Refactor config

Mainly an attempt to clear up what is configurable via git and what gets
loaded separately.

src/context.ts

@@ -1,34 +1,43 @@
 import * as shikiji from 'shikiji';
-import { Config } from './config';
+import { Config } from './getConfig';
 import { FormattedString, T } from './formattedString';
+import { ChalkInstance } from 'chalk';
 
 /**
  * Internal context object used to pass around config and config-derived
  * constants.
  */
 export type Context = Config & {
+    CHALK: ChalkInstance;
     SPLIT_DIFFS: boolean;
+    SCREEN_WIDTH: number;
     LINE_WIDTH: number;
     BLANK_LINE: string;
     HORIZONTAL_SEPARATOR: FormattedString;
     HIGHLIGHTER?: shikiji.Highlighter;
 };
 
-export async function getContextForConfig(config: Config): Promise<Context> {
+export async function getContextForConfig(
+    config: Config,
+    chalk: ChalkInstance,
+    screenWidth: number
+): Promise<Context> {
+    const SCREEN_WIDTH = screenWidth;
+
     // Only split diffs if there's enough room
-    const SPLIT_DIFFS = config.SCREEN_WIDTH >= config.MIN_LINE_WIDTH * 2;
+    const SPLIT_DIFFS = SCREEN_WIDTH >= config.MIN_LINE_WIDTH * 2;
 
     let LINE_WIDTH: number;
     if (SPLIT_DIFFS) {
-        LINE_WIDTH = Math.floor(config.SCREEN_WIDTH / 2);
+        LINE_WIDTH = Math.floor(SCREEN_WIDTH / 2);
     } else {
-        LINE_WIDTH = config.SCREEN_WIDTH;
+        LINE_WIDTH = SCREEN_WIDTH;
     }
 
     const BLANK_LINE = ''.padStart(LINE_WIDTH);
     const HORIZONTAL_SEPARATOR = T()
-        .fillWidth(config.SCREEN_WIDTH, '─')
-        .addSpan(0, config.SCREEN_WIDTH, config.BORDER_COLOR);
+        .fillWidth(SCREEN_WIDTH, '─')
+        .addSpan(0, SCREEN_WIDTH, config.BORDER_COLOR);
 
     let HIGHLIGHTER = undefined;
     if (config.SYNTAX_HIGHLIGHTING_THEME) {
@@ -39,6 +48,8 @@ export async function getContextForConfig(config: Config): Promise<Context> {
     }
     return {
         ...config,
+        CHALK: chalk,
+        SCREEN_WIDTH,
         SPLIT_DIFFS,
         LINE_WIDTH,
         BLANK_LINE,

src/getConfig.ts

@@ -0,0 +1,29 @@
+import { GitConfig } from './getGitConfig';
+import { Theme, loadTheme } from './themes';
+import * as shikiji from 'shikiji';
+
+export type Config = Theme & {
+    MIN_LINE_WIDTH: number;
+    WRAP_LINES: boolean;
+    HIGHLIGHT_LINE_CHANGES: boolean;
+};
+
+export const DEFAULT_THEME_NAME = 'dark';
+
+export const CONFIG_DEFAULTS: Omit<Config, keyof Theme> = {
+    MIN_LINE_WIDTH: 80,
+    WRAP_LINES: true,
+    HIGHLIGHT_LINE_CHANGES: true,
+};
+
+export function getConfig(gitConfig: GitConfig): Config {
+    const theme = loadTheme(gitConfig.THEME_NAME ?? DEFAULT_THEME_NAME);
+
+    return {
+        ...CONFIG_DEFAULTS,
+        ...theme,
+        ...gitConfig,
+        SYNTAX_HIGHLIGHTING_THEME: (theme.SYNTAX_HIGHLIGHTING_THEME ??
+            gitConfig.SYNTAX_HIGHLIGHTING_THEME) as shikiji.BundledTheme,
+    };
+}

