a/index.js b/index.js
index 2517c43..a527e9d 100644
--- a/index.js
+++ b/index.js
@@ -50,7 +50,7 @@ async function latestNightlyVersion() {
   // I'd prefer to use the GitHub API to list the assets under the "nightly" release,
   // but @actions/github requires authentication.
   // This method has the advantage of relying on more rigourous dotnet tool metadata at least.
-  const { stdout } = await execFileAsync("dotnet", [ 'tool', 'search', 'Dafny', '--detail', '--prerelease' ])
+  const { exitCode, stdout, stderr } = await exec.getExecOutput("dotnet", [ 'tool', 'search', 'Dafny', '--detail', '--prerelease' ], {silent: true})
   const entries = stdout.split('----------------').map(entry => entry.split('\n').filter(e => e !== ''))
   const dafnyEntry = entries.filter(entry => entry[0] === 'dafny')[0]
   const versionsIndex = dafnyEntry.findIndex(v => v.startsWith('Versions:'))
diff --git a/test/setup-dafny-action.js b/test/setup-dafny-action.js
index 0790b93..9073c96 100644
--- a/test/setup-dafny-action.js
+++ b/test/setup-dafny-action.js
@@ -2,30 +2,30 @@ const { dafnyURL, getDistribution } = require("../index");
 const { expect } = require("chai");
 
 describe("dafnyURL", () => {
-  it("basic usage", () => {
-    const test = dafnyURL("3.8.1", "win");
+  it("basic usage", async () => {
+    const test = await dafnyURL("3.8.1", "win");
     expect(test).to.equal(
       "https://github.com/dafny-lang/dafny/releases/download/v3.8.1/dafny-3.8.1-x64-win.zip"
     );
   });
 
-  it("nightly usage", () => {
-    const test = dafnyURL("nightly-2022-09-23-2bc0042", "ubuntu-16.04");
+  it("nightly usage", async () => {
+    const test = await dafnyURL("nightly-2022-09-23-2bc0042", "ubuntu-16.04");
     expect(test).to.equal(
       "https://github.com/dafny-lang/dafny/releases/download/nightly/dafny-nightly-2022-09-23-2bc0042-x64-ubuntu-16.04.zip"
     );
   });
 
   // TODO: Really we want to say "latest 3.x nightly" so that we don't automatically pick up major version bumps
-  it("latest nightly usage", () => {
-    const test = dafnyURL("latest-nightly", "ubuntu-16.04");
+  it("latest nightly usage", async () => {
+    const test = await dafnyURL("nightly-latest", "ubuntu-16.04");
     expect(test).to.match(
-      /^https:\/\/github.com\/dafny-lang\/dafny\/releases\/download\/nightly\/dafny-nightly-/
+      /^https:\/\/github.com\/dafny-lang\/dafny\/releases\/download\/nightly\/dafny-.*-nightly-/
     );
   });
 
-  it("version 2.3.0", () => {
-    const test = dafnyURL("2.3.0", "win");
+  it("version 2.3.0", async () => {
+    const test = await dafnyURL("2.3.0", "win");
     // https://github.com/dafny-lang/dafny/releases/download/v2.3.0/dafny-2.3.0.10506-x64-osx-10.14.1.zip
     // https://github.com/dafny-lang/dafny/releases/download/v2.3.0/dafny-2.3.0.10506-x64-ubuntu-16.04.zip
     // https://github.com/dafny-lang/dafny/releases/download/v2.3.0/dafny-2.3.0.10506-x64-win.zip

From eabad98afc5d430c661ebd72a1bb649dc222e9ca Mon Sep 17 00:00:00 2001
From: Robin Salkeld <salkeldr@amazon.com>
Date: Mon, 13 Feb 2023 15:08:31 -0800
Subject: [PATCH 03/18] So does npm run package

---
 dist/index.js | 28 +++++++++++++++++++++++++++-
 1 file changed, 27 insertions(+), 1 deletion(-)

diff --git a/dist/index.js b/dist/index.js
index 031e57a..fbd3004 100644
--- a/dist/index.js
+++ b/dist/index.js
@@ -6724,12 +6724,38 @@ async function installDotnetTool(toolName, version) {
 exports.dafnyURL = dafnyURL;
 exports.getDistribution = getDistribution;
 
-function dafnyURL(version, distribution) {
+async function dafnyURL(version, distribution) {
   const versionPath = version.startsWith("nightly") ? "nightly" : `v${version}`;
+  if (version == "nightly-latest") {
+    version = await latestNightlyVersion()
+  }
   const root = "https://github.com/dafny-lang/dafny/releases/download";
   return `${root}/${versionPath}/dafny-${version == "2.3.0" ? "2.3.0.10506" : version}-x64-${distribution}.zip`;
 }
 
+async function latestNightlyVersion() {
+  // Shamelessly copied from dafny-lang/ide-vscode
+  // I'd prefer to use the GitHub API to list the assets under the "nightly" release,
+  // but @actions/github requires authentication.
+  // This method has the advantage of relying on more rigourous dotnet tool metadata at least.
+  const { exitCode, stdout, stderr } = await exec.getExecOutput("dotnet", [ 'tool', 'search', 'Dafny', '--detail', '--prerelease' ], {silent: true})
+  const entries = stdout.split('----------------').map(entry => entry.split('\n').filter(e => e !== ''))
+  const dafnyEntry = entries.filter(entry => entry[0] === 'dafny')[0]
+  const versionsIndex = dafnyEntry.findIndex(v => v.startsWith('Versions:'))
+  const versions = dafnyEntry.slice(versionsIndex + 1).map(versionLine => versionLine.trimStart().split(' ')[0])
+
+  const nightlies = versions.filter(l => l.includes('nightly'))
+  const dates = nightlies.map((n, index) => {
+    const split = n.split('-');
+    return { index, date: split[2] + split[3] + split[4] }
+  });
+  dates.sort((a, b) => a.date < b.date ? 1 : -1)
+  toolVersion = nightlies[dates[0].index]
+
+  core.info(`Using latest nightly version: ${toolVersion}`);
+  return toolVersion
+}
+
 function getDistribution(platform, version) {
   return platform === "darwin" // Osx
     ? version == "2.3.0" ? "osx-10.14.1" : "osx-10.14.2"

From 98646ae8a0d33de3b3df13645c00a85bb18a4123 Mon Sep 17 00:00:00 2001
From: Robin Salkeld <salkeldr@amazon.com>
Date: Mon, 13 Feb 2023 15:14:24 -0800
Subject: [PATCH 04/18] Formatting, missing await

---
 index.js | 58 +++++++++++++++++++++++++++++++++++++++-----------------
 1 file changed, 41 insertions(+), 17 deletions(-)

diff --git a/index.js b/index.js
index a527e9d..fa7b5f7 100644
--- a/index.js
+++ b/index.js
@@ -7,7 +7,7 @@ const os = require("os");
   try {
     const version = core.getInput("dafny-version", { required: true });
     const distribution = getDistribution(os.platform(), version);
-    const url = dafnyURL(version, distribution);
+    const url = await dafnyURL(version, distribution);
 
     core.info(`Dafny Url: ${url}`);
     core.info(`Dafny Distribution: ${distribution}`);
@@ -22,14 +22,21 @@ const os = require("os");
     // Install related tools.
     // Hopefully in the future we can install Dafny itself this way as well.
     // For now the zipped releases are simpler because they include Z3.
-    await installDotnetTool("dafny-reportgenerator", "1.*")
+    await installDotnetTool("dafny-reportgenerator", "1.*");
   } catch (error) {
     core.setFailed(error.message);
   }
 })();
 
 async function installDotnetTool(toolName, version) {
-  await exec.exec("dotnet", ["tool", "install", "-g", toolName, "--version", version])
+  await exec.exec("dotnet", [
+    "tool",
+    "install",
+    "-g",
+    toolName,
+    "--version",
+    version,
+  ]);
 }
 
 // Export functions for testing
@@ -39,10 +46,12 @@ exports.getDistribution = getDistribution;
 async function dafnyURL(version, distribution) {
   const versionPath = version.startsWith("nightly") ? "nightly" : `v${version}`;
   if (version == "nightly-latest") {
-    version = await latestNightlyVersion()
+    version = await latestNightlyVersion();
   }
   const root = "https://github.com/dafny-lang/dafny/releases/download";
-  return `${root}/${versionPath}/dafny-${version == "2.3.0" ? "2.3.0.10506" : version}-x64-${distribution}.zip`;
+  return `${root}/${versionPath}/dafny-${
+    version == "2.3.0" ? "2.3.0.10506" : version
+  }-x64-${distribution}.zip`;
 }
 
 async function latestNightlyVersion() {
@@ -50,27 +59,42 @@ async function latestNightlyVersion() {
   // I'd prefer to use the GitHub API to list the assets under the "nightly" release,
   // but @actions/github requires authentication.
   // This method has the advantage of relying on more rigourous dotnet tool metadata at least.
-  const { exitCode, stdout, stderr } = await exec.getExecOutput("dotnet", [ 'tool', 'search', 'Dafny', '--detail', '--prerelease' ], {silent: true})
-  const entries = stdout.split('----------------').map(entry => entry.split('\n').filter(e => e !== ''))
-  const dafnyEntry = entries.filter(entry => entry[0] === 'dafny')[0]
-  const versionsIndex = dafnyEntry.findIndex(v => v.startsWith('Versions:'))
-  const versions = dafnyEntry.slice(versionsIndex + 1).map(versionLine => versionLine.trimStart().split(' ')[0])
+  const { exitCode, stdout, stderr } = await exec.getExecOutput(
+    "dotnet",
+    ["tool", "search", "Dafny", "--detail", "--prerelease"],
+    { silent: true }
+  );
+  if (exitCode != 0) {
+    throw new Error(
+      `dotnet tool command failed (exitCode ${exitCode}):\n${stderr}"`
+    );
+  }
+  const entries = stdout
+    .split("----------------")
+    .map((entry) => entry.split("\n").filter((e) => e !== ""));
+  const dafnyEntry = entries.filter((entry) => entry[0] === "dafny")[0];
+  const versionsIndex = dafnyEntry.findIndex((v) => v.startsWith("Versions:"));
+  const versions = dafnyEntry
+    .slice(versionsIndex + 1)
+    .map((versionLine) => versionLine.trimStart().split(" ")[0]);
 
-  const nightlies = versions.filter(l => l.includes('nightly'))
+  const nightlies = versions.filter((l) => l.includes("nightly"));
   const dates = nightlies.map((n, index) => {
-    const split = n.split('-');
-    return { index, date: split[2] + split[3] + split[4] }
+    const split = n.split("-");
+    return { index, date: split[2] + split[3] + split[4] };
   });
-  dates.sort((a, b) => a.date < b.date ? 1 : -1)
-  toolVersion = nightlies[dates[0].index]
+  dates.sort((a, b) => (a.date < b.date ? 1 : -1));
+  const toolVersion = nightlies[dates[0].index];
 
   core.info(`Using latest nightly version: ${toolVersion}`);
-  return toolVersion
+  return toolVersion;
 }
 
 function getDistribution(platform, version) {
   return platform === "darwin" // Osx
-    ? version == "2.3.0" ? "osx-10.14.1" : "osx-10.14.2"
+    ? version == "2.3.0"
+      ? "osx-10.14.1"
+      : "osx-10.14.2"
     : platform === "win32" // windows
     ? "win"
     : "ubuntu-16.04"; // Everything else is linux...