src/getGitConfig.test.ts

@@ -0,0 +1,66 @@
+import { DEFAULT_THEME_NAME } from './getConfig';
+import {
+    DEFAULT_MIN_LINE_WIDTH,
+    GitConfig,
+    getGitConfig,
+} from './getGitConfig';
+
+const DEFAULT_CONFIG: GitConfig = {
+    WRAP_LINES: true,
+    HIGHLIGHT_LINE_CHANGES: true,
+    MIN_LINE_WIDTH: DEFAULT_MIN_LINE_WIDTH,
+    THEME_NAME: DEFAULT_THEME_NAME,
+};
+
+describe('getGitConfig', () => {
+    test('empty', () => {
+        expect(getGitConfig('')).toEqual(DEFAULT_CONFIG);
+    });
+
+    test('full', () => {
+        expect(
+            getGitConfig(`
+split-diffs.wrap-lines=false
+split-diffs.highlight-line-changes=false
+split-diffs.min-line-width=40
+split-diffs.theme-name=arctic
+split-diffs.syntax-highlighting-theme=dark-plus
+            `)
+        ).toEqual({
+            WRAP_LINES: false,
+            HIGHLIGHT_LINE_CHANGES: false,
+            MIN_LINE_WIDTH: 40,
+            THEME_NAME: 'arctic',
+            SYNTAX_HIGHLIGHTING_THEME: 'dark-plus',
+        });
+    });
+
+    test('partial', () => {
+        expect(
+            getGitConfig(`
+split-diffs.wrap-lines=true
+split-diffs.syntax-highlighting-theme=nord
+            `)
+        ).toEqual({
+            ...DEFAULT_CONFIG,
+            WRAP_LINES: true,
+            SYNTAX_HIGHLIGHTING_THEME: 'nord',
+        });
+    });
+
+    test('invalid values', () => {
+        expect(
+            getGitConfig(`
+split-diffs.wrap-lines=1
+split-diffs.highlight-line-changes=1
+split-diffs.min-line-width=bar
+split-diffs.syntax-highlighting-theme=foo
+split-diffs.theme-name=baz
+            `)
+        ).toEqual({
+            ...DEFAULT_CONFIG,
+            SYNTAX_HIGHLIGHTING_THEME: 'foo',
+            THEME_NAME: 'baz',
+        });
+    });
+});

src/getGitConfig.ts

@@ -1,21 +1,22 @@
-import { ChalkInstance } from 'chalk';
-import { exec } from 'child_process';
-import * as util from 'util';
-import { Config } from './config';
-import { loadTheme } from './themes';
-import * as shikiji from 'shikiji';
-const execAsync = util.promisify(exec);
+export type GitConfig = {
+    MIN_LINE_WIDTH: number;
+    WRAP_LINES: boolean;
+    HIGHLIGHT_LINE_CHANGES: boolean;
+    THEME_NAME: string;
+    SYNTAX_HIGHLIGHTING_THEME?: string;
+};
+
+export const DEFAULT_MIN_LINE_WIDTH = 80;
+export const DEFAULT_THEME_NAME = 'dark';
 
 const GIT_CONFIG_KEY_PREFIX = 'split-diffs';
 const GIT_CONFIG_LINE_REGEX = new RegExp(
     `${GIT_CONFIG_KEY_PREFIX}\.([^=]+)=(.*)`
 );
 
-async function getRawGitConfig() {
-    const { stdout } = await execAsync('git config -l');
-
+function extractFromGitConfigString(configString: string) {
     const rawConfig: Record<string, string> = {};
-    for (const line of stdout.trim().split('\n')) {
+    for (const line of configString.trim().split('\n')) {
         const match = line.match(GIT_CONFIG_LINE_REGEX);
         if (!match) {
             continue;
@@ -26,30 +27,10 @@ async function getRawGitConfig() {
     return rawConfig;
 }
 
-// TODO: Make this less manual
-export async function getGitConfig(
-    screenWidth: number,
-    chalk: ChalkInstance
-): Promise<Config> {
-    const rawConfig = await getRawGitConfig();
-
-    // Defaults to "dark"
-    const themeName = rawConfig['theme-name'] ?? 'dark';
-    const theme = loadTheme(themeName);
-
-    // Defaults to the theme's setting
-    const syntaxHighlightingTheme = (rawConfig['syntax-highlighting-theme'] ??
-        theme.SYNTAX_HIGHLIGHTING_THEME) as shikiji.BundledTheme;
-
-    // Defaults to true
-    const wrapLines = rawConfig['wrap-lines'] === 'false' ? false : true;
-
-    // Defaults to true
-    const highlightLineChanges =
-        rawConfig['highlight-line-changes'] === 'false' ? false : true;
+export function getGitConfig(configString: string): GitConfig {
+    const rawConfig = extractFromGitConfigString(configString);
 
-    // Defaults to 80
-    let minLineWidth = 80;
+    let minLineWidth = DEFAULT_MIN_LINE_WIDTH;
     try {
         const parsedMinLineWidth = parseInt(rawConfig['min-line-width'], 10);
         if (!isNaN(parsedMinLineWidth)) {
@@ -58,12 +39,10 @@ export async function getGitConfig(
     } catch {}
 
     return {
-        ...theme,
-        CHALK: chalk,
-        SCREEN_WIDTH: screenWidth,
         MIN_LINE_WIDTH: minLineWidth,
-        WRAP_LINES: wrapLines,
-        HIGHLIGHT_LINE_CHANGES: highlightLineChanges,
-        SYNTAX_HIGHLIGHTING_THEME: syntaxHighlightingTheme,
+        WRAP_LINES: rawConfig['wrap-lines'] !== 'false',
+        HIGHLIGHT_LINE_CHANGES: rawConfig['highlight-line-changes'] !== 'false',
+        THEME_NAME: rawConfig['theme-name'] ?? DEFAULT_THEME_NAME,
+        SYNTAX_HIGHLIGHTING_THEME: rawConfig['syntax-highlighting-theme'],
     };
 }

src/index.test.ts

@@ -1,74 +1,95 @@
 import { Readable, Writable } from 'stream';
-import { Config } from './config';
+import { Config } from './getConfig';
 import { getContextForConfig } from './context';
-import { ThemeColorName } from './themes';
+import { Theme, ThemeColorName } from './themes';
 import { transformContentsStreaming } from './transformContentsStreaming';
+import { ChalkInstance } from 'chalk';
 
 const TEST_THEME = Object.fromEntries(
     Object.keys(ThemeColorName).map((name) => [name, {}])
-);
+) as Theme;
 
 const replaceColoredText = () => (text: string) => text.replace(/./g, '░');
 