From 38856bde99cdd4e2e79d5ab6846814e7850218ee Mon Sep 17 00:00:00 2001
From: Robin Salkeld <salkeldr@amazon.com>
Date: Mon, 13 Feb 2023 15:15:51 -0800
Subject: [PATCH 05/18] Package

---
 dist/index.js | 60 +++++++++++++++++++++++++++++++++++----------------
 1 file changed, 42 insertions(+), 18 deletions(-)

diff --git a/dist/index.js b/dist/index.js
index fbd3004..c1a8388 100644
--- a/dist/index.js
+++ b/dist/index.js
@@ -6695,7 +6695,7 @@ const os = __nccwpck_require__(2037);
   try {
     const version = core.getInput("dafny-version", { required: true });
     const distribution = getDistribution(os.platform(), version);
-    const url = dafnyURL(version, distribution);
+    const url = await dafnyURL(version, distribution);
 
     core.info(`Dafny Url: ${url}`);
     core.info(`Dafny Distribution: ${distribution}`);
@@ -6710,14 +6710,21 @@ const os = __nccwpck_require__(2037);
     // Install related tools.
     // Hopefully in the future we can install Dafny itself this way as well.
     // For now the zipped releases are simpler because they include Z3.
-    await installDotnetTool("dafny-reportgenerator", "1.*")
+    await installDotnetTool("dafny-reportgenerator", "1.*");
   } catch (error) {
     core.setFailed(error.message);
   }
 })();
 
 async function installDotnetTool(toolName, version) {
-  await exec.exec("dotnet", ["tool", "install", "-g", toolName, "--version", version])
+  await exec.exec("dotnet", [
+    "tool",
+    "install",
+    "-g",
+    toolName,
+    "--version",
+    version,
+  ]);
 }
 
 // Export functions for testing
@@ -6727,10 +6734,12 @@ exports.getDistribution = getDistribution;
 async function dafnyURL(version, distribution) {
   const versionPath = version.startsWith("nightly") ? "nightly" : `v${version}`;
   if (version == "nightly-latest") {
-    version = await latestNightlyVersion()
+    version = await latestNightlyVersion();
   }
   const root = "https://github.com/dafny-lang/dafny/releases/download";
-  return `${root}/${versionPath}/dafny-${version == "2.3.0" ? "2.3.0.10506" : version}-x64-${distribution}.zip`;
+  return `${root}/${versionPath}/dafny-${
+    version == "2.3.0" ? "2.3.0.10506" : version
+  }-x64-${distribution}.zip`;
 }
 
 async function latestNightlyVersion() {
@@ -6738,27 +6747,42 @@ async function latestNightlyVersion() {
   // I'd prefer to use the GitHub API to list the assets under the "nightly" release,
   // but @actions/github requires authentication.
   // This method has the advantage of relying on more rigourous dotnet tool metadata at least.
-  const { exitCode, stdout, stderr } = await exec.getExecOutput("dotnet", [ 'tool', 'search', 'Dafny', '--detail', '--prerelease' ], {silent: true})
-  const entries = stdout.split('----------------').map(entry => entry.split('\n').filter(e => e !== ''))
-  const dafnyEntry = entries.filter(entry => entry[0] === 'dafny')[0]
-  const versionsIndex = dafnyEntry.findIndex(v => v.startsWith('Versions:'))
-  const versions = dafnyEntry.slice(versionsIndex + 1).map(versionLine => versionLine.trimStart().split(' ')[0])
-
-  const nightlies = versions.filter(l => l.includes('nightly'))
+  const { exitCode, stdout, stderr } = await exec.getExecOutput(
+    "dotnet",
+    ["tool", "search", "Dafny", "--detail", "--prerelease"],
+    { silent: true }
+  );
+  if (exitCode != 0) {
+    throw new Error(
+      `dotnet tool command failed (exitCode ${exitCode}):\n${stderr}"`
+    );
+  }
+  const entries = stdout
+    .split("----------------")
+    .map((entry) => entry.split("\n").filter((e) => e !== ""));
+  const dafnyEntry = entries.filter((entry) => entry[0] === "dafny")[0];
+  const versionsIndex = dafnyEntry.findIndex((v) => v.startsWith("Versions:"));
+  const versions = dafnyEntry
+    .slice(versionsIndex + 1)
+    .map((versionLine) => versionLine.trimStart().split(" ")[0]);
+
+  const nightlies = versions.filter((l) => l.includes("nightly"));
   const dates = nightlies.map((n, index) => {
-    const split = n.split('-');
-    return { index, date: split[2] + split[3] + split[4] }
+    const split = n.split("-");
+    return { index, date: split[2] + split[3] + split[4] };
   });
-  dates.sort((a, b) => a.date < b.date ? 1 : -1)
-  toolVersion = nightlies[dates[0].index]
+  dates.sort((a, b) => (a.date < b.date ? 1 : -1));
+  const toolVersion = nightlies[dates[0].index];
 
   core.info(`Using latest nightly version: ${toolVersion}`);
-  return toolVersion
+  return toolVersion;
 }
 
 function getDistribution(platform, version) {
   return platform === "darwin" // Osx
-    ? version == "2.3.0" ? "osx-10.14.1" : "osx-10.14.2"
+    ? version == "2.3.0"
+      ? "osx-10.14.1"
+      : "osx-10.14.2"
     : platform === "win32" // windows
     ? "win"
     : "ubuntu-16.04"; // Everything else is linux...

From 09245dd4909f7438e2b812108194952453d9aea8 Mon Sep 17 00:00:00 2001
From: Robin Salkeld <salkeldr@amazon.com>
Date: Mon, 13 Feb 2023 15:29:08 -0800
Subject: [PATCH 06/18] Trim off version prefix

---
 dist/index.js              | 12 ++++++------
 index.js                   |  8 ++++----
 test/setup-dafny-action.js |  2 +-
 3 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/dist/index.js b/dist/index.js
index c1a8388..f1e4b48 100644
--- a/dist/index.js
+++ b/dist/index.js
@@ -6743,10 +6743,9 @@ async function dafnyURL(version, distribution) {
 }
 
 async function latestNightlyVersion() {
-  // Shamelessly copied from dafny-lang/ide-vscode
+  // Shamelessly copied and modified from dafny-lang/ide-vscode
   // I'd prefer to use the GitHub API to list the assets under the "nightly" release,
   // but @actions/github requires authentication.
-  // This method has the advantage of relying on more rigourous dotnet tool metadata at least.
   const { exitCode, stdout, stderr } = await exec.getExecOutput(
     "dotnet",
     ["tool", "search", "Dafny", "--detail", "--prerelease"],
@@ -6773,9 +6772,10 @@ async function latestNightlyVersion() {
   });
   dates.sort((a, b) => (a.date < b.date ? 1 : -1));
   const toolVersion = nightlies[dates[0].index];
+  const version = toolVersion.slice(toolVersion.indexOf("-") + 1)
 
-  core.info(`Using latest nightly version: ${toolVersion}`);
-  return toolVersion;
+  core.info(`Using latest nightly version: ${version}`);
+  return version;
 }
 
 function getDistribution(platform, version) {
@@ -6784,8 +6784,8 @@ function getDistribution(platform, version) {
       ? "osx-10.14.1"
       : "osx-10.14.2"
     : platform === "win32" // windows
-    ? "win"
-    : "ubuntu-16.04"; // Everything else is linux...
+      ? "win"
+      : "ubuntu-16.04"; // Everything else is linux...
 }
 
 })();
diff --git a/index.js b/index.js
index fa7b5f7..baac89f 100644
--- a/index.js
+++ b/index.js
@@ -55,10 +55,9 @@ async function dafnyURL(version, distribution) {
 }
 
 async function latestNightlyVersion() {
-  // Shamelessly copied from dafny-lang/ide-vscode
+  // Shamelessly copied and modified from dafny-lang/ide-vscode
   // I'd prefer to use the GitHub API to list the assets under the "nightly" release,
   // but @actions/github requires authentication.
-  // This method has the advantage of relying on more rigourous dotnet tool metadata at least.
   const { exitCode, stdout, stderr } = await exec.getExecOutput(
     "dotnet",
     ["tool", "search", "Dafny", "--detail", "--prerelease"],
@@ -85,9 +84,10 @@ async function latestNightlyVersion() {
   });
   dates.sort((a, b) => (a.date < b.date ? 1 : -1));
   const toolVersion = nightlies[dates[0].index];
+  const version = toolVersion.slice(toolVersion.indexOf("-") + 1);
 
-  core.info(`Using latest nightly version: ${toolVersion}`);
-  return toolVersion;
+  core.info(`Using latest nightly version: ${version}`);
+  return version;
 }
 
 function getDistribution(platform, version) {
diff --git a/test/setup-dafny-action.js b/test/setup-dafny-action.js
index 9073c96..6a48083 100644
--- a/test/setup-dafny-action.js
+++ b/test/setup-dafny-action.js
@@ -20,7 +20,7 @@ describe("dafnyURL", () => {
   it("latest nightly usage", async () => {
     const test = await dafnyURL("nightly-latest", "ubuntu-16.04");
     expect(test).to.match(
-      /^https:\/\/github.com\/dafny-lang\/dafny\/releases\/download\/nightly\/dafny-.*-nightly-/
+      /^https:\/\/github.com\/dafny-lang\/dafny\/releases\/download\/nightly\/dafny-nightly-/
     );
   });
 

From d94ed1f64d89b1a015597977487f33f2448a60d9 Mon Sep 17 00:00:00 2001
From: Robin Salkeld <salkeldr@amazon.com>
Date: Mon, 13 Feb 2023 15:37:15 -0800
Subject: [PATCH 07/18] Case-insensitive grep in test script

---
 __tests__/verify-dafny.sh | 2 +-
 dist/index.js             | 8 +++++---
 index.js                  | 2 ++
 3 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/__tests__/verify-dafny.sh b/__tests__/verify-dafny.sh
index 76e95f6..78db7f0 100755
--- a/__tests__/verify-dafny.sh
+++ b/__tests__/verify-dafny.sh
@@ -26,7 +26,7 @@ fi
 echo "Expected Dafny Version: $expectedVersionString"
 dafny_version="$(dafny $version)"
 echo "Found $dafny_version"
-if ! echo "$dafny_version" | grep -q "Dafny $expectedVersionString"; then
+if ! echo "$dafny_version" | grep -qi "Dafny $expectedVersionString"; then
   echo "Unexpected version" 1>&2
   exit 1
 fi
diff --git a/dist/index.js b/dist/index.js
index f1e4b48..1d8d0db 100644
--- a/dist/index.js
+++ b/dist/index.js
@@ -6772,7 +6772,9 @@ async function latestNightlyVersion() {
   });
   dates.sort((a, b) => (a.date < b.date ? 1 : -1));
   const toolVersion = nightlies[dates[0].index];
-  const version = toolVersion.slice(toolVersion.indexOf("-") + 1)
+
+  // Slice off the "3.11.0.50201-" from 3.11.0.50201-nightly-2023-02-13-14bc57f, for e.g.
+  const version = toolVersion.slice(toolVersion.indexOf("-") + 1);
 
   core.info(`Using latest nightly version: ${version}`);
   return version;
@@ -6784,8 +6786,8 @@ function getDistribution(platform, version) {
       ? "osx-10.14.1"
       : "osx-10.14.2"
     : platform === "win32" // windows
-      ? "win"
-      : "ubuntu-16.04"; // Everything else is linux...
+    ? "win"
+    : "ubuntu-16.04"; // Everything else is linux...
 }
 
 })();
diff --git a/index.js b/index.js
index baac89f..dc2a9a7 100644
--- a/index.js
+++ b/index.js
@@ -84,6 +84,8 @@ async function latestNightlyVersion() {
   });
   dates.sort((a, b) => (a.date < b.date ? 1 : -1));
   const toolVersion = nightlies[dates[0].index];
+
+  // Slice off the "3.11.0.50201-" from 3.11.0.50201-nightly-2023-02-13-14bc57f, for e.g.
   const version = toolVersion.slice(toolVersion.indexOf("-") + 1);
 
   core.info(`Using latest nightly version: ${version}`);

From 3b8354c907235b0f9f327e8abea31b97e39236a3 Mon Sep 17 00:00:00 2001
From: Robin Salkeld <salkeldr@amazon.com>
Date: Tue, 14 Feb 2023 10:30:02 -0800
Subject: [PATCH 08/18] Debugging windows failure