+// Provide a fake chalk implementation to make it easier to read snapshots
+// @ts-expect-error
+const TEST_CHALK = {
+    rgb: replaceColoredText,
+    bgRgb: replaceColoredText,
+} as ChalkInstance;
+
 const TEST_CONFIG: Config = {
-    // Provide a fake chalk implementation to make it easier to read snapshots
-    CHALK: {
-        // @ts-expect-error
-        rgb: replaceColoredText,
-        // @ts-expect-error
-        bgRgb: replaceColoredText,
-    },
-    SCREEN_WIDTH: 120,
     MIN_LINE_WIDTH: 60,
     WRAP_LINES: false,
     HIGHLIGHT_LINE_CHANGES: false,
     ...TEST_THEME,
 };
 
-const CONFIG_OVERRIDES: Record<string, Partial<Config>> = {
+type TestOverrides = { screenWidth: number; config: Partial<Config> };
+
+const CONFIG_OVERRIDES: Record<string, TestOverrides> = {
     splitWithoutWrapping: {
-        SCREEN_WIDTH: 80,
-        MIN_LINE_WIDTH: 40,
-        WRAP_LINES: false,
+        screenWidth: 80,
+        config: {
+            MIN_LINE_WIDTH: 40,
+            WRAP_LINES: false,
+        },
     },
     splitWithWrapping: {
-        SCREEN_WIDTH: 80,
-        MIN_LINE_WIDTH: 40,
-        WRAP_LINES: true,
+        screenWidth: 80,
+        config: {
+            MIN_LINE_WIDTH: 40,
+            WRAP_LINES: true,
+        },
     },
     unifiedWithWrapping: {
-        SCREEN_WIDTH: 80,
-        MIN_LINE_WIDTH: 80,
-        WRAP_LINES: true,
+        screenWidth: 80,
+        config: {
+            MIN_LINE_WIDTH: 80,
+            WRAP_LINES: true,
+        },
     },
     // This is in split mode
     inlineChangesHighlighted: {
-        HIGHLIGHT_LINE_CHANGES: true,
-        DELETED_WORD_COLOR: { color: { r: 255, g: 0, b: 0, a: 255 } },
-        INSERTED_WORD_COLOR: { color: { r: 0, g: 255, b: 0, a: 255 } },
+        screenWidth: 120,
+        config: {
+            HIGHLIGHT_LINE_CHANGES: true,
+            DELETED_WORD_COLOR: { color: { r: 255, g: 0, b: 0, a: 255 } },
+            INSERTED_WORD_COLOR: { color: { r: 0, g: 255, b: 0, a: 255 } },
+        },
     },
     unifiedWithInlineChangesHighlighted: {
-        SCREEN_WIDTH: 80,
-        MIN_LINE_WIDTH: 80,
-        HIGHLIGHT_LINE_CHANGES: true,
-        DELETED_WORD_COLOR: { color: { r: 255, g: 0, b: 0, a: 255 } },
-        INSERTED_WORD_COLOR: { color: { r: 0, g: 255, b: 0, a: 255 } },
+        screenWidth: 80,
+        config: {
+            MIN_LINE_WIDTH: 80,
+            HIGHLIGHT_LINE_CHANGES: true,
+            DELETED_WORD_COLOR: { color: { r: 255, g: 0, b: 0, a: 255 } },
+            INSERTED_WORD_COLOR: { color: { r: 0, g: 255, b: 0, a: 255 } },
+        },
     },
     syntaxHighlighted: {
-        SCREEN_WIDTH: 80,
-        MIN_LINE_WIDTH: 40,
-        WRAP_LINES: false,
-        SYNTAX_HIGHLIGHTING_THEME: 'dark-plus',
+        screenWidth: 80,
+        config: {
+            MIN_LINE_WIDTH: 40,
+            WRAP_LINES: false,
+            SYNTAX_HIGHLIGHTING_THEME: 'dark-plus',
+        },
     },
 };
 
-for (const [configName, configOverride] of Object.entries(CONFIG_OVERRIDES)) {
+for (const [configName, { screenWidth, config }] of Object.entries(
+    CONFIG_OVERRIDES
+)) {
     async function transform(input: string): Promise<string> {
         const testConfig: Config = {
             ...TEST_CONFIG,
-            ...configOverride,
+            ...config,
         };
-        const context = await getContextForConfig(testConfig);
+        const context = await getContextForConfig(
+            testConfig,
+            TEST_CHALK,
+            screenWidth
+        );
 
         let string = '';
         await transformContentsStreaming(