---
 dist/index.js | 5 ++---
 index.js      | 5 ++---
 2 files changed, 4 insertions(+), 6 deletions(-)

diff --git a/dist/index.js b/dist/index.js
index 1d8d0db..9dda30d 100644
--- a/dist/index.js
+++ b/dist/index.js
@@ -6743,9 +6743,7 @@ async function dafnyURL(version, distribution) {
 }
 
 async function latestNightlyVersion() {
-  // Shamelessly copied and modified from dafny-lang/ide-vscode
-  // I'd prefer to use the GitHub API to list the assets under the "nightly" release,
-  // but @actions/github requires authentication.
+  // Shamelessly copied and modified from dafny-lang/ide-vscode.
   const { exitCode, stdout, stderr } = await exec.getExecOutput(
     "dotnet",
     ["tool", "search", "Dafny", "--detail", "--prerelease"],
@@ -6756,6 +6754,7 @@ async function latestNightlyVersion() {
       `dotnet tool command failed (exitCode ${exitCode}):\n${stderr}"`
     );
   }
+  await console.log(stdout)
   const entries = stdout
     .split("----------------")
     .map((entry) => entry.split("\n").filter((e) => e !== ""));
diff --git a/index.js b/index.js
index dc2a9a7..e5b35cf 100644
--- a/index.js
+++ b/index.js
@@ -55,9 +55,7 @@ async function dafnyURL(version, distribution) {
 }
 
 async function latestNightlyVersion() {
-  // Shamelessly copied and modified from dafny-lang/ide-vscode
-  // I'd prefer to use the GitHub API to list the assets under the "nightly" release,
-  // but @actions/github requires authentication.
+  // Shamelessly copied and modified from dafny-lang/ide-vscode.
   const { exitCode, stdout, stderr } = await exec.getExecOutput(
     "dotnet",
     ["tool", "search", "Dafny", "--detail", "--prerelease"],
@@ -68,6 +66,7 @@ async function latestNightlyVersion() {
       `dotnet tool command failed (exitCode ${exitCode}):\n${stderr}"`
     );
   }
+  await console.log(stdout)
   const entries = stdout
     .split("----------------")
     .map((entry) => entry.split("\n").filter((e) => e !== ""));

From 63517f13f0b6f073de82712336d737ce48373f51 Mon Sep 17 00:00:00 2001
From: Robin Salkeld <salkeldr@amazon.com>
Date: Tue, 14 Feb 2023 11:25:04 -0800
Subject: [PATCH 09/18] More debugging windows

---
 .github/workflows/main.yml | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 5799018..e5da048 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -23,6 +23,8 @@ jobs:
           - os: ubuntu-latest
             dafny: 2.3.0
     steps:
+      - run: dotnet tool search --help
+
       - name: Checkout
         uses: actions/checkout@v2
 

From 1336a5329532fda33a2305c9c2cc1beec4b6dba2 Mon Sep 17 00:00:00 2001
From: Robin Salkeld <salkeldr@amazon.com>
Date: Tue, 14 Feb 2023 11:29:35 -0800
Subject: [PATCH 10/18] More debugging

---
 index.js | 1 +
 1 file changed, 1 insertion(+)

diff --git a/index.js b/index.js
index e5b35cf..cdfccf8 100644
--- a/index.js
+++ b/index.js
@@ -70,6 +70,7 @@ async function latestNightlyVersion() {
   const entries = stdout
     .split("----------------")
     .map((entry) => entry.split("\n").filter((e) => e !== ""));
+  await console.log(entries)
   const dafnyEntry = entries.filter((entry) => entry[0] === "dafny")[0];
   const versionsIndex = dafnyEntry.findIndex((v) => v.startsWith("Versions:"));
   const versions = dafnyEntry

From 4a5e8c9b6c69ec5c524371632f515f342ee576c3 Mon Sep 17 00:00:00 2001
From: Robin Salkeld <salkeldr@amazon.com>
Date: Tue, 14 Feb 2023 11:31:39 -0800
Subject: [PATCH 11/18] Package

---
 dist/index.js | 1 +
 1 file changed, 1 insertion(+)

diff --git a/dist/index.js b/dist/index.js
index 9dda30d..96ff0a4 100644
--- a/dist/index.js
+++ b/dist/index.js
@@ -6758,6 +6758,7 @@ async function latestNightlyVersion() {
   const entries = stdout
     .split("----------------")
     .map((entry) => entry.split("\n").filter((e) => e !== ""));
+  await console.log(entries)
   const dafnyEntry = entries.filter((entry) => entry[0] === "dafny")[0];
   const versionsIndex = dafnyEntry.findIndex((v) => v.startsWith("Versions:"));
   const versions = dafnyEntry

From a2efa0548a1d0d55f4620258308a4dea024e0b7e Mon Sep 17 00:00:00 2001
From: Robin Salkeld <salkeldr@amazon.com>
Date: Tue, 14 Feb 2023 11:36:00 -0800
Subject: [PATCH 12/18] Fix windows

---
 dist/index.js | 4 +---
 index.js      | 4 +---
 2 files changed, 2 insertions(+), 6 deletions(-)

diff --git a/dist/index.js b/dist/index.js
index 96ff0a4..6ca475f 100644
--- a/dist/index.js
+++ b/dist/index.js
@@ -6754,11 +6754,9 @@ async function latestNightlyVersion() {
       `dotnet tool command failed (exitCode ${exitCode}):\n${stderr}"`
     );
   }
-  await console.log(stdout)
   const entries = stdout
     .split("----------------")
-    .map((entry) => entry.split("\n").filter((e) => e !== ""));
-  await console.log(entries)
+    .map((entry) => entry.split("\r?\n").filter((e) => e !== ""));
   const dafnyEntry = entries.filter((entry) => entry[0] === "dafny")[0];
   const versionsIndex = dafnyEntry.findIndex((v) => v.startsWith("Versions:"));
   const versions = dafnyEntry
diff --git a/index.js b/index.js
index cdfccf8..ddb267a 100644
--- a/index.js
+++ b/index.js
@@ -66,11 +66,9 @@ async function latestNightlyVersion() {
       `dotnet tool command failed (exitCode ${exitCode}):\n${stderr}"`
     );
   }
-  await console.log(stdout)
   const entries = stdout
     .split("----------------")
-    .map((entry) => entry.split("\n").filter((e) => e !== ""));
-  await console.log(entries)
+    .map((entry) => entry.split("\r?\n").filter((e) => e !== ""));
   const dafnyEntry = entries.filter((entry) => entry[0] === "dafny")[0];
   const versionsIndex = dafnyEntry.findIndex((v) => v.startsWith("Versions:"));
   const versions = dafnyEntry

From 562807d061b1fd80541c2cba9e51699a825ea6de Mon Sep 17 00:00:00 2001
From: Robin Salkeld <salkeldr@amazon.com>
Date: Tue, 14 Feb 2023 11:38:56 -0800
Subject: [PATCH 13/18] Typo and big old comment

---
 dist/index.js | 9 ++++++++-
 index.js      | 9 ++++++++-
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/dist/index.js b/dist/index.js
index 6ca475f..7c48e21 100644
--- a/dist/index.js
+++ b/dist/index.js
@@ -6744,6 +6744,13 @@ async function dafnyURL(version, distribution) {
 
 async function latestNightlyVersion() {
   // Shamelessly copied and modified from dafny-lang/ide-vscode.
+  // Parsing the dotnet tool output is obviously not great,
+  // and we could consider using the NuGet API in the future.
+  // Alternatively if we move to installing Dafny using `dotnet tool install`
+  // we could use the `--prerelease` flag, although that assumes
+  // that all nightly builds use a fresh version number,
+  // and can't be used together with `--version` to express something like
+  // "install the latest 3.X version including prereleases".
   const { exitCode, stdout, stderr } = await exec.getExecOutput(
     "dotnet",
     ["tool", "search", "Dafny", "--detail", "--prerelease"],
@@ -6756,7 +6763,7 @@ async function latestNightlyVersion() {
   }
   const entries = stdout
     .split("----------------")
-    .map((entry) => entry.split("\r?\n").filter((e) => e !== ""));
+    .map((entry) => entry.split(/\r?\n/).filter((e) => e !== ""));
   const dafnyEntry = entries.filter((entry) => entry[0] === "dafny")[0];
   const versionsIndex = dafnyEntry.findIndex((v) => v.startsWith("Versions:"));
   const versions = dafnyEntry
diff --git a/index.js b/index.js
index ddb267a..303a7b6 100644
--- a/index.js
+++ b/index.js
@@ -56,6 +56,13 @@ async function dafnyURL(version, distribution) {
 
 async function latestNightlyVersion() {
   // Shamelessly copied and modified from dafny-lang/ide-vscode.
+  // Parsing the dotnet tool output is obviously not great,
+  // and we could consider using the NuGet API in the future.
+  // Alternatively if we move to installing Dafny using `dotnet tool install`
+  // we could use the `--prerelease` flag, although that assumes
+  // that all nightly builds use a fresh version number,
+  // and can't be used together with `--version` to express something like
+  // "install the latest 3.X version including prereleases".
   const { exitCode, stdout, stderr } = await exec.getExecOutput(
     "dotnet",
     ["tool", "search", "Dafny", "--detail", "--prerelease"],
@@ -68,7 +75,7 @@ async function latestNightlyVersion() {
   }
   const entries = stdout
     .split("----------------")
-    .map((entry) => entry.split("\r?\n").filter((e) => e !== ""));
+    .map((entry) => entry.split(/\r?\n/).filter((e) => e !== ""));
   const dafnyEntry = entries.filter((entry) => entry[0] === "dafny")[0];
   const versionsIndex = dafnyEntry.findIndex((v) => v.startsWith("Versions:"));
   const versions = dafnyEntry

From 51ed729d8fdbb3454a4327c1d7b6c3d39ef33531 Mon Sep 17 00:00:00 2001
From: Robin Salkeld <salkeldr@amazon.com>
Date: Tue, 14 Feb 2023 11:47:49 -0800
Subject: [PATCH 14/18] Comments

---
 .github/workflows/main.yml | 4 ++++
 test/setup-dafny-action.js | 3 +--
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index e5da048..04f4fcf 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -23,6 +23,10 @@ jobs:
           - os: ubuntu-latest
             dafny: 2.3.0
     steps:
+      # The first call to `dotnet tool` on a fresh runner sometimes takes multiple minutes,
+      # perhaps because it is lazily downloading and installing assets.
+      # It helps to hit that here so we don't hit it in a mocha test with a tight timeout.
+      - name: Warm up dotnet tool
       - run: dotnet tool search --help
 
       - name: Checkout
diff --git a/test/setup-dafny-action.js b/test/setup-dafny-action.js
index 6a48083..45c0027 100644
--- a/test/setup-dafny-action.js
+++ b/test/setup-dafny-action.js
@@ -16,13 +16,12 @@ describe("dafnyURL", () => {
     );
   });
 
-  // TODO: Really we want to say "latest 3.x nightly" so that we don't automatically pick up major version bumps
   it("latest nightly usage", async () => {
     const test = await dafnyURL("nightly-latest", "ubuntu-16.04");
     expect(test).to.match(
       /^https:\/\/github.com\/dafny-lang\/dafny\/releases\/download\/nightly\/dafny-nightly-/
     );
-  });
+  }).timeout(5000); // Invoking and parsing the output of `dotnet tool search` can take a bit over 2 seconds
 
   it("version 2.3.0", async () => {
     const test = await dafnyURL("2.3.0", "win");

From 8b30437bafc4523e3385d3c7f25598aeb7aea44d Mon Sep 17 00:00:00 2001
From: Robin Salkeld <salkeldr@amazon.com>
Date: Tue, 14 Feb 2023 11:54:25 -0800
Subject: [PATCH 15/18] Poke CI


From 8a5d5cc537a20bc68cbb66acd0b18c882e4297a1 Mon Sep 17 00:00:00 2001
From: Robin Salkeld <salkeldr@amazon.com>
Date: Tue, 14 Feb 2023 12:50:29 -0800
Subject: [PATCH 16/18] Workflow typo

---
 .github/workflows/main.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 04f4fcf..aa46cc2 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -27,7 +27,7 @@ jobs:
       # perhaps because it is lazily downloading and installing assets.
       # It helps to hit that here so we don't hit it in a mocha test with a tight timeout.
       - name: Warm up dotnet tool
-      - run: dotnet tool search --help
+        run: dotnet tool search --help
 
       - name: Checkout
         uses: actions/checkout@v2

From 5d5649ba111832dbb1d27be0d1076d1f681ebf0c Mon Sep 17 00:00:00 2001
From: Robin Salkeld <salkeldr@amazon.com>
Date: Tue, 14 Feb 2023 13:40:04 -0800
Subject: [PATCH 17/18] Increase test timeout

---
 test/setup-dafny-action.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/test/setup-dafny-action.js b/test/setup-dafny-action.js
index 45c0027..da61dd0 100644
--- a/test/setup-dafny-action.js
+++ b/test/setup-dafny-action.js
@@ -21,7 +21,7 @@ describe("dafnyURL", () => {
     expect(test).to.match(
       /^https:\/\/github.com\/dafny-lang\/dafny\/releases\/download\/nightly\/dafny-nightly-/
     );
-  }).timeout(5000); // Invoking and parsing the output of `dotnet tool search` can take a bit over 2 seconds
+  }).timeout(20_000); // Invoking and parsing the output of `dotnet tool search` can take well over 2 seconds
 
   it("version 2.3.0", async () => {
     const test = await dafnyURL("2.3.0", "win");

From 56f2eb15245efe07098ad46109d332d3b3af0085 Mon Sep 17 00:00:00 2001
From: Robin Salkeld <salkeldr@amazon.com>
Date: Wed, 15 Feb 2023 15:35:11 -0800
Subject: [PATCH 18/18] PR feedback

---
 dist/index.js              | 31 ++++++++++--------
 index.js                   | 32 ++++++++++--------
 test/setup-dafny-action.js | 66 +++++++++++++++++++++++++++++++++++++-
 3 files changed, 102 insertions(+), 27 deletions(-)

diff --git a/dist/index.js b/dist/index.js
index 7c48e21..ad4eb7f 100644
--- a/dist/index.js
+++ b/dist/index.js
@@ -6730,6 +6730,7 @@ async function installDotnetTool(toolName, version) {
 // Export functions for testing
 exports.dafnyURL = dafnyURL;
 exports.getDistribution = getDistribution;
+exports.latestNightlyVersionFromDotnetToolSearch = latestNightlyVersionFromDotnetToolSearch;
 
 async function dafnyURL(version, distribution) {
   const versionPath = version.startsWith("nightly") ? "nightly" : `v${version}`;
@@ -6743,14 +6744,6 @@ async function dafnyURL(version, distribution) {
 }
 
 async function latestNightlyVersion() {
-  // Shamelessly copied and modified from dafny-lang/ide-vscode.
-  // Parsing the dotnet tool output is obviously not great,
-  // and we could consider using the NuGet API in the future.
-  // Alternatively if we move to installing Dafny using `dotnet tool install`
-  // we could use the `--prerelease` flag, although that assumes
-  // that all nightly builds use a fresh version number,
-  // and can't be used together with `--version` to express something like
-  // "install the latest 3.X version including prereleases".
   const { exitCode, stdout, stderr } = await exec.getExecOutput(
     "dotnet",
     ["tool", "search", "Dafny", "--detail", "--prerelease"],
@@ -6761,7 +6754,19 @@ async function latestNightlyVersion() {
       `dotnet tool command failed (exitCode ${exitCode}):\n${stderr}"`
     );
   }
-  const entries = stdout
+  return latestNightlyVersionFromDotnetToolSearch(stdout)
+}
+
+function latestNightlyVersionFromDotnetToolSearch(output) {
+  // Shamelessly copied and modified from dafny-lang/ide-vscode.
+  // Parsing the dotnet tool output is obviously not great,
+  // and we could consider using the NuGet API in the future.
+  // Alternatively if we move to installing Dafny using `dotnet tool install`
+  // we could use the `--prerelease` flag, although that assumes
+  // that all nightly builds use a fresh version number,
+  // and can't be used together with `--version` to express something like
+  // "install the latest 3.X version including prereleases".
+  const entries = output
     .split("----------------")
     .map((entry) => entry.split(/\r?\n/).filter((e) => e !== ""));
   const dafnyEntry = entries.filter((entry) => entry[0] === "dafny")[0];
@@ -6771,12 +6776,12 @@ async function latestNightlyVersion() {
     .map((versionLine) => versionLine.trimStart().split(" ")[0]);
 
   const nightlies = versions.filter((l) => l.includes("nightly"));
-  const dates = nightlies.map((n, index) => {
-    const split = n.split("-");
-    return { index, date: split[2] + split[3] + split[4] };
+  const dates = nightlies.map(nightly => {
+    const date = new Date(nightly.split('-').slice(2, 5).join('-'))
+    return { nightly, date };
   });
   dates.sort((a, b) => (a.date < b.date ? 1 : -1));
-  const toolVersion = nightlies[dates[0].index];
+  const toolVersion = dates[0].nightly;
 
   // Slice off the "3.11.0.50201-" from 3.11.0.50201-nightly-2023-02-13-14bc57f, for e.g.
   const version = toolVersion.slice(toolVersion.indexOf("-") + 1);
diff --git a/index.js b/index.js
index 303a7b6..a7a9c27 100644
--- a/index.js
+++ b/index.js
@@ -42,6 +42,8 @@ async function installDotnetTool(toolName, version) {
 // Export functions for testing
 exports.dafnyURL = dafnyURL;
 exports.getDistribution = getDistribution;
+exports.latestNightlyVersionFromDotnetToolSearch =
+  latestNightlyVersionFromDotnetToolSearch;
 
 async function dafnyURL(version, distribution) {
   const versionPath = version.startsWith("nightly") ? "nightly" : `v${version}`;
@@ -55,14 +57,6 @@ async function dafnyURL(version, distribution) {
 }
 
 async function latestNightlyVersion() {
-  // Shamelessly copied and modified from dafny-lang/ide-vscode.
-  // Parsing the dotnet tool output is obviously not great,
-  // and we could consider using the NuGet API in the future.
-  // Alternatively if we move to installing Dafny using `dotnet tool install`
-  // we could use the `--prerelease` flag, although that assumes
-  // that all nightly builds use a fresh version number,
-  // and can't be used together with `--version` to express something like
-  // "install the latest 3.X version including prereleases".
   const { exitCode, stdout, stderr } = await exec.getExecOutput(
     "dotnet",
     ["tool", "search", "Dafny", "--detail", "--prerelease"],
@@ -73,7 +67,19 @@ async function latestNightlyVersion() {
       `dotnet tool command failed (exitCode ${exitCode}):\n${stderr}"`
     );
   }
-  const entries = stdout
+  return latestNightlyVersionFromDotnetToolSearch(stdout);
+}
+
+function latestNightlyVersionFromDotnetToolSearch(output) {
+  // Shamelessly copied and modified from dafny-lang/ide-vscode.
+  // Parsing the dotnet tool output is obviously not great,
+  // and we could consider using the NuGet API in the future.
+  // Alternatively if we move to installing Dafny using `dotnet tool install`
+  // we could use the `--prerelease` flag, although that assumes
+  // that all nightly builds use a fresh version number,
+  // and can't be used together with `--version` to express something like
+  // "install the latest 3.X version including prereleases".
+  const entries = output
     .split("----------------")
     .map((entry) => entry.split(/\r?\n/).filter((e) => e !== ""));
   const dafnyEntry = entries.filter((entry) => entry[0] === "dafny")[0];
@@ -83,12 +89,12 @@ async function latestNightlyVersion() {
     .map((versionLine) => versionLine.trimStart().split(" ")[0]);
 
   const nightlies = versions.filter((l) => l.includes("nightly"));
-  const dates = nightlies.map((n, index) => {
-    const split = n.split("-");
-    return { index, date: split[2] + split[3] + split[4] };
+  const dates = nightlies.map((nightly) => {
+    const date = new Date(nightly.split("-").slice(2, 5).join("-"));
+    return { nightly, date };
   });
   dates.sort((a, b) => (a.date < b.date ? 1 : -1));
-  const toolVersion = nightlies[dates[0].index];
+  const toolVersion = dates[0].nightly;
 
   // Slice off the "3.11.0.50201-" from 3.11.0.50201-nightly-2023-02-13-14bc57f, for e.g.
   const version = toolVersion.slice(toolVersion.indexOf("-") + 1);
diff --git a/test/setup-dafny-action.js b/test/setup-dafny-action.js
index da61dd0..e713031 100644
--- a/test/setup-dafny-action.js
+++ b/test/setup-dafny-action.js
@@ -1,4 +1,8 @@
-const { dafnyURL, getDistribution } = require("../index");
+const {
+  dafnyURL,
+  getDistribution,
+  latestNightlyVersionFromDotnetToolSearch,
+} = require("../index");
 const { expect } = require("chai");
 
 describe("dafnyURL", () => {
@@ -16,6 +20,13 @@ describe("dafnyURL", () => {
     );
   });
 
+  it("latest nightly parsing logic", async () => {
+    const test = latestNightlyVersionFromDotnetToolSearch(
+      sampleDotnetToolSearchOutput
+    );
+    expect(test).to.equal("nightly-2023-02-15-567a5ba");
+  });
+
   it("latest nightly usage", async () => {
     const test = await dafnyURL("nightly-latest", "ubuntu-16.04");
     expect(test).to.match(
@@ -34,6 +45,59 @@ describe("dafnyURL", () => {
   });
 });
 
+const sampleDotnetToolSearchOutput = `
+----------------
+dafny
+Latest Version: 3.11.0.50201
+Authors: Dafny
+Tags: 
+Downloads: 16159
+Verified: False
+Description: Package Description
+Versions: 
+	3.10.0.41215-nightly-2023-01-24-fda11e6 Downloads: 54
+	3.10.0.41215-nightly-2023-01-25-07932fc Downloads: 54
+	3.10.0.41215-nightly-2023-01-26-97f1ced Downloads: 47
+	3.10.0.41215-nightly-2023-01-27-5bd9203 Downloads: 50
+	3.10.0.41215-nightly-2023-01-28-acb7991 Downloads: 52
+	3.10.0.41215-nightly-2023-01-29-acb7991 Downloads: 51
+	3.10.0.41215-nightly-2023-01-30-acb7991 Downloads: 53
+	3.10.0.41215-nightly-2023-01-31-c23b224 Downloads: 57
+	3.10.0.41215-nightly-2023-02-01-c5b4e15 Downloads: 46
+	3.10.0.41215 Downloads: 166
+	3.11.0.50201-nightly-2023-02-01-0cff53e Downloads: 43
+	3.11.0.50201-nightly-2023-02-02-4e54d04 Downloads: 49
+	3.11.0.50201-nightly-2023-02-03-9b97489 Downloads: 41
+	3.11.0.50201-nightly-2023-02-04-b8d8816 Downloads: 34
+	3.11.0.50201-nightly-2023-02-05-b8d8816 Downloads: 33
+	3.11.0.50201-nightly-2023-02-06-b8d8816 Downloads: 34
+	3.11.0.50201-nightly-2023-02-07-2461f1f Downloads: 30
+	3.11.0.50201-nightly-2023-02-08-37cfcb0 Downloads: 31
+	3.11.0.50201-nightly-2023-02-09-a86c579 Downloads: 31
+	3.11.0.50201-nightly-2023-02-10-a2a4e1b Downloads: 27
+	3.11.0.50201-nightly-2023-02-10-a86c579 Downloads: 26
+	3.11.0.50201-nightly-2023-02-11-6aeaa2b Downloads: 28
+	3.11.0.50201-nightly-2023-02-11-a2a4e1b Downloads: 30
+	3.11.0.50201-nightly-2023-02-12-6aeaa2b Downloads: 29
+	3.11.0.50201-nightly-2023-02-13-14bc57f Downloads: 27
+	3.11.0.50201-nightly-2023-02-14-7cf7164 Downloads: 27
+	3.11.0.50201-nightly-2023-02-15-567a5ba Downloads: 14
+	3.11.0.50201 Downloads: 94
+
+----------------
+dafny-reportgenerator
+Latest Version: 1.2.0
+Authors: dafny-reportgenerator
+Tags: 
+Downloads: 11564
+Verified: False
+Description: Package Description
+Versions: 
+	1.0.0 Downloads: 248
+	1.0.1 Downloads: 525
+	1.2.0 Downloads: 10791
+`;
+
 describe("getDistribution", () => {
   // https://nodejs.org/docs/latest/api/os.html#os_os_platform
   [